A/C System Control and Regulation Components Inside Passenger Compartment

A/C System Control and Regulation Components Inside Passenger Compartment

• If there is a malfunction in the A/C system, first check the memory of the A/C Control Head Climatronic Control Module (J255) heater control head DTC memory using the Vehicle Diagnostic Tester in "Guided Fault Finding" function. If a different control unit displays a message to read the DTC memory, read the DTC memory on this control unit (for example, the vehicle electrical system control module (J519) , the Comfort System Central Control Module (J393) ); certain components of the A/C system (for example, the compressor regulator valve (N280) , the A/C Pressure/Temperature Sensor (G395) ) are no longer activated directly by the Climatronic control module display and control head and their measuring values are no longer evaluated directly by the Climatronic control module display and control head.

• If no fault is displayed, then read the measured value block for the Climatronic control module display and control head, and test the component using the "control diagnosis" of the Vehicle Diagnostic Tester in "Guided Fault Finding" function.

• The function "electrical testing" is not described in this Repair Manual. Perform electrical testing via "Guided Fault Finding" function. Here notes can also be found on the functions which should be tested using the Vehicle Diagnostic Tester in "Guided Fault Finding" function.

• Temperature-dependent resistance values of the various temperature sensors are stored in one table. These can be called up via the "Guided Fault Finding" function in the Vehicle Diagnostic Tester.

• Electrical checking of the various control motors is described in the guided fault-finding using the Vehicle Diagnostic Tester in "Guided Fault Finding" function.

• Servicing operations on refrigerant circuit are described in => [ Refrigerant Circuit, Servicing ] Refrigerant Circuit, Servicing.

• Perform the following work using the Vehicle Diagnostic Tester in "Guided Fault Finding" function:

- Check DTC memory of Climatronic Control Module (J255) A/C control head and erase any malfunctions displayed.

- Check the coding of the front control and display unit Climatronic Control Module.

- Check the adaptation of the front control and display unit Climatronic Control Module.

- Perform a basic setting on the A/C system.

• Components inside the passenger compartment, refer to => [ Components Inside Passenger Compartment Overview ] Components Inside Passenger Compartment Overview.