Grand Caravan V6-3.3L VIN R (2005)
Control Module HVAC: Description and Operation
Front
Front Blower Power Module
A front blower motor power module is used on this model when it is equipped with the automatic temperature control (ATC) heating-A/C system.
Models equipped with the manual temperature control (MTC) heating-A/C system use a blower motor resistor, instead of the blower motor power
module.
The front blower motor power module is mounted to the rear of the front HVAC housing, directly behind the glove box. The blower motor power
module consists of a molded plastic mounting plate with two integral connector receptacles (1). Concealed behind the mounting plate is the power
module electronic circuitry and a large finned heat sink (2). The front blower motor power module is accessed for service by removing the glove box.
The front blower motor power module is connected to the vehicle electrical system through a dedicated lead and connector of the front HVAC wire
harness. A second connector receptacle receives the wire harness connector from the front blower motor. The front blower motor power module allows
the microprocessor-based automatic temperature control (ATC) A/Cheater control 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 front blower motor feedback voltage. The resulting
output drives the power module circuitry, which provides a linear output voltage to change or maintain the desired blower speed.
The front blower motor power module is diagnosed using a DRBIII(R) scan tool.
The front blower motor power module cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
