With Electronic A/C

CIRCUIT OPERATION
The speed of the Blower Motor is determined by the voltage applied to the motor. At low blower speeds the applied voltage is about 4 volts. As the voltage is increased, the blower speed increases until maximum blower speed is reached at 12 volts.

The speed at which the blower runs 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 by the front panel push-buttons.

The blower speed output from the Heater and A/C Control Assembly is at Terminal C4 and is a continuously variable voltage, proportional to blower speed. At minimum blower speed the output is about 2.5 volts and at maximum blower speed it is about 7 volts.

The output speed signal from Terminal C4 is an input to the Blower Control Module at Terminal B of connector C2. An amplifier and driver circuit in the Blower Control Module supplies voltage 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 C5.