Vehicles With Manually Regulated A/C System

Vehicles With Manually Regulated A/C System

A/C Control Module (J301) activation

• By pressing the button - E - with the ignition switched on, the Vehicle electrical system control module (J519) is activated (by the A/C control module (J301) via the Data bus). As soon as the vehicle electrical system control module switches on the rear window defroster (only when the engine is running), the indicator lamp in the button - E - comes on (the vehicle electrical system control module sends the request via the Data bus). Rear window heater is switched off by pressing button - E - again and by switching ignition off. Refer to and Owners manual.






• If the voltage measured on the vehicle electrical system control module to terminal 30 below the valued stored in the vehicle electrical system control module, then the activation of the rear window defogger (Z1) will be switched off completely and this will relieve the load on the generator. Check using Vehicle diagnosis, testing and information system (VAS5051B) in "Guided Fault Finding" function.

• The rear window defogger is controlled by the vehicle electrical system control module only when the engine is running. If the engine is not running, there is no control and there is no request from the vehicle electrical system control module. The LED in the button - E - does not come on, or will go out shortly after the button is pressed.

• If rear window defogger must be switched off for a short time by vehicle electrical system control module due to insufficient voltage, indicator lamp in heated rear window button - E - remains switched on, if switch-off is prolonged however, vehicle electrical system control module switches off the indicator lamp.

• Function test of heated rear window activation is described in Guided Fault Finding for vehicle electrical system control module and for A/C system using Vehicle diagnosis, testing and information system (VAS5051B) in "Guided Fault Finding" function.

• The function and the control of the heated rear window is displayed in the measured values block of the A/C control module (J301). Check using Vehicle diagnosis, testing and information system (VAS5051B) in "Guided Fault Finding" function.

• The rear window defogger switches itself off when the outside air temperature is higher than 0 °C and after about 10 minutes by the vehicle electrical system control module.

• The heated rear window stays switched on with outside temperatures up to 0 °C until ignition is switched off (heated rear window can be switched off and back on manually at anytime). If the temperature increases above 0 °C during a driving cycle, the heated rear window will be switched off after the specified operating time stored in vehicle electrical system control module (approximately 10 minutes) has elapsed.