Air Conditioning System

The manual A/C-heater system is a fixed orifice tube cycling clutch-type system using a suction accumulator/drier. A multi-pass, S-flow evaporator core is used.

The two service access gauge port valves are Schrader-type valves. The high-pressure valve is located in the discharge line near the compressor and requires a special adapter when connecting a manifold gauge set to the valve. The low-pressure valve is located in the suction line.

The refrigerant system uses four- or six-cylinder compressors for all engine applications.

System airflow is controlled by a six-port vacuum selector valve which is integral with the control assembly. System air temperature is regulated by a temperature blend door operated by a self-adjusting cable.

The blower motor electrical circuit uses ground side switching which has the blower switch and the resistor assembly on the ground side of the motor instead of the battery side. This protects the resistor assembly from overheating in the event of an electrical short.

During system operation, air is drawn directly into the system by the blower motor and wheel from the cowl air intake in all function selector knob settings except OFF and MAX A/C. In the MAX A/C position, airflow is from inside the vehicle through the recirc duct. The air is then forced by the blower through the evaporator core and, depending on the setting of the temperature knob, through and/or around the heater core into the plenum. Air is then directed to the floor, defroster nozzles, demisters or the instrument panel registers depending on the position of the function selector knob.

A/C-Heater System Air Distribution

Airflow volume through the system is controlled by a four-position blower (FAN) switch. The blower (FAN) switch, used in conjunction with the resistor assembly, provides four blower speeds to control airflow through the A/C-heater assembly.

The A/C-heater system airflow schematic and vacuum control chart are shown in the following illustrations. These charts show the possible airflow routes and door positions. The vacuum control chart gives the vacuum applications for the different positions of the function and temperature selector knobs.

System Airflow Schematic (MAX, A/C, FLOOR)






System Airflow Schematic—(VENT, MIX DEFROST)






A/C-Heater System Vacuum Control Chart