Mode Selector Switch
WARNING: This page is about a different car, the 2002 GMC Safari and 2002 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.
Mode selector switch controls a rotary vacuum switch, which routes vacuum to specific vacuum actuators to operate air door motors, providing desired air distribution. It also allows for selection of A/C or heating functions, including defrost. Mode knob positions are OFF, MAX A/C, A/C, BI-LEVEL, VENT, FOOT, FOOT-DEFROST and DEF (DEFROST).