Control Module HVAC: Description and Operation

Blower Motor Power Module
Models equipped with the optional Automatic Temperature Control (ATC) system have a blower motor power module. The power module allows the selection of almost infinitely variable blower motor speeds. The power module is mounted to the heater-A/C housing, under the instrument panel and just inboard of the blower motor, in the same location used for the blower motor resistor on manual temperature control systems. It can be accessed without removing any other components.

The blower motor power module output to the blower motor can be controlled by adjusting the blower motor speed switch knob on the ATC heater-A/C control panel, or it can be adjusted automatically by the logic circuitry and programming of the ATC control module. In either case, the ATC control module sends the correct pulse-width modulated signal to the power module to obtain the selected or programmed blower motor speed.

The blower motor power module cannot be repaired and, if faulty or damaged, it must be replaced.