GMC 2010 Yukon/Yukon XL Owner's Manual page 241

The defog mode is used to clear the
windows of fog or moisture. Air is directed to the
windshield, floor outlets, and side window vents. In this
mode, the system turns off recirculation and runs the air
conditioning compressor unless the outside temperature
is close to freezing. The recirculation mode cannot be
selected while in the defog mode.
The defrost mode is used to remove fog
or frost from the windshield more quickly. Air is directed
to the windshield and side window vents, with some
directed to the floor vents. In this mode, the system
automatically forces outside air into the vehicle.
The recirculation mode cannot be selected while in
the defrost mode. The air conditioning compressor
runs automatically in this setting, unless the outside
temperature is close to freezing.
Do not drive the vehicle until all the windows are clear.
air conditioning system on or off. An indicator light
comes on to show that the air conditioning is on.
The air conditioning can be selected in any mode
as long as the fan switch is on.
On hot days, open the windows to let hot inside air
escape; then close them. This helps to reduce the time
it takes for the vehicle to cool down. It also helps the
system to operate more efficiently.
Press this button to turn the
The air conditioning system removes moisture from the
air, so a small amount of water might drip under the
vehicle while idling or after turning off the engine.
This is normal.
Press this button to turn the
recirculation mode on or off. An indicator light comes
on to show that recirculation is on.
This mode recirculates and helps to quickly cool the
air inside the vehicle. It can be used to help prevent
outside air and odors from entering the vehicle.
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.
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.
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