Auxiliary Fan Control

The auxiliary fan motor incorporates an output final stage that activates the fan motor at variable speeds. The auxiliary fan is controlled by the MS S52. The motor output stage receives power and ground and activates the motor based on a PWM signal (10-100 Hz) received from the MS S52. Similar to the auxiliary fan in the E46 with MS 42.0 control, the fan speed or activation is based on radiator outlet temperature sensor input exceeds a preset temperature, IHKA signalling via the "K" and CAN bus based on calculated refrigerant pressures, vehicle speed and battery voltage level. When the over temperature light in the instrument cluster is on 248°F (120°C) the fan is run in the overrun function. This signal is provided to the PCM via the CAN bus. When this occurs the fan is run at a frequency of 10 Hz. See Figure.