Rear Heater & A/C Controls

The Rear Heater and, A/C functions are controlled by the Rear Heater Switch and the Rear A/C Switch respectively. Battery voltage provided to the Rear Heater-A/C Relay (Rear) coil by HTR-A/C Fuse 12 and the BRN (141) wire. The Coil is grounded by the BLK (850) wire cavity B9 of the Rear Heater A/C Relay (Rear). The Rear Heater A/C Relay (Rear) is energized when the Ignition Switch is in the RUN position. It provides battery voltage to both the Rear Heater Switch and the Rear A/C Switch. The RR HEAT/A/C MAXI Fuse M2 provides battery voltage to the RED (742) wire cavity A9 which is the common contact of the Rear Heater A/C Relay (Rear). When the Relay is energized the common contact and the normally open contact are connected which then provides voltage to the ORN (1923) wire cavity B7 of the Rear Heat A/C Relay (Rear) which supplies the Rear Heater and Rear A/C switches. The Blower speeds are controlled by the Rear Heater Switch, for the Rear Heater Blower Motor and the Rear A/C Switch for the Rear A/C Blower Motor The ORN (1923) wire provides battery voltage to the rotary contact of both switches. When either switch is in the HIGH position, full current flow is provided to the Blower Motor via the WHT (1924) wire (for Rear Heater), OR (1052) wire (for Rear A/C). The Motor is grounded through BLK (1150) wire and BLK (1250) respectively and it will operate at full speed.

Slower Blower speeds are accomplished by limiting the current (low through the two above mentioned Blower Motors. This is accomplished by placing resistance in the current path for the Rear Blower Motor. When the MEDIUM setting is selected, a current path is provided through RED (1925) cavity A of the Rear Heater Resistor Pack for Heater, LT BLU ( 1072) wire cavity A For A/C and through the Rear AC Resistor Pack connected through the respective Motor This cavity 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 DK BLU(1926) wire (Heater), YEL (1176) wire (A/C and on to cavity C of the Resistor Pack, the cavity is then completed through the resistor connected to cavity C and the resistor connected to cavity B. This places two resistors in the current path, thus reducing current to the Motor even more.

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) is provided through the Switch positions HIGH, MEDIUM and LOW. Battery voltage is provided, in these positions, to GRY/BLK (1596) wire, through the Convenience Center to the Heater A/C Control Valve Solenoid. The solenoid is grounded at BLK (850) and will be energized.