Climate Control Assembly

CLIMATE CONTROL ASSEMBLY
The manual A/C-heater control includes the following features:

Airflow Control
^ A function selector knob which has positions: OFF, MAX-A/C, A/C, Panel, Panel/Floor, Floor, Floor/Defrost.
^ The position of the knob determines the manner in which the system will operate.
- A temperature control knob manually sets the desired comfort temperature.
- Fan control knob controls the volume of air movement.
^ Each position of the function selector knob and fan control knob is detented for positive engagement.
^ The fan control knob provides four manually-selected A/C blower motor speeds and may be operated in any position of the function selector knob except OFF to select the desired amount of airflow.

The A/C control assembly consists of three main parts:






1. The function selector knob, a vacuum selector valve combined with an internal electrical switch.
2. Heater blower motor switch, an electrical switch that provides four speeds of A/C blower motor operation.
3. A temperature control knob, which controls the position of the temperature blend door mounted on the A/C evaporator housing assembly.

The function selector actuates an eight-port air conditioner control that controls the vacuum control motor at the floor/defrost, panel/defrost, and outside/recirc. air doors. The function selector also controls the OFF-ON operation of the heater blower motor switch and activates the circuit for the A/C clutch circuit in the A/C position.

In either A/C position and in FLOOR/DEFROST and DEFROST positions, compressor operation is dependent upon the A/C cycling switch.

The cutout pressure is approximately 161 kPa (23 psi). Cut-in pressure is approximately 321 kPa (46 psi).

The following relates function and temperature lever settings for direction of airflow into the passenger compartment.

Function Lever

Lever Position Airflow Direction
Panel Instrument panel registers.

PNL/FLR Split between instrument panel registers and floor outlets.

Floor with bleed to defrosters.

FLR/DEF Split between floor outlets and defrosters.

Defrost Defroster with bleed to floor outlets.

Max A/C Instrument panel registers.

Temperature Lever

Lever Position Airflow Direction
Cool (Full) All air bypasses heater core.

Warm (Full) All air flows through heater core.

Between Cool and Warm Amount of air through heater core is proportionate to the amount that the blend air door is opened or closed to the extremes of cool or warm.

Temperature Control
The temperature selector actuates a variable resistance switch. This switch varies the voltage to an electric actuator used to position the temperature blend door.

Positioning the temperature control in any position between COOL and WARM causes the temperature blend door to direct more or less outside air through or around the heater core for whatever proportion of heated or unheated outside air is desired.

The air blends together as it leaves the heater core and enters the heater air plenum chamber for distribution.

VACUUM HOSES
An A/C plenum vacuum harness which is attached to the manual A/C control, directs vacuum to the different airflow doors within the heater air plenum chamber.

SYSTEM AIRFLOW DESCRIPTION
Air is drawn into the system by the blower motor through the outside-recirc. door opening. The air is blown through the A/C evaporator core and then the heater core (when the temperature control is moved toward the WARM position). When the temperature blend door is in the maximum cool position, the air bypasses the heater core. When the temperature control is moved to the right, away from the maximum cool position, air passes through the heater core where it is warmed, and then mixed with the cool air before it is discharged through the registers.

OFF
With the function selector in the OFF position, the outside-recirc. door is in the recirculated air position. It is closed to outside air and no air passes through the system. The blower motor is off.

MAX A/C

NOTE: No temperature modulation is possible in the MAX A/C position.

In the MAX A/C position, the outside-recirc. air door is in the recirculated air position. All of the air discharges through the panel registers except for a small amount of floor bleed. The A/C compressor operates in this function control setting.

PANEL/FLOOR
In the PANEL/FLOOR position, the outside/recirc. air door is open to outside air (no vacuum). Air is discharged through the heater outlet floor ducts and panel registers. The A/C compressor will engage in this mode if outside air temperatures are above approximately 10°C (50°F).

NORM A/C
In the NORM A/C position the outside-recirc. air door is open to the outside (no vacuum) and outside air is discharged through the panel register with a small amount of floor bleed. The A/C compressor operates in this control setting.

PANEL
In the PANEL position the outside-recirc. air door is open to the outside (no vacuum), and outside air is discharged through the panel registers except for a small amount of floor bleed. The A/C compressor does not operate in this control setting.

FLOOR
In the FLOOR position, the outside-recirc. air door is open to outside air (no vacuum). Air is discharged through the heater outlet floor ducts plus a small amount of bleed is directed to the windshield.

DEF/FLR
In the DEF/FLR position air is discharged through both the windshield defroster hose nozzle and heater outlet floor ducts in approximate equal amounts. The A/C compressor operates in this control setting when the A/C cycling switch is energized.

DEFROST
In the DEFROST position, the air is discharged through the windshield defroster hose nozzles. There is also a small amount of floor bleed. The A/C compressor operates in this control setting to help dehumidify the air.