GMC 2007 Acadia Owner's Manual page 178

Heated Windshield Washer
If your vehicle has the heated windshield washer
fluid system it can be used to help clear ice,
snow, tree sap, or bugs from the windshield. This
feature only works with the front wiper system,
not the rear wiper system.
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The button is located
to the left of the
steering column on
the instrument panel.
Push the heated washer fluid button to activate
the heated windshield washer fluid system.
This activation begins four heated wash/wipe
cycles. The first heated wash/wipe cycle can
take up to 40 seconds to occur, depending
on outside temperature. After the first wash/wipe
cycle, it can take up to 20 seconds for each of
the remaining cycles. Press the button again
to turn off the heated windshield washer fluid
system or it will automatically turn off after
four wipe cycles have been completed.
When the heated windshield washer fluid system
is activated under certain outside temperature
conditions, steam might flow out of the washer
nozzles for a short period of time before washer
fluid is sprayed. This is a normal condition.
WASHER FLUID LOW ADD FLUID is displayed
on the DIC when the washer fluid is low. See
DIC Warnings and Messages on page 244.