Operation CHARM: Car repair manuals for everyone.

Control Module HVAC: Description and Operation

The blower speed control is located on the evaporator housing in the engine compartment.
- The function of the 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.
- The 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.