Refrigerant Circuit Pressures Specified Values, Vehicles With Heat Pump

WARNING: This page does not describe the selected car, but rather 23 other vehicles, including the 2017 Audi S5, 2017 Audi A5 Quattro, 2016 Audi S5, 2016 Audi A5 Quattro, and 2015 Audi S5. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

On vehicles with a high-voltage system and heat pump installed in the refrigerant circuit and electrically activated vehicles which regulate the flow of the refrigerant in the refrigerant circuit depending on the current operating condition. There are different versions of these valves. Refer to

and use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

On vehicles with the "heat pump" function and/or "high-voltage battery cooling" in not all operating conditions is the A/C system high pressure on the service connection of the high pressure side. Depending on the A/C system operating condition, the refrigerant circuit pressure on the high pressure side can only be measured via the pressure/temperature sensor installed in the refrigerant circuit on these vehicles. Refer to

and use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

On these vehicles the refrigerant circuit of the A/C system is used not only to cool the vehicle interior but also to cool the hybrid battery unit (via the refrigerant circuit for the high-voltage system) and to heat the vehicle interior (at low ambient temperature) via the heat pump function. So in order for these functions to be performed, the various valves, pressure and temperature sensors as well as the pumps in the refrigerant circuit and in the high-voltage system coolant circuit must be installed correctly and function correctly. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to

and COOLING SYSTEM/COOLANT - CAUA , or COOLING SYSTEM/COOLANT - CFSA , or COOLANT SYSTEM/COOLANT - CAED, CAEB, CPMB, CPMA , or COOLANT SYSTEM/COOLANT - CALA , or COOLANT SYSTEM/COOLANT - CABB, CABA, CABD, CAEA, CAEB, CDHB, CDNB, CDNC, CDHA, CDZA, CADA, CCUA, CFKA, CPMA, CAED, CPMB, CHJA, CPEA .

To determine the possible cause of a malfunction, different routines are stored in the basic setting of the thermal management control module, which activate these functions: "Cooling the A/C system", "heat pump", and "Cooling the components of the high-voltage system". Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

High-Pressure Side:

Increasing from initial pressure (when connecting the pressure gauges) to a maximum of 20 bar (290 psi).

NOTE:

Depending on the layout of the high pressure side service connection and the operating condition, the high pressure can only be measured via the pressure/temperature sensor installed in the refrigerant circuit. Refer to

Low-Pressure Side:

Decreasing from initial pressure (when connecting the pressure gauges) to a value between 1.5 and 2.3 bar (21.76 to 33.36 psi) absolute pressure (depending on the required cooling output).

A/C Compressor Speed:

Depending on the required cooling output between 800 and 8500/min (currently a maximum of 5000/min for parked vehicles).

NOTE:

The temperature of the air downstream of the evaporator, the current A/C compressor speed and the pressure of the refrigerant on the high pressure side are displayed as the measured value by various control modules (for example, by the thermal management control module, the front A/C display control head or the Climatronic Control Module -J255-), depending on the vehicle. Refer to OVERVIEW - A/C SYSTEM and use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

If a high cooling output is required (for example, a high outside temperature and the blower speed set on high), then the A/C compressor will not bring the pressure on the low pressure side to the required value (for example, for a certain time after turning on the A/C). The A/C compressor is not actuated at the maximum specified speed (of approximately 8500/min) on a stationary or slow moving vehicle (up to a speed of approximately 45 km/h (28 mph)) (the A/C compressor speed is limited to approximately 5000/min). After a vehicle reaches a speed of more than approximately 45 km/h (28 mph), the limit for the maximum permissible A/C compressor speed is lifted. At a A/C compressor speed of 5000/min, a high outside temperature and a high fresh air blower speed (inefficient environmental controls), the A/C compressor output (the delivery volume) is no longer sufficient to reduce the pressure on the low pressure side to the target value. To check the A/C compressor control under these conditions, for example, the fresh air blower is activated only with approximately 40% of the maximum voltage, check the pressures at a lower fresh air blower speed. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function (for A/C system and the battery regulation). Refer to COOLING OUTPUT, CHECKING .

Under unfavorable conditions (very high ambient temperatures, high humidity), pressure on high-pressure side may increase to max. 29 bar (421 psi).

The specified speed of the A/C compressor is displayed and the measured value for example from the thermal management control module using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

The refrigerant circuit pressure (low or high pressure) measured by the different pressure/temperature sensors depending on the respective operating condition is displayed as the measured value by the respective control module. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to

The low pressure settles depending on the A/C compressor speed and the control characteristic of the expansion valve (on the evaporator of the front heater and A/C unit) within the compressor output range in tolerance range (1.5 to 2.3 bar (21.76 to 33.36 psi) positive pressure).

