GMC 2001 Sierra 1500 Pickup Owner's Manual page 195

DEFROST: This setting directs most air through
the windshield defroster outlets and some through the
heater outlets. The air conditioning compressor may run
to dehumidify the air to prevent window fogging.
OUTSIDE AIR: Press this button to force the
system to use outside air. Press it again to close off the
outside air.
Pressing the OUTSIDE AIR button will cancel the
RECIRCULATION button.
RECIRCULATION: Press this button to limit
the amount of outside air entering your vehicle. This is
helpful when you are trying to limit odors entering your
vehicle or attempting to quickly cool down the interior.
In the AUTO mode, the system will use recirculation
as necessary to cool the air. Pressing the recirculation
button will change the operation to a manual mode and
the air will recirculate non
to turn off the recirculation feature.
3-8
-
stop. Press this button again
RECIRCULATION may be selected with the fan control
in OFF to limit odors, outside air and dust from entering
your vehicle.
Pressing the RECIRCULATION button will cancel the
OUTSIDE AIR button.
A/C: Press this button to turn the air conditioning
on and off. The system will cool and dehumidify the
air inside the vehicle when the A/C light is on.
When in AUTO, the A/C is automatically engaged
when necessary.
Air conditioning will be automatically disabled when
the outside temperature drops below a level which
air conditioning is ineffective.
Remember that in order for the automatic system to perform
well, it needs A/C to provide cooling performance.