Operation CHARM: Car repair manuals for everyone.

Blower Control Module


The blower control module is a solid state device that operates the blower motor. The blower control module outputs a voltage that varies between 0 volts (blower motor OFF) and 12 volts (maximum blower motor speed).

To determine the appropriate output voltage, the blower control module monitors a pulse width modulated voltage signal from the HVAC programmer. The module then amplifies the signal and applies voltage directly to the blower motor.