Function Selector Switch
WARNING: This page is about a different car, the 2006 Mercury Mariner and 2006 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
The function selector switch combines a vacuum selector valve that determines air distribution and an electrical switch to supply battery voltage to the A/C compressor circuit and the blower motor circuit. When the function selector switch is in the MAX A/C, A/C, FLOOR/DEFROST or DEFROST positions, the A/C compressor will be operational. The function selector switch can be replaced separately from the climate control head unit.