2010 Chevrolet Suburban 2500 Owner's Manual - Page 240

The recirculation mode cannot be used with floor, defrost, or defogging modes. If recirculation is selected while in one of those modes, the indicator flashes three times and turns off. The air conditioning compressor will also come on when this mode is activated. While in recirculation mode the windows may fog when the weather is cold and damp. To clear the fog, select either the defog or defrost mode and increase the fan speed. The recirculation mode can also be turned off by turning off the engine. REAR: Press to turn the rear heating and air conditioning on. See Rear Air Conditioning and Heating System on page 4‑27 or Rear Air Conditioning and Heating System and Electronic Climate Controls on page 4‑28 for more information. Rear Window Defogger The rear window defogger uses a warming grid to remove fog from the rear window. < (Rear Window Defogger): Press this button to turn the rear window defogger on or off. The system automatically turns off several minutes after it has been activated. The defogger can also be turned off by turning off the engine. Do not drive the vehicle until all the windows are clear. For vehicles with heated outside rearview mirrors, the mirrors will heat to help clear fog or frost from the surface of the mirror when the rear window defog button is pressed. 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. 4-20