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 of 12 volts is reached.

Blower speed is determined by the Heater and A/C Control Assembly from temperature signal inputs and the operating 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.