Blower Motor: Description and Operation

Battery voltage is supplied at all times to the No. 1 blower relay through the HTR A/C fuse and the RED wire. When the control assembly is OFF, all blower relays are de-energized. In this state there is no voltage path through the relay contacts to the blower motor. The blower motor does not run.

With low blower speed selected, current flows through the No. 1 relay, to the top of the resistor board (A) and both resistors.

With medium # 1 blower speed selected, current flows through the No. 1 relay, to the No. 2 relay, to the center of the resistor board (A) and one resistor to the motor.

With medium # 2 blower speed selected, current flow is the same as in medium # 1 in addition, a parallel current path goes through resistor (B) and No. 3 blower relay to the blower motor. This provides a parallel path with a value less than one alone, but more voltage than for medium #1 blower speed.

With high blower speed selected, No. 1 and No. 2 blower relays are off. Relay No. 3 is on, and provides a parallel battery feed circuit to the blower motor.