2008 GMC Envoy Owner's Manual - Page 157

Rear Window Defogger If your vehicle has the rear window defogger a warming grid is used to remove fog on the rear window. Dual Automatic Climate Control System < (Rear): Press this button to turn the rear window defogger on or off. An indicator light in the button will come on to let you know that the rear window defogger is active. The rear window defogger will automatically turn off approximately ten minutes after the button is pressed. If your vehicle has heated mirrors, this button will activate them. Notice: Do not use anything sharp on the inside of the rear window. If you do, you could cut or damage the warming grid, 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. With this system you can control the heating, cooling and ventilation for your vehicle. When your vehicle is first started and the climate control system is on, or if the climate control system has been turned on, the display will show the driver's temperature setting for five seconds. Then it will show the outside temperature. 3-23