General Description

NOTICE: The refrigeration system on this vehicle uses R-134a which is not compatible with refrigerant R-12. Before servicing the system always make sure the proper servicing equipment is used or the system could become severely damaged. Always refer to the service text and manufacturer instructions included with service equipment before proceeding.

The air conditioning system delivers air that has been heated or cooled and dehumidified for occupant comfort. It also provides power ventilation, windshield defrosting and side window defogging.
During most operating conditions, outside air is drawn through the heater and air conditioning module assembly by the blower motor. Additional outside air is also forced into the vehicle by forward movement of the vehicle.

Within the evaporator module, air is pushed by the blower motor through the evaporator, through the heater core, then into the passenger compartment. For air conditioning or defroster operation at ambient temperatures above 6°C (43°F), the refrigeration system will chill the evaporator to almost freezing. As the air passes through the evaporator, the air temperature drops which causes the moisture in the air to condense on the evaporator core fins. This moisture leaves the vehicle by gravity feed through a drain hole, dehumidifying the vehicle.

From the evaporator, some or all of the air may pass through the heater core, which is warmed by engine coolant. Any of the air which is not to be heated will mix with the heated air before entering the passenger compartment.

When maximum air conditioning mode is selected, most of the air entering the blower motor is taken from the passenger compartment (recirculated) where it is most likely to be cooler than the outside air. Only outside air is used in all other modes.

REAR A/C SYSTEM (C69)

The rear A/C system operates with the front system. It does not operate independently. However, control of the rear blower motor speed is possible when the front system is oft. Rear air circulation without the refrigerant function is possible by operating the rear blower control switch.

These units operate on inside (recirculated) air. Air enters the unit and passes through the evaporator core into the passenger compartment through the air distributor duct. The front system controls the rear system. A three-speed blower switch controls the rear overhead system.