Without Air Conditioning

REAR AUXILIARY HEATER
The Rear Auxiliary Heater Module operates independently from the vehicle front heater except that both systems receive their hot water supply from the engine cooling system.

LO OPERATION
When the Ignition Switch is in the RUN position, voltage is applied through RR HVAC FUSE to the coil (power side) of the Low Blower Relay. When the Rear Auxiliary Heater Control Switch is turned to the "LO" position, ground is supplied from G200 through the closed contacts of the Rear Auxiliary Heater Control Switch to the coil (ground side) of the Low Blower Relay. With both power and ground applied to the coil of the Low Blower Relay, it energizes and its contacts close. Voltage is applied through the MAXI FUSE and the closed contacts of the Low Blower Relay to the Blower Resistor. Voltage is applied across both of the resistors in the Blower Resistor, thus lowering the voltage potential at the Rear Blower Motor. Since the Rear Blower Motor is grounded at G400, it will operate at approximately one third of full speed operation.

MEDIUM OPERATION
When the Ignition Switch is in the RUN position, voltage is applied through RR HVAC FUSE to the coil (power side) of the Medium Blower Relay. When the Rear Auxiliary Heater Control Switch is turned to the "MED" position, ground is supplied from G200 through the closed contacts of the Rear Auxiliary Heater Control Switch to the coil (ground side) of the Medium Blower Relay. With both power and ground applied to the coil of the Medium Blower Relay, it energizes and its contacts close. Voltage is applied through the A/C MAXI FUSE and the closed contacts of the Medium Blower Relay to the Blower Resistor. Voltage is applied across one of the resistors in the Blower Resistor to the Rear Blower Motor. Since a lesser amount of voltage is lost at the Blower Resistor, the voltage potential at the Rear Blower Motor is higher than that of the low speed operation. Therefore, the Rear Blower Motor will operate at approximately two thirds of full speed operation.

HI OPERATION
When the Ignition Switch is in the RUN position, voltage is applied through RR HVAC FUSE to the coil (power side) of the High Blower Relay. When the Rear Auxiliary Heater Control Switch is turned to the "HI" position, ground is supplied from G200 through the closed contacts of the Rear Auxiliary Heater Control Switch to the coil (ground side) of the High Blower Relay. With both power and ground applied to the coil of the High Blower Relay, it energizes and its contacts close. Voltage is applied through the MAXI FUSE and the closed contacts of the High Blower Relay to the Rear Blower Motor. Full system voltage is applied to the Rear Blower Motor. Since the Rear Blower Motor is grounded at G400, the Rear Blower Motor will operate at full speed.