Blower Controls

The 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 in the OFF position, all the blower relays de-energize. In this state, a voltage path through the relay contacts to the blower motor does not exist. The blower motor does not run.

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

With medium #1 blower speed selected, the 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, the current flow is the same as in medium #1. In addition, a parallel current path goes through resistor (B) and the 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. Relay No. 3 provides a parallel battery feed circuit to the blower motor.