The target speed for the A/C compressor must be greater than 1500/min for this test.

In setting "maximum cooling output" the target speed is regulated to approximately 4000 up to 5000/min. This value is vehicle-specific and is displayed and the measured value of the respective control module using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

At absolute pressure, 0 bar (0 psi) corresponds to absolute vacuum. Normal ambient pressure corresponds to 1 bar (14.5 psi) absolute pressure. 0 bar (0 psi) pressure corresponds to an absolute pressure of 1 bar (14.5 psi) on most pressure gauges (indicated by -1 bar (-14.5 psi) below 0).

If on a vehicle with two evaporators (one in the heater and A/C unit and one for cooling the heater and A/C unit for example the heat exchanger for the high-voltage battery) and two condensers (one in the front end for the A/C system and one as the heat exchanger for the heat pump function) depending on the selected function on a component the measured temperature or pressure, the specified value corresponds to another component whose specifications are not achieved, check the activation of the electrically activated valves installed in the refrigerant circuit. At the same time, also pay attention to the pressure distribution in the refrigerant circuit depending on the installed check valves. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to

For the correct A/C function it is also necessary that depending on the selected functions of the respective heater cores enough heat is supplied or removed. Therefore also pay attention to the incorporation of the heater core into the respective coolant circuit for the engine and high-voltage system and the function of the pumps and valves installed in it. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to COOLANT CIRCUIT .

Since the evaporator for cooling the high-voltage components output (in the battery cooling module and in the high-voltage battery heat exchanger) is smaller than the evaporator output in the heater and A/C unit, the required target temperature may still be reached in the evaporator for cooling the high-voltage battery with too little refrigerant in the refrigerant circuit, but the target temperature in the heater and A/C unit evaporator will no longer be attainable (even though the A/C compressor is activated with increased A/C unit speed).

Possible Deviation from Specified Value, the Cause and Its Elimination
High pressure remains constant or increases only slightly (above pressure with engine stopped), Low pressure quickly drops to target value or lower. The required cooling output is not attained in the heater and A/C unit evaporator and in the evaporator for cooling the high-voltage components.		Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON
High pressure normal Low pressure corresponds with the target value, The requested cooling output is not attained.		Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON
High pressure normal Low pressure normal or too low (less than the specified value) The required cooling output is only not attained at the heater and A/C unit evaporator (the cooling output on the evaporator for cooling the high-voltage components is OK).		Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON
High pressure normal Low pressure normal or too low (less than the specified value) The required cooling output is only not attained at the evaporator for cooling the high-voltage components (the cooling output at the front heater and A/C unit evaporator is OK).		Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON
High pressure does not increase or only increases slightly above pressure with engine stopped. Low pressure does not drop or drops only slightly. The required cooling output is not attained in the heater and A/C unit evaporator (and in the evaporator for cooling the high-voltage components).		Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON
High pressure increases above specification The low pressure quickly falls to the target value, The required cooling output is not attained in the front heater and A/C unit evaporator (and/or in the evaporator for cooling the high-voltage components).		Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON
High pressure and low pressure normal at first, after some time high pressure increases above the specified value and the low pressure falls to the specified value or lower. The required cooling output is not or no longer attained in the heater and A/C unit evaporator (and/or in the evaporator for cooling the high-voltage components).		Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON
High pressure and lower pressure normal first, after a long period of driving, the low pressure falls below the specified value (the evaporator in the heater and A/C unit iced up).		Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON
High pressure normal Low pressure too low, The required cooling output is not attained in the heater and A/C unit evaporator (and/or in the evaporator for cooling the high-voltage components).		Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON
High pressure normal or too high Low pressure too high. A/C compressor noise (particularly after switch-on) The required cooling output is not attained in the front heater and A/C unit evaporator and/or in the evaporator for cooling the high-voltage components.		Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON
High and low pressure normal The required cooling output is not attained in the heater and A/C unit evaporator (and in the evaporator for cooling the high-voltage components). or High and low pressure normal A/C compressor noise (particularly after switch-on) The required cooling output is not attained in the heater and A/C unit evaporator (and/or in the evaporator for cooling the high-voltage components).		Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON
High and low pressure normal The required cooling output is attained in the front heater and A/C unit evaporator (and on the evaporator for cooling the high-voltage components). The required cooling output is not attained on the heater core for the heat pump output.		Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON

