if The Target Values Are Not Reached, Check The Following:
- Coolant circuit bleeding. Refer to COOLANT CIRCUIT FILLING AND BLEEDING [CRUA, DEJA] / COOLANT, FILLING (BLEEDING) [CNSB, CNTC] .
- Incorporation Of The Heater Core For The Heater Into Coolant Circuit. Refer to COOLING SYSTEM/COOLANT [CRUA, DEJA] / COOLANT SYSTEM/COOLANT [CNSB, CNTC] (Connection Diagram for Coolant Hoses).
- Foam seal on the heater core for the heater. Refer to HEATER CORE, REMOVING AND INSTALLING .
- Actuation and function of the Left Temperature Door Motor -V158- and the Right Temperature Door Motor -V159-. Use the :Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
- Measured values for the Left Vent Temperature Sensor -G150- /Right Vent Temperature Sensor -G151- /Footwell Vent Temperature Sensor -G192-. Use the :Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
- Function of the temperature doors for the left and right side in the A/C unit. Refer to AIR DISTRIBUTION HOUSING, REMOVING AND INSTALLING .
- Engine Coolant Thermostat. The engine coolant may not heat properly if the coolant thermostat is faulty. Refer to COOLANT PUMP/COOLANT THERMOSTAT [CNSB, CNTC] / COOLANT PUMP/THERMOSTAT [CRUA, DEJA] / COOLANT THERMOSTAT, CHECKING [CRUA, DEJA] (Coolant Thermostat, Checking) or use the Vehicle Diagnostic Tester (depending on the engine).
- Engine coolant pump. Refer to COOLANT PUMP/COOLANT THERMOSTAT [CNSB, CNTC] / COOLANT PUMP/THERMOSTAT [CRUA, DEJA] (Coolant Pump Overview).
- If installed: Check the After-Run Coolant Pump -V51- / Heater Support Pump -V488- (different designations, depending on the engine) and the Coolant Shut-Off Valve -N82- function. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
For vehicles with an After-Run Coolant Pump -V51- / Heater Support Pump -V488- (different designations, depending on the engine), bring the engine RPM 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 rate of the engine coolant pump is too low while idling or the incorporation of the heater core for the heater into the coolant circuit is not according to the specification. Refer to COOLING SYSTEM/COOLANT [CRUA, DEJA] / COOLANT SYSTEM/COOLANT [CNSB, CNTC] (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 highest possible temperature for the front passenger side.
- Set the temperature preset "warm" via the regulator -7- : "HI" for the front passenger side in the display -3- on the Climatronic Control Module -J255-.
-- "Read measured values" for the Left Vent Temperature Sensor -G150- /Right Vent Temperature Sensor -G151- /Footwell Vent Temperature Sensor -G192-.
Target values with an engine temperature of about 90 °C (194 °F):
- The temperature increases to above 55 °C (131 °F) in the display field with the measured value for the Right Vent Temperature Sensor -G151-.
- The deviation between the display fields for the measured values of the Left Vent Temperature Sensor -G150- /Right Vent Temperature Sensor -G151- /Footwell Vent Temperature Sensor -G192- is less than 8 °C (46.4 °F).
If the target values are not reached, check the components as described above. Refer to if The Target Values Are Not Reached, Check The Following: .
-- Set the lowest possible temperature for the driver and front passenger side.
- Set the temperature preset "cold" via the regulators -1 and 7- : "LO" for the driver and front passenger side in the display -3- on the Climatronic Control Module -J255-.
-- "Read measure values" for the Left Vent Temperature Sensor -G150- /Right Vent Temperature Sensor -G151- /Footwell Vent Temperature Sensor -G192- and Evaporator Vent Temperature Sensor -G263-.
-- Compare the Left Vent Temperature Sensor -G150- /Right Vent Temperature Sensor -G151- /Footwell Vent Temperature Sensor -G192- measured values with the measured value for the Evaporator Vent Temperature Sensor -G263-.
Specified Values:
- The measured values for the Left Vent Temperature Sensor -G150- /Right Vent Temperature Sensor -G151- /Footwell Vent Temperature Sensor -G192- must not be smaller and after five minutes be greater than maximum 7 °C (44.6 °F) than the value for the Evaporator Vent Temperature Sensor -G263-. Use the :Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
- The deviation between the measured values for the Left Vent Temperature Sensor -G150- /Right Vent Temperature Sensor -G151- /Footwell Vent Temperature Sensor -G192- must not be greater than 8 °C (46.4 °F).
if The Target Values Are Not Reached, Check The Following:
- Actuation and function of the Left Temperature Door Motor -V158- and the Right Temperature Door Motor -V159-. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" function.
- Function of the temperature doors for the left and right side in the A/C unit. Refer to AIR DISTRIBUTION HOUSING, REMOVING AND INSTALLING .
- Foam seal on the heater core for the heater. Refer to HEATER CORE, REMOVING AND INSTALLING .
- Check the measured values for the Left Vent Temperature Sensor -G150- /Right Vent Temperature Sensor -G151- /Footwell Vent Temperature Sensor -G192- and Evaporator Vent Temperature Sensor -G263-. Use the Vehicle Diagnostic Tester in the"Guided Fault Finding" function.