Blower Motor: Description and Operation

Blower Motor - Description:

The blower motor is a 12-volt, direct current (DC) motor mounted within a plastic housing with an integral wire harness connector and squirrel cage-type blower wheel that is secured to the blower motor shaft. The blower motor wheel is located in the HVAC air inlet housing which is on the passenger side end of the HVAC housing. The blower motor can be accessed for service from underneath the instrument panel.

The blower motor controls the velocity of air moving through the HVAC housing by spinning the blower wheel within the HVAC air inlet housing at the selected speed or, in the automatic temperature control (ATC) system, at the selected or programmed speed.

Blower motor speed for the MTC system is controlled by regulating the blower motor ground path through the blower motor resistor and through the blower motor control located within the MTC A/Cheater control. The blower motor will operate whenever the ignition switch is in the Run position and the blower motor control in any position except Off. For the ATC system, blower motor speed is controlled by the body control module (BCM). The BCM varies the duty cycle supplied by the blower motor power module to a fixed frequency output (pulse width modulation) as requested by the ATC blower motor control (manual mode) or by sensor data (automatic mode). The blower motor will operate whenever the ignition switch is in the Run position and the A/C-heater control power is turned on.

The blower motor and blower motor wheel are factory balanced and cannot be adjusted or repaired. If faulty or damaged, the blower motor and blower wheel must be replaced as an assembly.