Blower Motor Power Module

POWER MODULE - BLOWER MOTOR
A blower motor power module is used on this model when it is equipped with the optional Automatic Temperature Control (ATC) system. Models equipped with the standard manual heater-A/C system use a blower motor resistor
block, instead of the blower motor power module.

The blower motor power module is mounted to the rear of the HVAC housing, directly behind the glove box opening in the instrument panel. The module
consists of a molded plastic mounting plate with two integral connector receptacles. Concealed behind the mounting plate is the power module electronic circuitry and a large finned, heat sink. The blower motor power module is accessed for service by removing the glove box from the instrument panel.

The blower motor power module is connected to the vehicle electrical system through a dedicated lead and connector from the instrument panel wire harness. A second connector receptacle receives a wire lead connector from the blower motor. The blower motor power module allows the microprocessor-based Automatic Temperature Control (ATC) heater-A/C control module to calculate and provide infinitely variable blower motor speeds based upon either manual blower switch input or the ATC programming using a Pulse Width Modulated (PWM) circuit strategy. The PWM voltage is applied to a comparator circuit which compares the PWM signal voltage to the blower motor feedback voltage. The resulting output drives the power module circuitry, which adjusts the voltage output received from the blower motor relay to change or maintain the desired blower speed. The blower motor power module is diagnosed using a DRBIII(R) scan tool. Refer to Body Diagnostic Procedures.