Blower Controls

The Blower Motor control circuit consists of the following components: Blower Motor, HVAC Programmer, Blower Control Module, Heater And A/C Control Assembly and Steering Wheel Controls (if equipped).

The Blower's speed is determined by the voltage applied to the motor. At low Blower Motor speeds, the applied voltage is about 4 volts. As the voltage increases, the Blower Motor speed increases until the maximum Blower speed is reached. At maximum speed, the applied voltage is about 12 volts.

Blower speed is controlled by the HVAC Programmer from temperature signal inputs and the operation mode of the Air Conditioning System. The system's driver selected operation mode is communicated to the HVAC Programmer from the Heater And A/C Control Assembly and Steering Wheel Controls (if equipped) through the E & C Data Line.

The Blower speed output from the HVAC Programmer is a continuously variable voltage proportional to Blower speed. At minimum Blower speed, the output is 2-3 volts. At maximum Blower speed, the output is 7-10 volts.

The output signal from the HVAC Programmer is input to the Blower Control Module. An amplifier and driver circuit in the Blower Control Module supply a voltage of between 4-12 volts to the Blower Motor.

The voltage at the Blower Motor is fed back to the HVAC Programmer. This allows precise speed control of the Blower by the HVAC Programmer.