Heating Output And Temperature Control Door Activation, Checking, Vehicles Without A/C System
Refer to HEAT OUTPUT TEST INFORMATION AND TOOLS REQUIRED
Test Requirements
- Coolant circuit bled according to specifications. Refer to COOLANT, DRAINING AND FILLING [DAZA] / COOLANT, DRAINING AND FILLING [CNTC, CYFB] .
- All air ducts, covers and seals are OK and properly installed.
- Seal between engine compartment, hood and plenum chamber is OK and installed correctly. Refer to Bulkhead ; (Overview - Plenum Chamber Cover) to check.
- If installed: After-Run Coolant Pump -V51- and Coolant Shut-Off Valve -N82- function is OK.
- The airflow through the dust and pollen filter is not obstructed by dirt. Refer to DUST AND POLLEN FILTER, REMOVING AND INSTALLING to check.
- The air intake for the heater (in fresh air and recirculating air mode) is not obstructed by dirt or retrofitted components.
- The vehicle is not exposed to sunlight.
- Engine is warm; coolant temperature is greater than 80 °C (176 °F).
- The DTC memory for the Climatronic Control Module -J255- was checked and erased and the basic setting was performed using the Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
- The coding and adaptation of the Climatronic Control Module -J255- was checked using the Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
- Vehicles with TDI engine: Activation and function of the Auxiliary Heater Heating Element -Z35- is OK. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
- Vehicles with a gasoline engine and an Auxiliary Heater Heating Element -Z35- (introduction not yet finalized): Activation and function of the Auxiliary Heater Heating Element -Z35- is OK. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
Checking
-- Close the hood, doors, windows and sliding sunroof.
-- Open all instrument panel vents.
-- Start the engine and adjust the following settings on the control heads:
This illustration shows the layout of the regulators -1, 2 and 3- and the buttons -4 and 5- on a left-hand drive vehicle with a manual climate control system. The layout may be different on a right-hand drive vehicle.
A Front A/C Display Control Head 3 -E776- -2- without an A/C button is installed on vehicles without an A/C system (with heating only). Refer to the Parts Information.
The designations on the display control heads -1- and -3- should actually read "Heating". However, since heating without an A/C system is only offered in a few markets, the designation "A/C system" was kept for the heating.
-- Start the engine and adjust the following settings on the heater display control heads:
- Turn the regulator -1- (Front A/C Display Control Head 2 -E775-) for the fresh air blower to the maximum speed.
- Turn the regulator -2- (Front A/C Display Control Head 3 -E776-) for the temperature setting to the "cold" stop.
- Turn the regulator -3- (Front A/C Display Control Head 4 -E777-) for air distribution to "instrument panel vent".
- Recirculating air mode off: The indicator lamp in the Fresh Air and Recirculating Air Mode Button -E781- -4- does not come on.
-- Let the heater run several minutes at this setting with the engine running.
-- Measure the ambient temperature.
-- Measure the temperature of the air coming out of the left and right instrument panel vents with a thermometer.
-- Compare the measured values with the displayed measured value for the Evaporator Vent Temperature Sensor -G263-. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" function (for the Climatronic Control Module -J255-).
Specified Values:
- After five minutes the measured value for the Evaporator Vent Temperature Sensor -G263- may be a maximum of 15 °C (59 °F) greater than the measured ambient temperature.
- The measured values for the air temperature from the left and right vents must not be lower than the measured value of the Evaporator Vent Temperature Sensor -G263- and also not greater than a maximum of 7 °C (45 °F) after five minutes. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
- The deviation of the measured air temperatures from the left and right vents is less than 8 °C (47 °F).
If the measured values for the temperature of the air coming out of the vents is less than the measured value for the Evaporator Vent Temperature Sensor -G263-, this indicates a faulty temperature sensor.
If the specified values are not reached, check the following:
- Check the seal between the engine compartment, hood and plenum chamber and repair if necessary. Refer to Bulkhead ; (Overview - Plenum Chamber Cover).
- Repeat the test while measuring the temperature of the air drawn in via the fresh air intake for the heater in the plenum chamber with one of the two temperature sensors with the hood closed. The permissible increase of air temperature in the heater (between the air intake in the fresh air intake and the air outlet from the instrument panel vents) is a maximum of 10 °C (50 °F).
