Grand Cherokee 2WD V6-3.7L (2008)
Control Module HVAC: Description and Operation
Blower Motor Power Module - Operation
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 is diagnosed using a scan tool .
The blower motor power module cannot be adjusted or repaired and must be replaced if found inoperative or damaged.
