2002 GMC YUKON DENALI air conditioning

2-80 Low Coolant
This message is displayed
when the cooling system is
low on coolant.
The engine may overheat. See ªEngine Coolantº in
the Index and have your vehicle serviced as soon as
you can.
Check Coolant Temp
This message is displayed
when the cooling system
temperature gets hot.
Check the coolant temperature gage and the coolant
level. See ªEngine Coolant,º ªEngine Coolant
Temperature Gageº and ªEngine Overheatingº in the
Index for further information.
Engine Overheated
This message is displayed
when the cooling system
temperature gets too hot.
This message will be displayed after the air conditioning
system has automatically turned off for the engine
coolant protection mode. See ªEngine Overheatingº in
the Index for further information.
Reduced Engine Power
This message is displayed
when the cooling system
temperature gets too hot
and the engine further
enters the engine coolant
protection mode.
See ªEngine Overheatingº in the Index for
further information.

3-
3-1
Section 3 Comfort Controls and Audio Systems
In this section, you'll find out how to operate the comfort control and audio systems offered with your vehicle.
Be sure to read about the particular systems supplied with your vehicle.
3
-2 Comfort Controls
3
-2 Electronic Climate Control System
3
-8 Air Conditioning
3
-8 Heating
3
-9 Defogging and Defrosting
3
-9 Rear Window Defogger
3
-10 Ventilation System
3
-11 Audio Systems
3
-11 Setting the Clock
3
-12 AM-FM Stereo with Cassette Tape
Player (Bose
)3
-17 Rear Seat Audio (RSA)
3
-19 Compact Disc Changer
3
-22 Theft-Deterrent Feature
3
-24 Audio Steering Wheel Controls
3
-25 Understanding Radio Reception
3
-25 Tips About Your Audio System
3
-26 Care of Your Cassette Tape Player
3
-27 Care of Your Compact Discs
3
-27 Care of Your Compact Disc Player
3
-27 Fixed Mast Antenna

3-3
Mode Knob - Manual Operation
The right knob on the control panel allows you to
choose the direction of air delivery.
You can choose to set the climate control system
operations manually, or let the system work
automatically by turning the knob on the control panel
to AUTO. See ªMode Knob
-- Automatic Operationº
later in this section.
(Vent): This setting directs most of the air through
the instrument panel outlets and a small amount through
the floor outlets.
(Bi-level): This setting directs air through the
floor outlets as well as the instrument panel outlets.
(Floor): This setting directs most of the airflow
through the floor outlets and some air through the
windshield defroster outlets. Recirculation will not be
available in this mode. See ªRecirculationº following
for more information.
(Blend): This setting divides airflow equally
between the floor outlets and the windshield defroster
outlets. The air conditioning compressor may run to
dehumidify the air to prevent window fogging.
Recirculation will not be available in this mode. See
ªRecirculationº following for more information.
(Defrost): This setting directs most air through the
windshield defroster outlets and some through the floor
outlets. The air conditioning compressor may run to
dehumidify the air to prevent window fogging.
Recirculation will not be available in this mode. See
ªRecirculationº following for more information.
Mode Buttons
(Outside air): Press this button, located
under the fan knob, to use outside air. Using outside
air will limit stale air odors and help to prevent
excessively humid interior air (from wet boots or
clothing or maximum passenger loads) from being
redirected onto windows.
Pressing the outside air button will cancel the
recirculation button.

3-4
(Recirculation): Press this button to limit
the amount of outside air entering the vehicle to a very
small amount. This setting helps limit odors entering the
vehicle and will assist in reaching a comfortable
temperature in very hot temperature conditions.
Pressing recirculation will cause the system to
recirculate interior air continuously and may cause the
vehicle windows to fog if the passenger compartment
floor is excessively wet.
A/C (Air Conditioning): 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 at which
air conditioning is effective.Pressing the recirculation button will cancel outside air
operation. To return to normal system operation and to
prevent stale passenger compartment air, be sure to
return to the outside air position.
To help reduce window fogging, recirculation will not
be available in floor, blend or defrost modes. If the
recirculation button is pressed in these modes, the LED
indicator for recirculation will flash three times
indicating that forced outside air is activated and
recirculation is not available.
If the air conditioning system is activated and system
demand is high in situations such as city traffic, idling,
or very hot weather, the system will automatically
switch from outside air to recirculation. The LED
indicator will not change. After demand on the system is
reduced, the system will return back to outside air.

