Condenser Fan: Description and Operation

Condenser Fan (radiator fan)

NOTE: The air throughput is influenced by the back pressure which arises in the area of the fresh air inlet according to the vehicle speed. In order to compensate for this dependency, the distributor flap for fresh air/recirculated air (back pressure flap) is moved in the direction of "closed" (recirculated air) according to the vehicle speed (from 56 mph/90 km/h). The flap setting is also dependent on the fan voltage.

The required speed for the cooler fan is calculated in the DME engine control unit according to the refrigerant pressure (supplied via CAN from the a/c control panel) and the coolant temperature sensor (see also section "DME"). The DME control unit sends this speed data via CAN Drive to the gateway and via CAN Comfort to the front end control unit. The front end control unit controls the radiator fans (right and left) together via an output module. To this end, the front end controller transmits a pulse width modulated (PWM) signal to this output module. The output module evaluates and processes the PWM signal and relays it to the fans.

For the purposes of the air conditioning system, the fans are controlled in linear mode according to the recorded value from the coolant pressure sensor.