Heater Without A/C

Battery voltage is supplied when the Ignition Switch is in RUN to Relay Coil Pin 5 of each of the three Rear Blower Relays through the BRN (341) wire. Battery voltage is also supplied when the Ignition Switch is in RUN to Pin 1 of each of the three Rear Blower Relays through the RED (542) wire. With the Rear Auxiliary Heater Control Switch in OFF, no grounding path is provided for the Relay Coils and the relays remain de-energized. The relay contacts remain open and no voltage is supplied to the Rear Blower Motor.

When the Ignition Switch is in RUN and the Rear Auxiliary Heater Control Switch is in LO, a ground path is provided for the Rear Low Blower Relay Coil through the DK BLU (1926) wire to the Control Switch, then through BLK (150) wire to Ground G200. The Relay Coil energizes and the relay contacts close. This applies Battery voltage to the Rear Blower Resistor through the YEL (1176) wire. Current flows through two resistors and to the Rear Blower Motor through the YEL (1172) wire. The motor operates at its slowest speed.

When the Rear Auxiliary Heater Control Switch is in MED. the Rear Medium Blower Relay is energized. Current flows to the motor through one resistor and the motor operates at an intermediate speed. When the Rear Auxiliary Heater Control Switch is in HI, the Rear High Blower Relay is energized. Current bypasses both resistors and the motor operates at its highest speed.

An illumination lamp is provided at the Rear Auxiliary Heater Control Switch to facilitate Switch operations. The lamp is powered by the Instrument Panel Dimming system described in Instrument Panel Dimming. Testing and Inspection