Hummer 2003 H2 Owner's Manual page 195

(Mode): Press this button to manually select the air
delivery mode to the floor, panel or windshield outlets.
The system will stay in the selected mode until the mode
button is pressed again or the AUTO button is pressed.
Driver's Side Temperature Knob
The driver's side knob is used to adjust the temperature
of the air coming through the system on the driver's
side. The temperature can be adjusted even if the system
is turned off. This is possible since outside air will
always flow through the system as the vehicle is
moving forward unless it is set to recirculation mode.
See "Recirculation" later in this section.
Turn the knob counterclockwise or clockwise to lower
or increase the cabin temperature. The display will show
the temperature setting decreasing or increasing and an
arrow pointing to the driver will be displayed under and
to the left of the temperature setting.
The temperature to the rear seat area is also controlled
by using this knob.
Passenger's Side Temperature Knob
The passenger's side knob can be used to change the
temperature of the air coming through the system on the
passenger's side of the vehicle. The temperature can be
adjusted even if the system is turned off. This is possible
since outside air will always flow through the system
as the vehicle is moving forward unless it is set to
recirculation mode. See "Recirculation" later in this
section.
Turn the knob counterclockwise or clockwise to lower
or increase the cabin temperature. The display will show
the temperature setting decreasing or increasing and an
arrow pointing to the passenger will be displayed under
and to the right of the temperature setting.
The passenger's temperature setting can be set to match
the driver's temperature setting by pressing and holding
the AUTO button for four seconds. Both the driver and
passenger arrows will be displayed.
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