GMC Sierra 3500HD 2001, Owner'S Manual, Page: 110 / 321

3-3
Heater and Air Conditioning Control
System (If Equipped)
Fan Knob
The knob located on the left side of the heating system
control panel regulates the fan speed. The knob has
four speed positions. To increase airflow, turn the knob
toward HI. To decrease airflow, turn it toward LO. To
turn the fan off, turn the knob to OFF. If you have the air
conditioner on, turning the fan knob to OFF also turns
off the A/C compressor.
With the fan knob in OFF while driving, the airflow will
be directed to the floor air outlets. The mode knob will
not redirect airflow to other selected outlet positions.
This is normal operation for OFF.
Temperature Knob
The middle knob on the control panel lets you select the
relative temperature of the air flowing into the passenger
area of your vehicle. This knob will allow you to adjust
the relative air temperature independently of the fan and
knob settings. Turn the knob clockwise, toward the
red area, for warmer air. Turn the knob counterclockwise,
toward the blue area, for cooler air.
Mode Knob
The right knob on the control panel allows you to choose the
direction of air delivery. The knob can be placed in any
position between two mode settings to blend the flow of air.
VENT: This setting directs air through the
instrument panel outlets.
BI
-
LEVEL: This setting divides airflow between
the floor air outlets and instrument panel air outlets.
HEATER: This setting directs air through the
heater floor air outlets.
BLEND: This setting directs air to the heater air
outlets and toward the windshield.
DEFROST: This setting directs air toward
the windshield.