The air inlet duct door is at full vacuum, closing off outside air and admitting only recirculated air.
The panel vent airflow door and the defrost/floor airflow door are at full vacuum, directing airflow to the A/C registers.
Temperature control is usually set for maximum cold but may be heated if selected.
Air will be picked up at the recirc opening by the blower motor. With the temperature control set for maximum cold, airflow across the A/C evaporator core will be diverted past the heater core and then directed into the passenger compartment through the instrument panel A/C registers.
The A/C compressor will be enabled when MAX A/C is selected.
The air inlet duct door is in the no vacuum position, admitting outside air.
Both the panel vent airflow door and the defrost/floor airflow door 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 demister and hose.
The temperature control knob setting will determine the amount of air that is directed through the heater core and the amount that bypasses the heater core.
The A/C compressor will be enabled when DEFROST is selected to dehumidify the air and reduce windshield fogging.