A/C System Control and Regulation Components Outside Passenger Compartment

A/C System Control and Regulation Components Outside Passenger Compartment

• If there is a malfunction in the A/C system, first check the event memory of the Climatronic Control Module (J255) (and the Rear A/C Display Control Head (E265) ) refer to the Vehicle Diagnostic Tester in the "Guided Fault Finding" function. If a different control unit displays a message to read the event memory, also read the event memory on this control module (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 A/C Compressor Regulator Valve (N280) , the A/C Pressure/Temperature Sensor (G395) ) are no longer activated directly by the Climatronic control module and the measured values are no longer evaluated directly by the Climatronic control module.

• If no malfunction is displayed, read the relevant measured value block for the Climatronic control module (and the rear A/C display control head) and activate a potentially problematic component via the "output DTM" function of the Vehicle Diagnostic Tester.

• The function "electrical testing" is not described in this repair information. Perform the electrical test using the "Guided Fault Finding" function. This also contains information regarding the functions to be tested using the Vehicle Diagnostic Tester.

• The temperature-dependent resistance values for the various temperature sensors are in tables. They can be accessed using the "Guided Fault Finding" function of the Vehicle Diagnostic Tester.

• The electrical test of the different control motors is described in Guided Fault Finding of the Vehicle Diagnostic Tester.

• Servicing operations for the refrigerant circuit are described in => [ Refrigerant Circuit, Servicing ] Refrigerant Circuit, Servicing and => [ Refrigerant Circuit Components Overview ] Refrigerant Circuit Components Overview.

• Perform the following work on completion of repair operations:

- Check the event memory of the Climatronic control module (and the rear A/C display control head) and erase any displayed malfunctions using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

- Check the coding of the Climatronic control module (and the rear A/C display control head) using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

- Check the adaptation of the Climatronic control module (and the rear A/C display control head) using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

- Perform the basic setting of the Climatronic control module (and the rear A/C display control head) using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

• Coolant hoses from connections to A/C unit heater core, removing and installing, refer to => [ Heater Core With Front A/C Unit Installed ] Heater Core With Front A/C Unit Installed.

• A/C unit heater core connection in engine coolant circuit.

• Depending on vehicle production period, connection points may be installed in refrigerant lines on certain versions (not planned at this time, introduction not yet finalized). Refer to the Electronic Parts Catalog. As with connections on various components, these connection points may only be loosened and opened when the refrigerant circuit is empty, refer to => [ Refrigerant Circuit, Servicing ] Refrigerant Circuit, Servicing.

• Components on the vehicle front and in the engine compartment, refer to => [ Vehicle Front and Engine Compartment Components ] Vehicle Front and Engine Compartment Components.

• Components of the refrigerant circuit and coolant circuit, refer to => [ Refrigerant and Coolant Circuits Components and Plenum Chamber Water Drains ] Refrigerant and Coolant Circuits Components and Plenum Chamber Water Drains.

• Components on the vehicle rear and in the luggage compartment, refer to => [ Vehicle Rear and Luggage Compartment Components ] Vehicle Rear and Luggage Compartment Components.