Blower Motor: Description and Operation

BLOWER MOTOR







A dual squirrel-cage blower is used (on most BMWs) to propel air across the evaporator and/or the heater core and through the plenum to the vents. On BMW A/C systems, the blower speed is controlled by resistors/transistors that vary the amount of voltage applied to the blower; depending on the air volume control knob setting. In IHKA systems, the blower speed is controlled electronically.







Whenever the A/C is switched on, the fan runs at speed "1" or higher. Without the fan working, the evaporator could ice up, as humid air comes in contact with the fins.