2001 GMC Savana Van Owner's Manual - Page 151

Heating On cold days, use HEAT with the temperature knob in the red area. Outside air will be brought in through the floor outlets. The heater works best if you keep your windows closed while using it. If you use the optional engine coolant heater before starting your engine, your heating system will produce warmer air faster to heat the passenger compartment in cold weather. See "Engine Coolant Heater" in the Index. To turn on the rear window defogger, press this button located near the fan control. An indicator light in the button will come on when the rear window defogger is working. Defrosting Use DEFROST to remove fog or ice from the windshield quickly in extremely cold conditions. The temperature knob should be in the red area and the fan knob toward high. The air conditioning compressor may operate in this setting to dehumidify the air. The rear window defogger will only work when the ignition is in RUN. The rear window defogger will turn itself off after several minutes. If you need additional warming time, press the button again. Pressing the button when the indicator light is illuminated will turn the defogger off. If your vehicle is equipped with heated outside rearview mirrors, the rear window defogger button will activate both the rear window defogger and the heated outside rearview mirrors. See "Heated Outside Rearview Mirrors" in the Index. Rear Window Defogger (If Equipped) If you see lines running across the rear windows, you have a rear window defogger. The lines warm the glass. For best results, clear the windows of as much snow or ice as possible before using the rear window defogger. 3-7