System Airflow Description - Dual Automatic Temperature Control: Defrost

WARNING: This page is about a different car, the 2003 Lincoln Aviator. However, it is still accessible from the selected car via links, so may be relevant.

When DEFROST is selected:

The RECIRC button is disabled. The recirculation door vacuum control motor is at no vacuum, admitting only outside air into the passenger compartment.
The floor door, defrost door and panel door vacuum control motors are at no vacuum, directing airflow to the defroster duct and side window demisters. A small amount of airflow from the instrument panel A/C registers and the floor duct will be present.
The heater control valve is automatically controlled by the DATC module based on the temperature settings.
Temperature control can be adjusted by directing the airflow through and around the heater core.
The A/C request switch will be disabled and will not illuminate. The A/C compressor will operate automatically if the outside air temperature is above approximately 4°C (39.5°F).
The blower motor is on.