2011 Chevrolet Impala Owner's Manual - Page 206

8-4 Climate Controls Rear Window Defogger The rear window defogger uses a warming grid to remove fog from the rear window. For vehicles with heated outside rearview mirrors, the mirrors heat to help clear fog or frost from the surface of the mirror when the rear window defog button is pressed. See Power Mirrors on page 2‑14. Do not drive the vehicle until all the windows are clear. 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 the vehicle warranty. Do not attach a temporary vehicle license, tape, a decal, or anything similar to the defogger grid. : (Outside Air): Press to turn on outside air. An indicator light comes on to show that it is on. Outside air will circulate throughout the vehicle. ? (Recirculation): Press to turn on the recirculation mode. An indicator light comes on to show that it is on. This mode helps to quickly heat or cool the air inside the vehicle once the temperature inside the vehicle is equal to or better than the outside temperature. It can be used to prevent outside air and odors from entering the vehicle. The recirculation mode is not available in outside air, floor, defog, or defrost modes. If the button is selected while in these modes, the indicator flashes three times. < (Rear Window Defogger): The rear window defogger turns off automatically after it has been activated for 10 minutes. It can be turned off manually, by pressing the button again or by turning the ignition to the LOCK/OFF position. The rear window defogger can be turned on again for additional window clearing. The length of defogger operation will increase if the vehicle is being driven.