Control Module HVAC: Description and Operation

BLOWER MOTOR SPEED CONTROL

Models equipped with the optional Automatic Zone Control (AZC) system have a blower motor controller (power module). The controller allows the selection of almost infinitely variable blower motor speeds. The controller 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 controller output to the blower motor can be adjusted by the blower motor speed switch knob on the AZC heater-A/C control panel, or it can be adjusted automatically by the logic circuitry and programming of the AZC control module. In either case, the AZC 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 controller cannot be repaired and, if faulty or damaged, it must be replaced.