Operation CHARM: Car repair manuals for everyone.
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Control Module HVAC: Description and Operation

The A/C blower motor speed control is located on the A/C evaporator housing, in the engine compartment.
- The function of the A/C blower motor speed control is to convert low power signals from the electronic automatic temperature control module to a high current, variable ground feed for the blower motor.
- Blower motor speed is infinitely variable and is controlled by the electronic automatic temperature control module software.
- A delay function provides a gradual increase or decrease in blower motor speed under all conditions.