Rear Heater - Without A/C

The Blower Motor delivers air to the interior of the vehicle. Its speed is controlled by the Blower Switch and the Blower Resistors. When the Ignition Switch is in RUN Battery Voltage is supplied to the Blower Switch. With the Blower Switch in LO. voltage is supplied across all three Blower Resistors and the Blower Motor. The Blower Motor runs at its slowest speed. With the Blower Switch in MED1, one of the three Blower Resistors is bypassed and the Blower Motor runs faster. With the Blower Switch in MED2, two of the three Blower Resistors are bypassed and the Blower Motor runs faster yet. When the Blower Switch is set to HI. Battery Voltage is supplied directly to the Blower Motor and the Blower Motor runs at its fastest speed.

REAR HEATER
The Rear Heater Controlled by the Rear Heater Switch Battery Voltage is provided to the Rear Heater and A/C Relay by HTR-A/C (Fuse 12) and BRN (141) wire. The Coil of this Relay is grounded by BLK (850) wire and it is energized when the Ignition Switch is in the RUN position. When the relay is energized it provides Battery Voltage to the Rear Heater Switch. Fuse M2 (RR HEAT/A/C) provides Battery Voltage to RED (742) wire and the common contact of the Rear Heat-AC Relay. When the relay is energized. the common contact and the normally open contact are connected which then provides power to the ORN (923) wire which supplies the Rear Heater Switch.

HI SPEED
Blower Speed Control is accomplished by the Rear Heater Switch, for the Rear Heater Blower Motor. The ORN 1923 wire provides Battery Voltage to the Rotary contact of the Switch. When the Switch is in the HIGH position, full Battery Voltage is provided to the Rear Heater Blower Motor through the WHT (1924) wire. The Rear Heater Blower Motor is grounded through the BLK(1150) wire and it will operate at full speed.

LO/MED SPEEDS
Slower Blower Motor speeds are accomplished by limiting the current flow through the Rear Heater Blower Motor. This is accomplished by placing resistance in the current path for the Motor. When the MEDIUM setting is selected, a current path is provided through Terminal A of the Rear Heater Resistor Pack RED (1925) wire and through the Resistor connected to Terminal B of the Rear Heater Resistor Pack and on out through to the Rear Heater Blower Motor. This Circuit puts one Resistor in the current path. When an even lower speed is desired, the Blower Switch is placed in the LOW position. This provides a current path Through the Switch to Terminal C of the Rear Heater Resistor Pack DK BLU (1926) wire. The Circuit is then completed through the resistor connected to Terminal C and the resistor connected to Terminal B. This places two Resistors in the Motor current path, thus reducing Motor current even further. Power is completely removed from the motor if the Switch is placed in the OFF position.

Heated Engine Coolant is provided to the Rear Heater Core when the Heater A/C Control Valve Solenoid is energized. This solenoid is powered by a second set of contacts in the Rear Heater Switch. Battery Voltage from ORN (1923) wire is provided through the switch positions HIGH, MEDIUM, and LOW. Battery Voltage is provided, in these positions, to GRY/BLK (1596) wire, C209 Terminal D, through the Convenience Center to C100 Terminal D1 and finally to the A Terminal of the Heater and A/C Control Valve Solenoid. The Solenoid is grounded at Terminal B by BLK (850) wire and will be energized. Power is not provided to the Solenoid in the OFF Switch position.