System Operation

MAX A/C
When MAX A/C is selected:
- The recirculation air duct door vacuum control motor is at full vacuum, closing off outside air and recirculating passenger compartment air.
- The heater control valve is at full vacuum, preventing hot coolant from reaching the heater core.
- The floor/panel door vacuum control motor) is at no vacuum and the panel/defrost door vacuum control motor is at full vacuum, directing airflow to the instrument panel A/C registers. There is also some airflow to the side window demisters.
- Temperature control is usually set for maximum cold.
- The A/C compressor will be enabled when MAX A/C is selected.
- The blower motor is on.







A/C
When A/C is selected:
- The recirculation air duct door vacuum control motor is set at no vacuum, blocking the recirculation passage and admitting outside air.
- The heater control valve is at no vacuum, allowing hot coolant into the heater core.
- The floor/panel door vacuum control motor is at no vacuum and the panel/defrost door vacuum control motor is at full vacuum, directing airflow to the instrument panel A/C registers.
- The temperature setting can be adjusted to mix air flowing through and around the heater core to achieve the desired temperature.
- The A/C compressor will be enabled when A/C is selected.
- The blower motor is on.







VENT
When VENT is selected:
- The recirculation air duct door vacuum control motor is set at no vacuum, blocking the recirculation passage and admitting outside air.
- The heater control valve is at no vacuum, allowing hot coolant into the heater core.
- The floor/panel door vacuum control motor is at no vacuum and the panel/defrost door vacuum control motor is at full vacuum, directing airflow to the instrument panel A/C registers.
- The temperature setting can be adjusted to mix air flowing through and around the heater core to achieve the desired temperature but air cannot be cooled below outside temperature.
- The A/C compressor will be disabled when vent is selected.
- The blower motor is on.







OFF
When OFF is selected:
- The recirculation air duct door vacuum control motor is at full vacuum, closing off outside air and recirculating passenger compartment air.
- The heater control valve is at full vacuum, preventing hot coolant from reaching the heater core.
- The floor/panel door and panel/defrost door vacuum control motors are at full vacuum, closing off airflow to the instrument panel A/C registers.
- The blower motor and the A/C compressor are off.







PANEL/FLOOR
When PANEL/FLOOR is selected:
- The recirculation air duct door vacuum control motor is set at no vacuum, blocking the recirculation passage and admitting outside air.
- The heater control valve is also at no vacuum, allowing hot coolant into the heater core.
- The floor/panel door vacuum control motor is in the partial vacuum position and the panel/defrost door vacuum control motor is at full vacuum, allowing airflow to both the instrument panel A/C registers and the heater outlet floor duct. There is also some airflow to the side window demisters.
- The temperature setting can be adjusted to mix air flowing through and around the heater core to achieve the desired temperature.
- The A/C compressor will be enabled when panel/floor is selected.
- The blower motor is on.







FLOOR
When FLOOR is selected:
- The recirculation air duct door vacuum control motor is set at no vacuum, blocking the recirculation passage and admitting outside air.
- The heater control valve is at no vacuum, allowing hot coolant into the heater core.
- The floor/panel door vacuum control motor is in the full vacuum position and the panel/defrost door vacuum control motor is in the no vacuum position, directing airflow to the heater outlet floor duct. There is also some airflow to the side window demisters.
- The temperature setting can be adjusted to mix air flowing through and around the heater core to achieve the desired temperature but air cannot be cooled below outside temperature.
- The A/C compressor will be disabled when floor is selected.
- The blower motor is on.







FLOOR/DEFROST
When FLOOR/DEFROST is selected:
- The recirculation air duct door vacuum control motor is set at no vacuum blocking the recirculation passage and admitting outside air.
- The heater control valve is at no vacuum, allowing hot coolant into the heater core.
- The floor/panel door vacuum control motor is in the partial vacuum position and the panel/defrost door vacuum control motor is in the no vacuum position, allowing airflow to both the windshield defroster hose nozzle and the heater outlet floor duct. There is also some airflow to the side window demisters.
- The temperature setting can be adjusted to mix air flowing through and around the heater core to achieve the desired temperature.
- The A/C compressor will be enabled when floor/defrost is selected to dehumidify the air and reduce windshield fogging.
- The blower motor is on.







DEFROST
When DEFROST is selected:
- The recirculation air duct door vacuum control motor is set at no vacuum, blocking the recirculation passage and admitting outside air.
- The heater control valve is at no vacuum, allowing hot coolant into the heater core.
- The floor/panel door and panel/defrost door vacuum control motors are in the no vacuum position so that most of the incoming air is directed to the windshield defroster hose nozzle. There is also airflow to the side window demisters.
- The temperature setting can be adjusted to mix air flowing through and around the heater core to achieve the desired temperature.
- The A/C compressor will be enabled when defrost is selected to dehumidify the air and reduce windshield fogging.
- The blower motor is on.

Manual A/C Electrical Components, Part 1:

Manual A/C Electrical Components, Part 2:

Manual A/C