GMC 2002 Yukon Denali Owner's Manual page 182

Rear Air Conditioning and Rear Heater
(With Sunroof)
Your vehicle has the rear air conditioning and rear
heater system combination. Controls are provided to
regulate the temperature, the air delivery location and
the fan speed.
Front Control
3-6
To adjust the fan speed, turn the fan knob located on the
left side to the desired setting.
To select the direction of airflow turn the right knob
located on the control panel to the desired setting.
Generally, the upper vents are used for air conditioning
and the floor vents for heating. The knob can be set to
any blend setting.
To adjust the air temperature, turn the temperature knob
on the center of the control panel to the desired setting.
For warmer air, turn the knob clockwise toward red. For
cooler air, turn the knob counterclockwise toward blue.