Notes On A/C System Control And Regulation In Passenger Compartment

If There Is A Malfunction In The A/C System, First Check The DTC Memory Of The Climatronic Control Module -J255- A/C Display And Control Head, Using The Vehicle Diagnostic Tester In The "Guided Fault Finding  " Function. If a different control module displays a message to read the DTC memory, also read the DTC memory for this control module (for example, the Vehicle Electrical System Control Module -J519-, the Comfort System Central Control Module -J393-); certain A/C system components (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 -J255- A/C display and control head and their measuring values are no longer evaluated directly by the Climatronic Control Module -J255- A/C display and control head.

If no fault is displayed, read the measured value block for the Climatronic Control Module -J255- A/C display and control head and activate the potentially defective component with the "output diagnosis test mode" function, using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function.

The function "electrical testing" is not described in this service information. Perform an electrical test via the "Guided Fault Finding  " function, here can notes also be found on the functions which should be tested, using the Vehicle Diagnostic Tester in the "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, using the Vehicle Diagnostic Tester in the "Guided Fault Finding  " function.

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

Repair Work On Refrigerant Circuit Are Described. Refer To REFRIGERANT CIRCUIT .