3-5
Mode Knob - Automatic Operation
When the system is set in AUTO mode, sensors will
control the air delivery mode. Air will come primarily
from the floor or instrument panel outlets, with some air
directed to the windshield to prevent fogging.
When the system is in AUTO mode, the air conditioning
light will turn on, and the recirculation and outside air
lights will turn off. With the system in full automatic
control (both the fan and mode knobs in AUTO), you
still have the ability to override any function. However,
continually overriding the outside air or the A/C
compressor will limit the ability of the system to cool
the vehicle quickly.
If you push a button for a function which is not
available, the light next to that button will flash three
times to alert you that it's not available.
To find your comfort zone, start with the 74
F (23
C)
setting and allow about 20 minutes for the system to
adjust the temperature if necessary.With the automatic setting, the air conditioning
compressor automatically cycles when needed to cool
the air. In cold weather, when the system senses the
need for heat, the airflow will be directed out the floor
outlets. As the interior temperature approaches a desired
setting, the fan speed will decrease. To maintain interior
comfort, the airflow will adjust between the instrument
panel outlets and floor outlets. On bright sunny days
in cool weather, the airflow may come out of the
instrument panel and the floor outlets (bi
-level mode)
to maintain comfort and prevent stuffiness.
To avoid blowing cold air in cold weather, the system
will delay turning on the fan until warm air is available.
The length of delay depends on the outside air
temperature, engine coolant temperature or the time
since the engine was last started. As the coolant
warms up, the fan speed will gradually increase and
air will flow from the floor outlets, with some airflow
to the windshield to prevent fogging under most
normal conditions.
Be careful not to put anything over the solar sensor
located near the center of the instrument panel.
This sensor is used by the automatic system to
regulate temperature.

3-6 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 ControlTo 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.

3-7 Rear Air Conditioning and Heating Systems
with Electronic Climate Control System
(Without Sunroof)
Front Control
Rear ControlWith this system the rear passengers can control the
temperature of the air flow for the rear seating area.
The climate control panels have three knobs.
To adjust the fan speed, turn the fan knob located on
the left side of the control panel to the desired setting.
The system also has a front AUTO setting that can
automatically change the temperature of the rear seating
area based on information received from the front
control panel. The OFF setting, located on the front
climate control panel, also allows the driver to turn off
the rear passenger seat controls from the front seat.
To adjust the air temperature, turn the temperature knob
located on the center of the control panel clockwise
toward 82
F (28
C) for warmer air and
counterclockwise toward 66
F (19
C) for cooler air.
To direct the airflow, turn the right knob located on
the control panel clockwise or counterclockwise to the
desired mode. Generally, the upper vents are used for air
conditioning and the floor vents for heating. The control
knob can be set to any blend setting.
For rear control operation, use the above instructions.

3-8 Air Conditioning
On hot days, open the windows long enough to let hot
air inside escape. This reduces the time it takes for your
vehicle to cool down. Then keep your windows closed
for the air conditioner to work its best.
The A/C button, located below the mode knob, allows
the air coming into your vehicle to be cooled. This
setting is useful for normal cooling on hot days.
Use A/C with recirculation on to allow the air inside
your vehicle to be recirculated. This setting will help to
maximize your air conditioner's performance and your
vehicle's fuel economy. This setting also cools the air
the fastest and can be used to keep unwanted odors
and/or dust from entering the vehicle.
When using the air conditioner, turn off the recirculation
setting and use the outside air setting after the vehicle
reaches a comfortable interior temperature. When the
right knob on the control panel is between floor and
defrost, the recirculation feature will not function.
This helps reduce window fogging.Passenger Compartment Air Filter
Your vehicle is equipped with a passenger compartment
air filter which filters outside air entering the vehicle.
For information on replacing the filter see ªPassenger
Compartment Air Filterº in the Index.
Heating
The heater works best if you keep your windows closed
while using it. On cold days, use the floor or bi
-level
(mode knob set between vent and floor) setting with the
temperature knob in the red area.
On cold days, approximately 32
F (
-0
C) or lower,
you may experience differences in how the transmission
shifts until the engine is warm. This feature
automatically reduces the time it takes for the engine to
reach normal operating temperature and shortens the
time it takes the heater to reach full output.
If you use the engine coolant heater before starting your
engine in cold weather, 20
F (
-8
C) or lower, the
heating system will produce warmer air faster to heat the
passenger compartment.
The use of an engine coolant heater also reduces the
time it takes for the engine to reach normal operating
temperature. For more information, see ªEngine Coolant
Heaterº in the Index.