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 repair 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 .