Possible Deviation from Specified Value During the Pressure Test
High pressure remains constant or increases only slightly (above pressure with engine stopped), Low pressure quickly drops to target value or lower. The required cooling output is not attained in the heater and A/C unit evaporator and in the evaporator for cooling the high-voltage components.
Possible causes for the deviation from specified value and their solutions
One in or on the removed refrigerant circuit pressure/temperature sensor or temperature sensor sends incorrect values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM . Not enough refrigerant in refrigerant circuit Activation of the A/C compressor or a valve installed in the refrigerant circuit is faulty. -- Check the measured values of the different pressure/temperature sensor and temperature sensor when operating the A/C system, and replace the components with incorrect measured values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM . If no errors can be detected, evacuate the refrigerant.-- Extract refrigerant from the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, DISCHARGING .-- If the extracted refrigerant quantity is significantly less than the specified capacity (more that 100g (3.5 oz) less). Refer to TECHNICAL DATA , and look for leaks and correct. Refer to LEAKS, FINDING .-- The extracted refrigerant quantity corresponds approximately to the specified capacity, check the activation of the A/C compressor and the installed shut-off valve, if not malfunction is determined, replace the expansion valve for the evaporator in the heater and A/C unit. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table . -- Depending on the results, service the activation or replace the faulty component (A/C compressor, shut-off valve, expansion valve). Refer to the Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .
Final Procedures
-- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .

NOTE:

To determine the possible cause of a malfunction, different routines are stored in the basic setting of the control module (for example in the thermal management control module) which activate these functions: "cooling the A/C system", "heat pump", and "cooling the components of the high-voltage system". Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to

If for this concern no malfunction can be determined, check the activation of the electrically activated valves installed in the refrigerant circuit next. If no error can be detected here, remove and check the check valves installed in the refrigerant circuit, if no error can be detected here clean the refrigerant circuit (flush with refrigerant R1234yf). One of these malfunctions may arise due to a constriction or a blockage in the refrigerant circuit. Refer to

and REFRIGERANT CIRCUIT, CLEANING .

and use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

Before beginning the repair work check the measured values of the different pressure/temperature sensors installed in the refrigerant circuit. If there is an error in the measured value of a pressure/temperature sensor, this can lead to problems in the cooling output, or the evaporator in the front heater and A/C unit can ice over. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to

, and appropriate SYSTEM WIRING DIAGRAMS information.

When checking the different functions (heat pump or cooling the high-voltage battery), also pay attention to the activation and function of the coolant circuit components that are involved with these functions. Refer to COOLANT CIRCUIT .

If the A/C system function is not OK after repeating the test, for example after replacing expansion valve (reinstalling the old expansion valve), clean the refrigerant circuit by flushing using the refrigerant R134a. Refer to REFRIGERANT CIRCUIT, CLEANING . Then replace the A/C compressor and receiver/dryer or dryer cartridge.

With a malfunction on one of the temperature sensors, the evaporator may ice up even though the quantity of refrigerant in the circuit is OK.

If the expansion valve on the evaporator in the A/C unit is faulty (constantly closed or does not open far enough), the A/C compressor is activated to maximum output and the low pressure drops to the value in the graph or below (A/C compressor draws off the refrigerant from the low pressure side). Since the refrigerant cannot flow via the expansion valve, the cooling output is not attained, high pressure may also not increase or only increase slightly due to the absence of energy. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to COOLING OUTPUT, CHECKING .

The evaporator in the heater and A/C unit has a larger output than the evaporator for cooling the high-voltage battery. Depending on the version to cool the electric vehicle battery/hybrid battery unit (hybrid battery), the expansion valve in front of this evaporator (the heat exchanger for cooling the high-voltage system components) is currently activated only from or up to a certain battery temperature by the respective control module, so that the exchange of energy via this evaporator does not increase, or only slightly. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to COOLING OUTPUT, CHECKING .

If there is too much refrigerant oil in the circuit, the compressor must be drained (flushed) and the receiver/dryer/dryer cartridge must be replaced. After cleaning the refrigerant circuit (flushing with refrigerant R134a) and fill it with the correct quantity of refrigerant oil in the circuit (in the A/C compressor). Refer to REFRIGERANT CIRCUIT, CLEANING and TECHNICAL DATA .

