Blower speed control is accomplished by the rear heater switch for the rear heater blower motor. CKT 1923 (ORN) provides the battery voltage to the rotary contact of the switch. Full battery voltage is provided to the rear heater blower motor when the rear heater switch is in the HIGH position. The full battery voltage is provided to the rear heater blower motor through CKT 1924 (WHT). The rear heater blower motor is grounded through CKT 1150 (BLK). The rear heater blower motor will operate at full speed when grounded.

Limiting the current flow through the rear heater blower motor will accomplish slower blower motor speeds. Place resistance in the current path for the rear heater blower motor in order to accomplish the slower speeds. A current path is provided through, in the following order, when the MEDIUM setting is selected:

1. Terminal A of the rear heater resistor pack CKT 1925 (RED)
2. The resistor connected to terminal B of the rear heater resistor pack
3. The rear heater blower motor.

This circuit puts one resistor in the current path.

Place the blower motor in the LOW position in order to attain a lower speed. The lower speed provides a current path through the blower switch to terminal C of the rear heater resistor pack CKT 1926 (DK BLU). The circuit then competes through the resistor that is connected to terminal C and the resistor that is connected to terminal B. The complete circuit places 2 resistors in the rear heater blower motor current path. The 2 resistors reduce the rear heater blower motor current. Placing the blower switch into the OFF position completely removes power from the motor.

Energizing the A/C control valve solenoid provides heated engine coolant to the rear heater core. Power is provided to the solenoid by a second set of contacts in the rear heater switch. Battery voltage is provided through the switch positions HIGH, MEDIUM, and LOW from CKT 1923 (ORN). The HIGH, MEDIUM and LOW switch positions provide battery voltage through to following path:

1. CKT 1597 (GRY/BLK)
2. C219 terminal D
3. The convenience center
4. C100 terminal D1
5. Terminal A of the heater and A/C control valve solenoid.

The heater A/C control valve solenoid is grounded at terminal B by CKT 850 (BLK). The heater A/C control valve solenoid is energized when grounded. Power is not provided to the heater A/C control valve solenoid is in the OFF position.