2002 Chevrolet Astro Owner's Manual - Page 156

Rear Window Defogger (Option) If your vehicle has this option, the rear window will have lines running across the glass. These lines heat your window. For best results, clear the window of as much snow or ice as possible before using the rear window defogger. To turn on the rear window defogger, find the button located to the left of the heater controls with the defog symbol on it. The rear window defogger will only work when the ignition is in RUN. You can turn the defogger off at any time by pressing the button again. The defogger will shut itself off after several minutes so that the glass does not get too hot. If the window still isn't clear, turn the defogger on again. Do not attach a temporary vehicle license, tape or decals across the defogger grid on the rear window. NOTICE: Don't use a razor blade or something else sharp on the inside of the rear window. If you do, you could cut or damage the defogger and the repairs would not be covered by your warranty. Press the button until the light comes on, then release it. 3-7