Possible Deviation from Specified Value during the Pressure Test
High pressure normal Low pressure corresponds with the target value, The requested cooling output is not attained.
Possible causes for the deviation from specified value and their solutions
One in or on the removed refrigerant circuit pressure/temperature sensor or temperature sensor sends incorrect values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM . Not enough refrigerant in refrigerant circuit The shut-off valve in front of the expansion valve for the evaporator in the front heater and A/C unit is faulty. If one of the other valves installed in the refrigerant circuit is faulty or does not work correctly. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table . The expansion valve for the evaporator in the front heater and A/C unit is faulty. -- Check the measured values of the different pressure/temperature sensor and temperature sensor when operating the A/C system, and replace the components with incorrect measured values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM . If no errors can be detected, evacuate the refrigerant.-- Extract refrigerant from the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, DISCHARGING .-- If the extracted refrigerant quantity is significantly less than the specified capacity (more that 100g (3.5 oz) less). Refer to TECHNICAL DATA , and look for leaks and correct. Refer to LEAKS, FINDING .-- The extracted refrigerant quantity corresponds approximately to the specified capacity, check the activation of the A/C compressor and the installed shut-off valve if no malfunction is determined. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table -- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .-- Check the function and activation of the various valves installed in the refrigerant circuit via the pressure distribution in the refrigerant circuit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- Depending on the results, service the activation or replace the faulty component (shut-off valve/expansion valve). Refer to the Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .
Final Procedures
-- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .

NOTE:

Pay attention to the previous notes.

Possible Deviation from Specified Value during the Pressure Test
High pressure normal Low pressure normal or too low (less than the specified value) The required cooling output is only not attained at the heater and A/C unit evaporator (the cooling output on the evaporator for cooling the high-voltage components is OK).
Possible causes for the deviation from specified value and their solutions
One in or on the removed refrigerant circuit pressure/temperature sensor or temperature sensor sends incorrect values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM . Not enough refrigerant in refrigerant circuit Activation of the A/C compressor is faulty. The expansion valve for the evaporator in the front heater and A/C unit is faulty. The shut-off valve in front of the expansion valve for the evaporator in the front heater and A/C unit is faulty. One or the other valves installed in the refrigerant circuit is faulty or does not work correctly. -- Check the measured values of the different pressure/temperature sensor and temperature sensor when operating the A/C system, and replace the components with incorrect measured values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM . If no errors can be detected, evacuate the refrigerant.-- Extract refrigerant from the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, DISCHARGING .-- If the extracted refrigerant quantity is significantly less than the specified capacity (more that 100g (3.5 oz) less). Refer to TECHNICAL DATA , and look for leaks and correct. Refer to LEAKS, FINDING .-- The extracted refrigerant quantity corresponds approximately to the specified capacity, check the activation of the A/C compressor and the installed shut-off valve if no malfunction is determined. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table -- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .-- Check the function and activation of the various valves installed in the refrigerant circuit via the pressure distribution in the refrigerant circuit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- Depending on the results, service the activation or replace the faulty component (shut-off valve/expansion valve). Refer to the Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .
Final Procedures
-- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .

NOTE:

Pay attention to the previous notes.

Possible Deviation from Specified Value During the Pressure Test
High pressure normal Low pressure normal or too low (less than the specified value) The required cooling output is only not attained at the evaporator for cooling the high-voltage components (the cooling output at the front heater and A/C unit evaporator is OK).
Possible causes for the deviation from specified value and their solutions
If one of the valves installed in the refrigerant circuit is faulty or does not work correctly. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table . One of the pumps or one of the valves in the high-voltage system coolant circuit is faulty or does not function correctly. Refer to COOLANT CIRCUIT . One in or on the removed refrigerant circuit pressure/temperature sensor or temperature sensor sends incorrect values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM . Constriction of blockage in the refrigerant line to or from the expansion valve on the evaporator for cooling the high-voltage components. -- Check the measured values of the different pressure/temperature sensor and temperature sensor when operating the A/C system, and replace the components with incorrect measured values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM .-- Check the function and activation of the various valves installed in the refrigerant circuit via the pressure distribution in the refrigerant circuit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- Check the function and activation of the components for cooling the high-voltage components. Use Vehicle Diagnostic Tester in the "Guided Fault Finding" for the air conditioner, the A/C Compressor and the Battery Regulation.-- Depending on the result, service the activation or a faulty component (shut-off valve, expansion valve, coolant pump, coolant shut-off valve). Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table and Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- Check the refrigerant circuit lines, if they are kinked or constricted replace the hose or pipe of this component.-- If no malfunction can be determined clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING .
Final Procedures
-- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .

NOTE:

Pay attention to the previous notes.

