HEATER Mode
WARNING: This page is about a different car, the 1998 Chevrolet Monte Carlo and 1998 Chevrolet Lumina. However, it is still accessible from the selected car via links, so may be relevant.
In this mode, compressor does not operate and outside air is heated and distributed. Approximately 80 percent of heated air goes to floor, and 20 percent goes to windshield (defrost) vents.