Function Control Knob
Function control knob can be placed in OFF, panel, panel/floor, floor, floor/defrost or defrost position. Function control knob operates a vacuum switch connected to appropriate actuator motors, which operate floor/defrost and panel doors.
Outside/recirculation door is controlled by a vacuum valve and vacuum motor. When function control knob is in OFF position, vacuum is applied to outside/recirculation door vacuum motor to shut off outside airflow. When function control knob is in any other position, vacuum is not applied to outside/recirculation door vacuum motor and outside air is allowed to enter vehicle.
When function control is in panel position, air inlet door vacuum control motor is at no vacuum, admitting only outside air into passenger compartment. See Fig 1. Panel/defrost door vacuum control motor is at full vacuum and panel/floor door vacuum control motor is at no vacuum, directing airflow to instrument panel registers. A small amount of airflow from side window demisters will be present. Heater control valve is at no vacuum, allowing flow of hot coolant to heater core. Blended air temperature is available. Temperature can be adjusted to heat air. Blower motor is on.
When function control is in off position, air inlet door vacuum control motor is at full vacuum, closing off outside air from entering passenger compartment. See Fig 2. Panel/floor door vacuum control motor is at full vacuum and panel/defrost door vacuum control motor is at no vacuum, closing off airflow to defrost duct, side window demisters, floor duct and instrument panel registers. A small amount of airflow from side window demisters will be present. Heater control valve is at full vacuum, preventing flow of hot coolant to heater core. Blower motor is off.
When function control is in panel/floor position, air inlet door vacuum control motor is at no vacuum, admitting only outside air into passenger compartment. See Fig 3. Panel/defrost door vacuum control motor is at full vacuum and panel/floor door vacuum control motor is at partial vacuum, directing airflow to floor duct and instrument panel registers. A small amount of airflow from side window demisters will be present. Heater control valve is at no vacuum, allowing flow of hot coolant to heater core. Blended air temperature is available. Blower motor is on.
When function control is in floor position, air inlet door vacuum control motor is at no vacuum, admitting only outside air into passenger compartment. See Fig 4. Panel/floor door vacuum control motor is at full vacuum and panel/defrost door vacuum control motor is at no vacuum, directing airflow to floor duct. A small amount of airflow from side window demisters will be present. Heater control valve is at no vacuum, allowing flow of hot coolant to heater core. Blended air temperature is available. Temperature can be adjusted to heat air. Blower motor is on.
When function control is in floor/defrost position, air inlet door vacuum control motor is at no vacuum, admitting only outside air into passenger compartment. See Fig 5. Panel/floor door vacuum control motor is at partial vacuum and panel/defrost door vacuum control motor is at no vacuum, directing airflow to floor duct, defroster duct and side window demisters. A small amount of airflow from side window demisters will be present. Heater control valve is at no vacuum allowing flow of hot coolant to heater core. Blended air temperature is available. Temperature can be adjusted to heat air. Blower motor is on.
When function control is in defrost position, air inlet door vacuum control motor is at no vacuum, admitting only outside air into passenger compartment. See Fig 6. Panel/floor door and panel/defrost door vacuum control motors are at no vacuum, directing airflow to defroster duct and side window demisters. A small amount of airflow from side window demisters will be present. Heater control valve is at no vacuum allowing flow of hot coolant to heater core. Blended air temperature is available. Temperature can be adjusted to heat air. Blower motor is on.