GMC 2009 Sierra - Manual (Page 168)

Rear Window Defogger
The rear window defogger uses a warming grid to
remove fog from the rear window.
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(Rear Window Defogger): If your vehicle has this
feature, press this button to turn the defogger on or
off. It automatically turns off several minutes after it has
been activated. The defogger can also be turned off
by turning the engine off. Do not drive the vehicle until
all the windows are clear.
Notice: Do not use a razor blade or sharp object
to clear the inside rear window. Do not adhere
anything to the defogger grid lines in the rear glass.
These actions may damage the rear defogger.
Repairs would not be covered by your warranty.
Heated Mirrors: If your vehicle has 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. See Outside Power
Mirrors on page 2-39.
Outlet Adjustment
Use the air outlets located in the center and on the side
of the instrument panel to direct the airflow.
Operation Tips
• Clear away any ice, snow, or leaves from air inlets
at the base of the windshield that could block the
flow of air into your vehicle.
• Keep the path under the front seats clear of objects
to help circulate the air inside of the vehicle more
effectively.
• Use of non-GM approved hood deflectors can
adversely affect the performance of the system.
Check with your dealer/retailer before adding
equipment to the outside of your vehicle.
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