Possible Deviation from Specified Value during the Pressure Test
High pressure does not increase or only increases slightly above pressure with engine stopped. Low pressure does not drop or drops only slightly. The required cooling output is not attained in the heater and A/C unit evaporator (and in the evaporator for cooling the high-voltage components).
Possible causes for the deviation from specified value and their solutions
No activation of the A/C compressor, the A/C compressor is not driven. If one of the valves installed in the refrigerant circuit is faulty or does not work correctly. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table . Constriction or obstruction in refrigerant circuit (for example, inside the refrigerant line between the service connection "low pressure side" and the A/C compressor). -- Check the activation and function of the A/C compressor and service using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.-- Check the function and activation of the various valves installed in the refrigerant circuit via the pressure distribution in the refrigerant circuit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- Depending on the results, service the activation or replace the faulty component (A/C compressor, shut-off valve, expansion valve). Refer to the Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- Check the refrigerant circuit lines. If the hose or pipe is kinked or constricted, remove this component. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- Run hand over refrigerant circuit to check for differences in temperature (position with a blockage). If there is a blockage clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING .-- If a malfunction is determined on the A/C compressor, replace the A/C compressor. Refer to COMPONENTS, REPLACING .-- If no malfunction can be determined clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING .
Final Procedures
-- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .

NOTE:

Pay attention to the previous notes.

Possible Deviation from Specified Value during the Pressure Test
High pressure increases above specification The low pressure quickly falls to the target value, The required cooling output is not attained in the front heater and A/C unit evaporator (and/or in the evaporator for cooling the high-voltage components).
Possible causes for the deviation from specified value and their solutions
A/C compressor activation or functionality malfunctioning. If one of the valves installed in the refrigerant circuit is faulty or does not work correctly. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table . Constriction or obstruction in refrigerant circuit Expansion valve malfunctioning -- Check the activation and function of the A/C compressor and service using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.-- Check the function and activation of the various valves installed in the refrigerant circuit via the pressure distribution in the refrigerant circuit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- Check the refrigerant circuit lines. If the hose or pipe is kinked or constricted, remove this component. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- Run hand over refrigerant circuit to check for differences in temperature (position with a blockage). If there is a blockage clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING .
Final Procedures
-- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .

NOTE:

With this malfunction, evaporator may ice up although the quantity of refrigerant in circuit is OK.

If the expansion valve in the heater and A/C unit evaporator or the installed shut-off valve is malfunctioning (permanently closed or does not open sufficiently), the A/C compressor is actuated to maximum output and the low pressure drops to specification or below (compressor draws off refrigerant from low-pressure side). Since no (or little) the refrigerant can flow via the expansion valve, the cooling output is not attained, high pressure may also not increase or only increase slightly due to the absence of energy. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to COOLING OUTPUT, CHECKING .

If the expansion valve for the evaporator for cooling the high-voltage components is faulty (or the function and activation is faulty) is always closed or does not open wide enough the A/C compressor is also activated with the maximum output (the required temperatures in the heat exchanger are not reached). The pressure on the low pressure side only then falls to the specified value or lower when at the same time the front heater and A/C unit no cooling output is needed. The A/C compressor extracts the refrigerant from the low pressure side from both evaporators. Because no refrigerant can low over the expansion valve in the front heater and A/C unit and the cooling output in the evaporator for cooling the high voltage battery is not reached (there is a malfunction in the area of the evaporator for the cooling of the high voltage battery) the electric A/C compressor is activated with a higher speed. If not refrigerant can flow the pressure on the low pressure side falls under the specified value, high pressure may also not increase or only increase slightly due to the absence of energy. The same applies if a valve in the refrigerant circuit is not OK a malfunction in the incorporation of the evaporator for cooling the high-voltage battery in the high-voltage system refrigerant circuit or the pump or a valve installed there is not OK. Then the High-Voltage Battery Heat Exchanger is cooled, but the cooled coolant reached the high-voltage battery heat exchanger which should not be cooled. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to COOLANT CIRCUIT .

Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON for additional information. To determine the possible cause of a malfunction, different routines are stored in the basic setting of the control module (for example in the thermal management control module) which activate these functions: "cooling the A/C system", "heat pump", and "cooling the components of the high-voltage system". Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

Possible Deviation from Specified Value during the Pressure Test
High pressure and low pressure normal at first, after some time high pressure increases above the specified value and the low pressure falls to the specified value or lower. The required cooling output is not or no longer attained in the heater and A/C unit evaporator (and/or in the evaporator for cooling the high-voltage components).
Possible causes for the deviation from specified value and their solutions
One in or on the removed refrigerant circuit pressure/temperature sensor or temperature sensor sends incorrect values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM . Activation of the A/C compressor is faulty. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. If one of the valves installed in the refrigerant circuit is faulty or does not work correctly. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table . Moisture in refrigerant circuit -- Check the measured values of the different pressure/temperature sensor and temperature sensor when operating the A/C system, and replace the components with incorrect measured values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM .-- Check the activation and function of the A/C compressor and service using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.-- Check the function and activation of the various valves installed in the refrigerant circuit via the pressure distribution in the refrigerant circuit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- If no malfunction can be determined clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING .
Final Procedures
-- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .

NOTE:

Pay attention to the previous notes.

Possible Deviation from Specified Value during the Pressure Test
High pressure and lower pressure normal first, after a long period of driving, the low pressure falls below the specified value (the evaporator in the heater and A/C unit iced up).
Possible causes for the deviation from specified value and their solutions
One in or on the removed refrigerant circuit pressure/temperature sensor or temperature sensor sends incorrect values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM . Activation of the A/C compressor is faulty. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. If one of the valves installed in the refrigerant circuit is faulty or does not work correctly. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table . One in or on the removed refrigerant circuit pressure/temperature sensor or temperature sensor sends incorrect values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM . Moisture in refrigerant circuit -- Check the measured values of the different pressure/temperature sensor and temperature sensor when operating the A/C system, and replace the components with incorrect measured values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM .-- Check the activation and function of the A/C compressor and service using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.-- Check the function and activation of the various valves installed in the refrigerant circuit via the pressure distribution in the refrigerant circuit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- If no malfunction can be determined, replace the desiccant bag/dryer cartridge (or reservoir/receiver/dryer) and evacuate the refrigerant circuit for at least three hours.
Final Procedures
-- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .

NOTE:

First, it is not necessary to clean the refrigerant circuit (flushing with refrigerant R1234yf) in case of this complaint because generally only a small amount of moisture is in the system and this can be removed by a long evacuation. Refer to REFRIGERANT CIRCUIT, CLEANING .

If a problem involving moisture in refrigerant circuit only occurs after a lengthy operating period or only infrequently (low pressure drops below specification and evaporator ices up), it is sufficient to replace the dryer installed in receiver/dryer (adjust quantity of refrigerant oil). Refrigerant circuit is then to be evacuated for at least three hours.

With this malfunction, evaporator may ice up although the quantity of refrigerant in circuit is OK.

A malfunction on the Evaporator Vent Temperature Sensor -G263- or/and on the pressure/temperature sensor the can lead to the refrigerant circuit freezing-up. For this concern also pay attention to the measured values of the different pressure/temperature sensor in the refrigerant circuit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to COOLING OUTPUT, CHECKING .

Possible Deviation from Specified Value During the Pressure Test
High pressure normal Low pressure too low, The required cooling output is not attained in the heater and A/C unit evaporator (and/or in the evaporator for cooling the high-voltage components).
Possible causes for the deviation from specified value and their solutions
Not enough refrigerant in refrigerant circuit If the activation or function of the A/C compressor faulty use the Vehicle Diagnostic Tester in "Guided Fault Finding" function. If one of the valves installed in the refrigerant circuit is faulty or does not work correctly. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table . One in or on the removed refrigerant circuit pressure/temperature sensor or temperature sensor sends incorrect values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM . -- Check the measured values of the different pressure/temperature sensor and temperature sensor when operating the A/C system, and replace the components with incorrect measured values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM . If no errors can be detected, evacuate the refrigerant.-- Extract refrigerant from the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, DISCHARGING .-- If the extracted refrigerant quantity is significantly less than the specified capacity (more that 100g (3.5 oz) less). Refer to TECHNICAL DATA , and look for leaks and correct. Refer to LEAKS, FINDING .-- The extracted refrigerant quantity corresponds approximately to the specified capacity, check the activation of the A/C compressor and the installed shut-off valve if no malfunction is determined. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table -- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .-- Check the activation and function of the A/C compressor and service using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.-- Check the function and activation of the various valves installed in the refrigerant circuit via the pressure distribution in the refrigerant circuit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- Depending on the results, service the activation or replace the faulty component (A/C compressor, shut-off valve, expansion valve, pressure/temperature sensor). Refer to the Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- If no malfunction can be determined clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING .
Final Procedures
-- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .

NOTE:

For the malfunction "high pressure normal, low pressure too low", note the following: With this fault, it may be that the evaporator in the heater and A/C unit is icing up although the refrigerant quantity in the circuit is OK.

