1998 Pontiac Firebird Owner's Manual - Page 150

Rear Window Defogger (If Equipped) Do not attach anything like a temporary vehicle license or a decal across the defogger grid the rear window. on 0 The rear window defogger uses a warming grid to remove fog from the rear window. NOTICE: Don't use a razor blade or something else sharp on the inside the rear window. you do, you of If could cutor damage the warming grid, and the repairs wouldn't be covered by your warranty. Press the button to on the defogger. An indicator turn light will come on to remind you that the defogger is on. The defogger will turnoff automatically after about 10 minutes of use. If you turn it on again, the defogger will operate about five minutes only. for You can turn the defogger off by pressing the button again. 3-5