If the temperature in the heater increases more than 10 °C (50 °F), check the following:
- Activation and function of the Temperature Control Door Motor -V68- using the Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
- Function of the temperature control door in the heater. Refer to OVERVIEW - AIR DISTRIBUTION HOUSING DOORS AND SEPARATORS .
- Foam seal on the heater core for the heater. Refer to HEATER CORE, REMOVING AND INSTALLING .
-- Set the highest possible temperature.
- Turn the regulator -2- (Front A/C Display Control Head 3 -E776-) for the temperature setting to the "warm" stop.
-- Measure the temperature of the air coming out of the left and right instrument panel vents with a thermometer.
Specified values with an engine temperature of approximately 90 °C (194 °F):
- The temperature of the air from the instrument panel vents goes above 55 °C (131 °F).
- The temperature deviation between the left and right side is less than 8 °C (46 °F).
If the specified values are not reached, check the following:
- Coolant circuit bleeding. Refer to COOLANT, DRAINING AND FILLING [DAZA] / COOLANT, DRAINING AND FILLING [CNTC, CYFB] .
- Incorporation of the heater core for the heater into the coolant circuit. Refer to COOLANT SYSTEM/COOLANT [DAZA] / COOLANT SYSTEM/COOLANT [CNTC, CYFB] (Connection Diagram for Coolant Hoses).
- Foam seal on the heater core for the heater. Refer to HEATER CORE, REMOVING AND INSTALLING .
- Activation and function of the Temperature Control Door Motor -V68- using the Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
- Function of the temperature control door in the heater. Refer to OVERVIEW - AIR DISTRIBUTION HOUSING DOORS AND SEPARATORS .
- Engine coolant thermostat. The engine coolant may not heat properly if the coolant thermostat is faulty. Refer to COOLANT PUMP/COOLANT THERMOSTAT [DAZA] / COOLANT PUMP/COOLANT THERMOSTAT [CNTC, CYFB] (Coolant Thermostat, Checking).
- Engine coolant pump. Refer to COOLANT PUMP/COOLANT THERMOSTAT [DAZA] / COOLANT PUMP/COOLANT THERMOSTAT [CNTC, CYFB] (Overview - Coolant Pump).
- If installed: Check the function of the After-Run Coolant Pump -V51- and the Coolant Shut-Off Valve -N82- using the Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
For vehicles without an After-Run Coolant Pump -V51-, set the engine speed to approximately 2000 RPM and repeat the test if necessary. If the air temperature goes above 55 °C (131 °F) when repeating the test at a higher engine speed, this indicates that there is too little coolant flowing through the heater core for the heater. Cause: The delivery quantity of the engine coolant pump is too low at idle speed, or the incorporation of the heater core for the heater in the coolant circuit is not according to the specification. Refer to COOLANT SYSTEM/COOLANT [DAZA] / COOLANT SYSTEM/COOLANT [CNTC, CYFB] (Connection Diagram for Coolant Hoses).
If too little warmed up coolant flows through the heater core for the heater, the required heat output is not reached.
-- Set the lowest possible temperature.
- Turn the regulator -2- (Front A/C Display Control Head 3 -E776-) for the temperature setting to the "cold" stop.
-- Measure the temperature of the air coming out of the left and right instrument panel vents with a thermometer.
Specified Values:
- After five minutes the measured value for the Evaporator Vent Temperature Sensor -G263- may be a maximum of 15 °C (59 °F) greater than the measured ambient temperature.
- The measured values for the air temperature from the left and right vents must not be lower than the measured value of the Evaporator Vent Temperature Sensor -G263- and also not greater than a maximum of 7 °C (45 °F) after five minutes. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
- The deviation of the measured air temperatures from the left and right vents is less than 8 °C (46 °F).
If the specified values are not reached, check the following:
- Activation and function of the Temperature Control Door Motor -V68- using the Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
- Function of the temperature control door in the heater. Refer to OVERVIEW - AIR DISTRIBUTION HOUSING DOORS AND SEPARATORS .
- Foam seal on the heater core for the heater. Refer to HEATER CORE, REMOVING AND INSTALLING .
- Measured value for the Evaporator Vent Temperature Sensor -G263- using the Vehicle Diagnostic Tester in the"Guided Fault Finding" function.