Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Module, Power, Blower Motor: 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 lead and connector of the wire harness is connected to the blower motor.
On the Automatic Temperature Control (ATC) system, the blower motor power module allows the microprocessor-based Heater, Ventilation and Air Conditioning (HVAC) module to calculate and provide infinitely variable blower motor speeds based upon either manual blower switch input or the ATC programming.
On the Manual Temperature Control (MTC) system, the blower motor power module allows the HVAC module to provide a wide range of blower motor speeds throughout its operating range, based upon blower switch input.
Both the ATC and MTC systems use a Pulse Width Modulated (PWM) circuit strategy. 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. Refer to DTC INDEX (1 OF 2) and/or DTC INDEX (2 OF 2) .
The blower motor power module cannot be adjusted or repaired and must be replaced if inoperative or damaged.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.