Ford 2003 Mustang Workshop Manual page 3045

The panel/defrost door vacuum control motor is at full vacuum and the panel/floor door vacuum
control motor is at no vacuum, directing airflow to the instrument panel A/C registers. A small
amount of airflow from the side window demisters will be present.
Blended air temperature is available.
The A/C compressor will operate if the outside air temperature is above approximately 6°C (43°
F).
The blower motor is on.
PANEL
When PANEL is selected:
The air inlet door vacuum control motor is at no vacuum, admitting only outside air into the
passenger compartment.
The panel/defrost door vacuum control motor is at full vacuum and the panel/floor door vacuum
control motor is at no vacuum, directing airflow to the instrument panel A/C registers. A small
amount of airflow from the side window demisters will be present.
The temperature can be adjusted to heat the air, but the air cannot be cooled below the outside
temperature.
The A/C compressor will not operate.
The blower motor is on.
OFF
When OFF is selected:
The air inlet door vacuum control motor is at full vacuum, closing off outside air from entering
the passenger compartment.
The panel/floor door vacuum control motor is at full vacuum and the panel/defrost door vacuum