GMC 2007 Sierra - Manual (Page 232)

Mode Control
To change the current mode, select one of the
following:
H
(Vent): This mode directs air to the instrument
panel outlets.
) (Bi-Level): This mode directs half of the air to
the instrument panel outlets; then directs most
of the remaining air to the floor outlets. A little air
is directed toward the windshield and the side
window outlets. Cooler air is directed to the upper
outlets and warmer air to the floor outlets.
6
(Floor): This mode directs most of the air to
the floor outlets with a little air directed to the
windshield and the side window outlets.
h (Recirculation): The recirculation mode is
used to recirculate the air inside of your vehicle.
Use this mode to help prevent outside odors
and/or dust from entering your vehicle or to help
cool the air inside of your vehicle more quickly.
Press this button to turn the recirculation mode on
or off. The light on the recirculation button will
illuminate. Recirculation cannot be used in floor,
defog or defrost modes. An indicator on the button
will light up, flash three times and turn off when
recirculation is selected in these modes. 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 fan speed.
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