Control Module HVAC: Testing and Inspection

A/C Components Controlled or Activated by Other Control Modules, Electrical Tests

• Different A/C components are not controlled directly by the Climatronic Control Head (J255). The A/C compressor regulator valve (N280) , for example, is controlled by the vehicle electrical system control module (J519). The data is exchanged via the databus system between both control modules. Check using the Vehicle diagnostic tester in "Guided Fault Finding".

• The measured values on the different A/C components are not evaluated directly by the Climatronic control module. For example, the pressure signal from the A/C Pressure/Temperature Sensor (G395) is evaluated from the Vehicle Electrical System Control Module and the measured values are sent via the data bus system to the Climatronic control module. Check using the Vehicle diagnostic tester in "Guided Fault Finding" function and the.

• From MY 2010, some vehicles have a Start/Stop System for specific engines as optional equipment. The setting on the Climatronic control module can prevent the Stop function. If, for example, "defrost" is selected, the stop function is not possible or will be interrupted and the engine will start. The same applies in the case of heating and cooling. The difference between the selected and actual temperature is greater than a specified value. Check using the Vehicle diagnostic tester in "Guided Fault Finding".