Buick 2009 Lucerne - Manual (Page 171)

Rear Window Defogger
The rear window defogger uses a warming grid to
remove fog or frost from the rear window.
< (Rear Defogger): Press to turn the rear window
defogger on or off. An indicator light below the button
comes on to show that the rear window defogger is on.
Be sure to clear as much snow from the rear window
as possible.
The rear window defogger only works when the ignition
is in ON/RUN. The rear window defogger stays on
for about 20 minutes after the button is pressed if the
vehicle is traveling at slower vehicle speeds. At higher
vehicle speeds the rear window defogger may stay
on continuously. If turned on again, the defogger
only runs for about 10 minutes before turning off.
The defogger can be turned off by pressing the button
again, by turning the ignition to ACC/ACCESSORY
or ON/RUN, or by turning off the engine.
The heated outside rearview mirrors will heat to help
clear fog or frost from the surface of the mirror when
the rear window defogger is on. See Outside Heated
Mirrors on page 2-37 for more information.
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.
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