Possible deviation from specified value during the pressure test (17 Of 32)
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| Possible deviation from specified value during the pressure test |
- The required cooling output is not attained in the heater and A/C unit evaporator (and in the evaporator for battery cooling).
- The required cooling output is only not attained at the heater and A/C unit evaporator (the cooling output on the evaporator for the cooling output is OK).
- The high pressure only falls slightly (via the pressure with the A/C compressor stopped) or corresponds to the specified value.
- Low pressure quickly drops to target value or lower.
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| Possible causes for the deviation from specified value and their solutions |
- There is too little refrigerant in the refrigerant circuit.
-- Extract refrigerant from the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, DISCHARGING
.-- If the extracted refrigerant quantity is substantially smaller (more than 100 g) than the specified capacity. (refer to TECHNICAL DATA
(vehicle-specific service information), there is too much refrigerant in the refrigerant circuit. Refer to LEAKS, FINDING
.-- If the extracted refrigerant quantity corresponds to the capacity or is only slightly smaller (maximum 100 g). (refer to TECHNICAL DATA
(vehicle-specific service information)) check the expansion valve and shut-off valve for function. Refer to REFRIGERANT CIRCUIT
(vehicle-specific service information).
- The expansion valve for the evaporator in the heater and A/C unit is faulty. Refer to REFRIGERANT CIRCUIT
(vehicle-specific service information).
- A Refrigerant Shut-Off Valves -- is faulty (closed), check the function. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding
" function for the A/C system and the battery regulation and refer to REFRIGERANT CIRCUIT
(vehicle-specific service information) for replacing.
-- If equipped, check the function of the installed shut-off valve. Refer to REFRIGERANT CIRCUIT
(vehicle-specific service information).-- Replace the expansion valve for the evaporator in the heater and A/C unit. Refer to REFRIGERANT CIRCUIT
(vehicle-specific service information).
- Constriction or blockage in the refrigerant circuit (for example in the refrigerant line between the "low pressure side" service connection and the A/C compressor). Refer to REFRIGERANT CIRCUIT
(vehicle-specific service information).
- Activation of the A/C compressor is malfunctioning. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding
" function for the A/C system and the battery regulation.
-- Check the activation and function of the A/C compressor and service. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding
" function of the A/C system and the battery regulation. If not error can be determined run hand over refrigerant circuit to check for differences in temperature. Refer to REFRIGERANT CIRCUIT
(vehicle-specific service information).-- If difference in temperature is found at one component: If the hose or pipe is kinked or constricted, replace this component and replace a faulty expansion valve. Refer to REFRIGERANT CIRCUIT
(vehicle-specific service information). If there is a blockage clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING
.-- If there is a blockage clean the refrigerant circuit (flush with refrigerant R1234yf). Refer to REFRIGERANT CIRCUIT, CLEANING
. Replace the expansion valve for the evaporator in the heater and A/C unit (and for the evaporator for battery cooling) as well as the desiccant bag/dryer cartridge (or reservoir/receiver/dryer). Refer to COMPONENTS, REPLACING
and REFRIGERANT CIRCUIT
(vehicle-specific service information). |
| 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 . |