A/C System - Manual

The Air Conditioner/Heater System contains a Function Selector Switch and Vacuum Valve, a temperature Control Lever (on the instrument panel), a blower housing assembly, an evaporator assembly and ductwork (behind the instrument panel), and Compressor and Condenser (in the engine compartment).

The Function Selector Switch and Vacuum Valve operate together to control system vacuum and electrical operation. Vacuum motors operate doors to direct air flow. The Function Selector Switch connects power to the Blower Motor and to the A/C Clutch Field Coil circuit.

The A/C Clutch Cycling Pressure Switch cuts off power to the A/C Clutch Field Coil when there is low refrigerant pressure.

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.

With the Ignition Switch in RUN and the Function Selector Switch in any position except OFF, voltage is applied to the Blower Motor.

The Speed of the Blower Motor id regulated by the Blower Switch and Blower Motor Resistor. With the front Blower Switch in LO, current flows through the Blower Motor and three resistors. In MED-LO, current flows through one resistor. In HI, current does not flow through any resistor. With the Function Selector Switch in OFF, the Blower Motor does not run.

With the Ignition Switch in RUN and the Function Selector Switch in MAX, NORM (A/C), FLR/DEF or DEFROST, the A/C Clutch Field Coil is activated, and the Compressor starts.

Lever Position and Operation

OFF

Vacuum is applied to the Outside Recirculate Door Vacuum Motor, closing that door on outside air. The Panel Door closes the instrument panel outlets. The Floor-Defrost Door opens the floor outlets. The Blower does not operate and air does not pass through the system.

A/C MAX

The Outside Recirculate Door Closes to outside air. The Panel Door sends air to the instrument panel outlets (vacuum on motor). With the Temperature Control Lever in the Cool position, the Temperature Blend Door prevents air flow through the Heater Core.

A/C NORM

Outside air comes through the Outside Recirculate Door. The Panel Door sends air to the instrument panel outlets (vacuum on motor). The Temperature Blend Door controls the air through the Heater Core.

VENT

Air flow is the same as i A/C NORM. The compressor is OFF.

FLOOR

Outside air, controlled by the Temperature Control Lever, is passed through or around the Heater Core. The Panel Door is closed and air is sent to the floor outlets (vacuum at ports A and B of the Floor-Defrost Door Vacuum Motor). The compressor is OFF.

FLR-DEF

The Outside-Recirculate Door lets in outside air (no vacuum at motor). Vacuum is applied at port A of the Floor-Defrost Door. The door moves to mid-position and air is split between the floor and defrost outlets. The Panel Door closes and the A/C compressor opeates to dehumidify the air.

DEFROST

With no vacuum at any Vacuum Motor, air passes through the outlets. The compressor operates to dehumidify the air.