Commander 4WD V8-4.7L VIN N (2006)
Control Module HVAC: Description and Operation
MODULE-POWER-BLOWER MOTOR
DESCRIPTION
A 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 blower motor power module is mounted to the rear of the 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 blower motor power module is accessed for service by removing the glove box.
OPERATION
The blower motor power module is connected to the vehicle electrical system through a dedicated lead and connector of the HVAC wire harness. A
second connector receptacle receives the wire harness connector from the blower motor. The blower motor power module allows the
microprocessor-based automatic temperature control (ATC) A/C-heater 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 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 blower motor power module can be diagnosed using a scan tool.
The blower motor power module cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
