2003 GMC Safari Owner's Manual - Page 146

Be sure to keep the area under the front seats clear of any objects so that the air inside of your vehicle can circulate effectively. For information on how to use the main climate-control system. For information on ventilation, see "Outlet Adjustment" listed later in this section. Press this button to turn the rear window defogger on or off. Be sure to Rear Climate Control System Rear Window Defogger Your vehicle may have a rear window defogger that uses a warming grid to remove fog or frost from the rear window. The rear window defogger will only work when the ignition is in RUN. The rear window defogger will turn off several minutes after the button is pressed. If turned on again, the defogger will run for several more minutes before turning off. The defogger can also be turned off by pressing the button again or by turning off the engine. Notice: Don't use a razor blade or something else sharp on the inside the rear window. If you do, of you could cut or damage the defogger and the repairs would not be covered by your warranty. Do not attach a temporary vehicle license, tape, a decal or anything similar to the defogger grid. 3-2 1