With Electronic Controls

Blower motor speed is determined by the voltage applied to the motor. This voltage varies from approximately 4 volts (low speed) to approximately 12 volts (high speed). The voltage applied to the blower motor is controlled by the Heater-A/C Control. The blower motor speed can be adjusted manually by pressing the "FAN" up or down switches or automatically by placing the Heater-A/C Control in the "AUTO" mode. The Heater-A/C Control sends blower request information to the Blower Motor Control Module in the form of a variable voltage signal. This voltage signal ranges from approximately 0.5 volts, for low speed, to approximately 7 volts, for high speed. An amplifier and driver circuit in the Blower Motor Control Module supplies from 4 to 12 volts to the blower motor according to the request signal from the Heater-A/C Control. Blower motor voltage is also fed back to the Heater-A/C Control to maintain blower speed stability and to indicate any failure in the blower motor circuitry.