Blower Motor and Squirrel Cages

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