Grand Caravan V6-3.3L VIN R (2005)
Control Module HVAC: Description and Operation
Rear
Rear Blower Motor Power Module
A rear 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 rear blower motor power module is installed in the back of the rear HVAC housing, directly above the A/C expansion valve. The power 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 rear blower motor 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 lead and connector of the rear HVAC wire
harness. A second connector receptacle receives the wire harness connector from the rear blower motor. The rear 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 rear 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.
The rear blower motor power module cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
