Blower Controls

The speed of the Blower Motor 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 Heater And A/C Control Assembly from temperature signal inputs and the operation mode of the Air Conditioning System. The Heater And A/C Control Assembly accepts input requests from the driver via the front panel pushbuttons.

The blower speed output from the Heater And A/C Control Assembly is output at terminal K. it is a continuously variable voltage proportional to blower speed. At minimum blower speed, the output is 2 to 3 volts. At maximum blower speed, the output is 7 to 10 volts.

The output speed signal from terminal K is input to the Blower Control Module at terminal B on connector C2. An amplifier and driver circuit in the Blower Control Module supply a voltage of between 4 and 12 volts to the Blower Motor according to the input signal at terminal B.

The voltage at the Blower Motor is fed back to the Heater and A/C Control Assembly at terminal L, allowing precise speed control of the blower by the circuits in the Heater And A/C Control Assembly.