Rear Power Module

POWER MODULE - REAR BLOWER MOTOR
A rear 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 rear blower motor power module is installed in the back of the rear HVAC housing, directly above the expansion valve. The module consists of a molded plastic mounting plate with two integral connector receptacles. Concealed behind the mounting plate within the evaporator housing is the power module electronic circuitry and a large finned, heat sink. The power module is accessed for service by removing the right quarter and D-pillar trim panels.

The rear blower motor power module is connected to the vehicle electrical system through a dedicated take out and connector of the rear HVAC wire harness. A second connector receptacle receives the pigtail wire connector from the rear blower motor. The rear 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 rear blower motor relay to change or maintain the desired blower speed. The rear blower motor power module is diagnosed using a DRBIII(R) scan tool. Refer to Body Diagnostic Procedures.