A/C System - Manual

DESCRIPTION
The A/C-Heater system consists of the Control Assembly, Blower Housing, Evaporator Assembly, Compressor, Condenser and the necessary refrigerant hoses/lines to connect the refrigerant system components together. The Control Assembly contains the Function Selector Switch and Vacuum Valve, the Temperature Control Lever, and the blower speed switches for the front and the optional rear blower system.

OPERATION

The Function Selector Switch and Vacuum Valve - controls the vacuum function of the system air doors operation and the blower and the A/C clutch ON/OFF switches. The Temperature Control Lever moves a control cable connected to the temperature blend door, which directs air through and around the heater core to obtain the desired air temperature. A four position blower switch is used for the front system and a five position switch is used for the optional rear system.

When the Ignition Switch is in "RUN" and the Function Selector Switch is set in any position except "OFF", power is applied to the [1][2]Blower Motor Relay and the Auxiliary Blower Motor Relay coils. The relay coils energize, closing the relay contacts and completing the circuit for the blower motor operation. The speed of each motor depends on the position of the respective blower switch.

Electrical power is also supplied through the Function Selector Switch to the A/C clutch circuit when the Ignition Switch is in "RUN" and the Function Selector Switch is in "A/C-MAX", "A/C-NORM", "MIX" or "DEFROST". When the refrigerant system pressure drops to approximately 20 to 26 psi, the pressure switch will open and stop A/C compressor operation. As the refrigerant pressure rises, the cycle repeats itself to prevent icing of the evaporator core.

The Auxiliary Heater/AC System - uses two blower switches to control the Rear AC/Heater System. By setting the AC/Heater Auxiliary Blower Switch to the "Rear-Control" position, the Auxiliary Blower Motor can be controlled from the Rear Auxiliary Blower Switch, and operated at "MED-LO", "MED-HI", or "HIGH" speeds.


FUNCTION SELECTOR LEVER POSITIONS AND OPERATION

Off
Vacuum is applied to the Outside-Recirc. and Floor-Defrost door vacuum motors. The Outside-Recirc. door is closed to outside air, the Panel-Defrost door is open to defrost, and Floor-Defrost door is closed to defrost. The blower is off, and no air passes through the system.

Max A/C
Vacuum is applied to all vacuum motors. The Outside-Recirc. door is closed to outside air and opened to recirculate (in car) air. The Panel-Defrost and Floor-Defrost doors are closed to defrost, and discharge air flows from the instrument panel registers. The A/C compressor circuit is energized for A/C operation.

Norm A/C
Vacuum is applied to the Floor-Defrost and the Panel-Defrost door vacuum motors closing the doors to the defroster. The Outside-Recirc. door is opened to the outside air, and cooled outside air is discharged through the instrument panel registers. A/C compressor circuit is energized.

Vent
Air flow is the same as "NORM-A/C", except the air cannot be cooled because the compressor does not operate.

Floor
Vacuum is applied to both ports of the Floor-Defrost door. The Panel Defrost door is closed to the panel registers and outside air is directed to the floor outlets.

Mix
Vacuum is applied only to the rear port of the Floor-Defrost vacuum motor causing outside air flow to be split between the floor and defroster outlets. The A/C clutch circuit is energized for compressor operation to dehumidify the discharge air, providing the ambient temperature is above approximately 50° F.

Defrost
No vacuum is applied to the vacuum motors in the "DEFROST" position. Outside air flows past the Panel-Defrost door to the Floor-Defrost door where it is directed to the defroster outlets. The A/C clutch circuit is energized for compressor operation to dehumidify the discharge air providing the ambient temperature is above approximately 50° F.