If there is a fault in the A/C compressor (the A/C compressor is activated by the A/C compressor control module at too high of a speed), it is not necessary to clean the refrigerant circuit by flushing with refrigerant R1234yf. In this case, it is sufficient to replace the A/C compressor (observe quantity of refrigerant oil in A/C compressor and if necessary adjust). Refer to REFRIGERANT CIRCUIT, CLEANING .

A malfunction on the Evaporator Vent Temperature Sensor -G263- or/and on the pressure/temperature sensor the can lead to this concern. Also pay attention to the measured values of the different pressure/temperature sensor in the refrigerant circuit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to COOLING OUTPUT, CHECKING .

Possible Deviation from Specified Value during the Pressure Test
High pressure normal or too high Low pressure too high. A/C compressor noise (particularly after switch-on) The required cooling output is not attained in the front heater and A/C unit evaporator and/or in the evaporator for cooling the high-voltage components.
Possible causes for the deviation from specified value and their solutions
Activation of the A/C compressor is faulty. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. If one of the valves installed in the refrigerant circuit is faulty or does not work correctly. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table . One in or on the removed refrigerant circuit pressure/temperature sensor or temperature sensor sends incorrect values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM . Too much refrigerant in the circuit. Too much refrigerant oil in the circuit. -- Check the measured values of the different pressure/temperature sensor and temperature sensor when operating the A/C system, and replace the components with incorrect measured values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM .-- Check the activation and function of the A/C compressor and service using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.-- Check the function and activation of the various valves and pressure/temperature sensors installed in the refrigerant circuit via the pressure distribution in the refrigerant circuit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- If no malfunction can be determined, extract the refrigerant from the refrigerant circuit. If quantity of refrigerant extracted is substantially greater than specified capacity: -- Fill the refrigerant circuit and repeat the test. If quantity of refrigerant extracted roughly corresponds to specified capacity: -- Check the activation and function of the A/C compressor and the valves installed in the refrigerant circuit (shut-off valve and expansion valve). Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.-- Depending on the result, service the activation or replace the faulty component (shut-off valve, expansion valve, or A/C compressor as well as the receiver/dryer/dryer). Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- If no malfunction can be determined, there may be too much refrigerant oil in the circuit, clean the refrigerant circuit (flush with refrigerant R1234yf. Refer to REFRIGERANT CIRCUIT, CLEANING .
Final Procedures
-- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .

NOTE:

This fault may also be caused by too much refrigerant oil in the circuit. Overfilling with refrigerant oil can occur if, for example, the compressor has been replaced without adjusting the quantity of refrigerant oil.

Refer to previous notes for additional information.

Possible Deviation from Specified Value during the Pressure Test
High and low pressure normal The required cooling output is not attained in the heater and A/C unit evaporator (and in the evaporator for cooling the high-voltage components). or High and low pressure normal A/C compressor noise (particularly after switch-on) The required cooling output is not attained in the heater and A/C unit evaporator (and/or in the evaporator for cooling the high-voltage components).
Possible causes for the deviation from specified value and their solutions
One in or on the removed refrigerant circuit pressure/temperature sensor or temperature sensor sends incorrect values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM . Activation of the A/C compressor is faulty. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. If one of the valves installed in the refrigerant circuit is faulty or does not work correctly. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table . Too much refrigerant in the circuit. The expansion valve for the evaporator in the front heater and A/C unit is faulty. Too much refrigerant oil in the circuit. -- Check the measured values of the different pressure/temperature sensor and temperature sensor when operating the A/C system, and replace the components with incorrect measured values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM .-- Check the activation and function of the A/C compressor and service using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.-- Check the function and activation of the various valves and pressure/temperature sensors installed in the refrigerant circuit via the pressure distribution in the refrigerant circuit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- If no malfunction can be determined, extract the refrigerant from the refrigerant circuit. If quantity of refrigerant extracted is substantially greater than specified capacity: -- Fill the refrigerant circuit and repeat the test. If quantity of refrigerant extracted roughly corresponds to specified capacity: -- Clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING .-- Fill in correct quantity of refrigerant oil into circuit.
Final Procedures
-- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .

NOTE:

Overfilling with refrigerant oil can occur if, for example, the compressor has been replaced without adjusting the quantity of refrigerant oil.

If for example the expansion valve for the evaporator in the heater and A/C unit or for the evaporator for cooling the high-voltage battery is faulty (always open) the evaporator temperature (in the heater and A/C unit) is no longer regulated that only refrigerant in gaseous state exits from the evaporator. Under certain usage conditions, liquid droplets may then be drawn in by the compressor and cause noise (liquid cannot be compressed).

