GMC 2009 Sierra - Manual (Page 160)

Rear Window Defogger
If your vehicle has a rear window defogger it uses a
warming grid to remove fog from the rear window.
The rear window defogger will only work when
the ignition is in RUN.
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(Rear): Press this button to turn the rear window
defogger on or off. An indicator light on the button
will come on to let you know that the rear window
defogger is activated.
The rear window defogger will only work when the
ignition is in RUN. The rear window defogger will stay
on for approximately 10 minutes after the button is
pressed, unless the ignition is turned to ACC or LOCK.
The defogger can also be turned off by pressing the
button again or by turning off the engine.
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.
Climate Control System
(Heater Only)
With this system you can control the heating and
ventilation for your vehicle.
Operation
9
(Fan): Turn the left knob clockwise or
counterclockwise to increase or decrease the fan speed.
Turn the knob all the way counterclockwise to turn the
front system off.
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