1997 Oldsmobile Achieva Owner's Manual - Page 135

Rear Window Defogger The rear window defogger uses a warming grid to remove fog from the rear window. Do not attach a temporary vehicle license 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 warming grid, and the repairs wouldn't be covered by your warranty. Ventilation System Press the defogger switch. The indicator light glow. will If your vehicle is traveling under 45 mph (70 km/h), the rear window defogger will turn off automatically after about 10 minutes of use. If your vehicle is traveling over 45 mph (70 km/h), the defogger will operate continuously. You can turn the defoggeroff by turning off the ignition or pressing the switch again. Your Oldsmobile's flow-through ventilation system supplies outside air into the vehicle when it is moving. Outside airwill also enter the vehicle when the fan is running.