If there is too much refrigerant oil in the circuit, the compressor must be drained and the receiver/dryer must be replaced. After cleaning the refrigerant circuit (flushing with refrigerant R1234yf) and fill it with the correct quantity of refrigerant oil in the circuit. Refer to REFRIGERANT CIRCUIT, CLEANING and TECHNICAL DATA .

Refer to previous notes for additional information.

Possible Deviation from Specified Value during the Pressure Test
High and low pressure normal The required cooling output is attained in the front heater and A/C unit evaporator (and on the evaporator for cooling the high-voltage components). The required cooling output is not attained on the heater core for the heat pump output.
Possible causes for the deviation from specified value and their solutions
One in or on the removed refrigerant circuit pressure/temperature sensor or temperature sensor sends incorrect values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM . One of the pumps or one of the valves in the coolant circuit for the high-voltage system or the engine is faulty or does not function correctly. Refer to COOLANT CIRCUIT . Activation of the A/C compressor is faulty. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. If one of the valves installed in the refrigerant circuit is faulty or does not work correctly. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table . -- Check the measured values of the different pressure/temperature sensor and temperature sensor when operating the A/C system, and replace the components with incorrect measured values. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to OVERVIEW - A/C SYSTEM .-- Check the incorporation of the heat exchanger in the coolant circuit of the engine as well as the function and activation of the different pumps and valves. Refer to COOLANT CIRCUIT .-- Check the activation and function of the A/C compressor and service using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.-- Check the function and activation of the various valves and pressure/temperature sensors installed in the refrigerant circuit via the pressure distribution in the refrigerant circuit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table .-- Check the function and activation of the components for cooling the high-voltage components. Use the Vehicle Diagnostic Tester "Guided Fault Finding" for the air conditioner, the A/C Compressor and the Battery Regulation.-- If no malfunction can be determined, extract the refrigerant from the refrigerant circuit.-- Extract refrigerant from the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, DISCHARGING .-- If the extracted refrigerant quantity is significantly less than the specified capacity (more that 100g (3.5 oz) less). Refer to TECHNICAL DATA , and look for leaks and correct. Refer to LEAKS, FINDING .-- The extracted refrigerant quantity corresponds approximately to the specified capacity, check the activation of the A/C compressor and the installed shut-off valve again if no malfunction is determined. Refer to Refrigerant Circuit Refrigerant Circuit (R1234yf) Refrigerant Lines, Disconnecting And Connecting At A/C Compressor Refrigerant Circuit With Ignition Switched On, Checking Pressure Refrigerant Circuit Pressures And Temperatures Refrigerant Circuit, Cleaning Refrigerant, Filling In Reservoir Refrigerant Circuit, Charging Refrigerant Circuit, Evacuating Refrigerant Circuit, Discharging Refrigerant Gas Analysis, Performing Refrigerant Circuit, Flushing With Compressed Air Or Nitrogen Refrigerant Circuit, Cleaning Process Refrigerant Circuit, Cleaning Refrigerant Circuit, Finding Leaks Using Electronic Leak Detector Refrigerant Temperature Sensor Refrigerant Circuit Connections With Valve For Switches Refrigerant Circuit Pipes And Hoses Refrigerant Line With Inner Heat Exchanger Refrigerant Shut-Off Valves Refrigerant Circuit Layout And Function Refrigerant Circuit Components, Replacing Refrigerant R134a Vapor Pressure Table -- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .
Final Procedures
-- Charge the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, CHARGING .-- Repeat the test. Refer to ELECTRICALLY-DRIVEN A/C COMPRESSOR, CHECKING PRESSURE WITH A/C SYSTEM SWITCHED ON .

NOTE:

If the required cooling output on the evaporator in the front heater and A/C unit (and on the evaporator for cooling the high-voltage battery is OK) and there is a concern due to insufficient heating performance on the heat exchanger for the heat pump operation. The cause may be in the high-voltage system coolant circuit or in the engine coolant circuit. If the pumps and valves in the high-voltage system coolant circuit is not activated correctly or its function is not OK via the evaporator (heat exchanger) for the high-voltage system components not enough heat energy is absorbed from the coolant. If the pumps and valves in the coolant circuit of the engine are not started correctly or its function are not OK via the heat exchanger for the heat pump function for absorbing the heat energy is not transferred to the coolant flowing to the heat exchanger in the heater and A/C unit. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. Refer to COOLANT CIRCUIT .