2001 GMC YUKON air condition

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The following situations can cause the transmission to
operate at higher temperatures:

Towing a trailer

Hot outside air temperatures

Hauling a heavy load

Low transmission fluid level

High transmission fluid level

Restricted air flow to the radiator and the auxiliary
transmission oil cooler (if equipped).
A temporary solution to hotter transmission operating
temperatures may be to let the transmission cool down.
If the transmission is operated at higher temperatures on
a frequent basis, see ªScheduled Maintenanceº in the
Index for the proper transmission maintenance intervals.
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 Coolantº and ªEngine Coolant
Temperature Gageº in the Index. See 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.

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
-3 Heater and Air Conditioning Comfort
Controls (If Equipped)
3
-5 Electronic Climate Control System
(If Equipped)
3
-11 Air Conditioning
3
-12 Heating
3
-12 Defogging and Defrosting
3
-12 Rear Window Defogger (If Equipped)
3
-13 Ventilation System
3
-15 Audio Systems
3
-15 Setting the Clock for Systems with
SET Button
3
-15 Setting the Clock for Systems with HR and
MN Buttons3
-15 AM-FM Stereo
3
-17 AM-FM Stereo with Cassette Tape Player
(If Equipped)
3
-19 AM-FM Stereo with Cassette Tape Player and
Automatic Tone Control (If Equipped)
3
-24 AM-FM Stereo with Compact Disc Player and
Automatic Tone Control (If Equipped)
3
-28 Rear Seat Audio (If Equipped)
3
-29 Remote Cassette Player (If Equipped)
3
-31 Theft-Deterrent Feature (If Equipped)
3
-33 Understanding Radio Reception
3
-33 Tips About Your Audio System
3
-34 Care of Your Cassette Tape Player
3
-35 Care of Your Compact Discs
3
-35 Care of Your Compact Disc Player
3
-35 Fixed Mast Antenna

3-3 Heater and Air Conditioning Comfort
Controls (If Equipped)
Fan Knob
The knob on the left side of the control panel adjusts the
fan speed. To increase airflow, turn the knob clockwise.
To decrease airflow, turn it counterclockwise. To turn
the fan off, turn the knob to OFF.
Temperature Knob
The middle knob on the control panel lets you select the
temperature of the air flowing into the passenger area.
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.
PANEL: This setting directs the air through the
instrument panel outlets.
BI-LEVEL: Air is delivered through the
instrument panel outlets and the heater floor outlets.
The air flow can be divided between PANEL and
HEATER depending upon where the knob is placed
between the settings. Pressing the A/C button while
in this mode causes cooler air to come out of the
instrument panel outlets and warmer air to come
out of the heater floor outlets.
HEATER: This setting directs most of the
warmed air through the heater floor outlets as well as
some air through the windshield defroster outlets and
side window defroster outlets.
BLEND: Airflow is delivered through the heater
floor outlets, the windshield defroster outlets and the
side window defroster outlets. The air flow can be
divided between HEATER and DEFROST depending
upon where the knob is placed between the settings.
The air conditioning compressor may run to dehumidify
the air to prevent window fogging.

3-4
DEFROST: This setting directs most of the air
through the windshield defroster outlets, side window
defroster outlets and some air through the heater outlets.
When in the DEFROST mode, the air conditioning
compressor may run to dehumidify the air to prevent
window fogging.
OUTSIDE AIR: Press this button to direct
the system to use outside air. This is the setting which
should be used for normal operation.
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. Pressing RECIRCULATION will
recirculate air continuously.
RECIRCULATION is used when the fan control is OFF
to limit odors, outside air and dust from entering your
vehicle. All button lights will go off. The last setting
selected will activate when the blower is turned back on.
Pressing the RECIRCULATION button will cancel
the OUTSIDE AIR button. To return to normal
operation and to prevent stale air, be sure to return
the OUTSIDE AIR.Between HEATER and BLEND mode, outside air is forced
to reduce window fogging. If the RECIRCULATION
button is pressed, the LED indicator will flash three times
indicating that forced outside air is activated and
RECIRCULATION is not available.
The auto recirculation feature will activate when the
following are true:

the air conditioning system is activated,

the OUTSIDE AIR button is on, and

the vehicle load is high due to city traffic, extended
idling or hot weather.
The system will automatically switch to the recirculation
mode to lower the system load and improve interior
comfort. The OUTSIDE AIR and RECIRCULATION
button LEDs will not change. The system will return
to the OUTSIDE AIR function when the system load
is reduced.
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.
Air conditioning will be automatically disabled when
the outside temperature drops below a level at which
air conditioning is effective.

3-6
Mode Knob - Automatic Operation
The right knob on the control panel allows you to
choose the direction of air delivery. When the system is
set for automatic operation, 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 turn off. With the system in full auto 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 of 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 air outlets and floor outlets. On bright
sunny days in cool weather, the airflow may come out
of the air conditioning and 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 blower
fan speed will gradually increase and air will flow from
the heater 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 around the center of the instrument panel.
This sensor is used by the automatic system to
regulate temperature.

3-7
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 yourself, or let the system work for you
by placing the system in AUTO mode. See ªMode
Knob
- Automatic Operationº earlier in this section.
PANEL: This setting directs most of the air
through the instrument panel outlets and a small amount
through the floor outlets.
BI-LEVEL: Air is delivered through the heater
floor outlets as well as the instrument panel outlets.
HEATER: This setting directs most of the warmed
air through the heater floor outlets and some air through
the windshield defroster outlets.
BLEND: Airflow is divided equally between the
heater floor outlet and the windshield defroster outlets.
The air conditioning compressor may run to dehumidify
the air to prevent window fogging.
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
-stop. Press this button again
to turn off the recirculation feature.
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.

3-8
Air conditioning will be automatically disabled when
the outside temperature drops below a level at which
air conditioning is ineffective.
Remember that in order for the automatic system to perform
well, it needs A/C to provide cooling performance.
Rear Air Conditioning and Heating Systems
(If Equipped)
If your vehicle has one of these systems, you can increase
and decrease the airflow at the rear vents. Depending on
the system you have and the setting selected, you can
send cooled or heated air to the rear of the vehicle.
Rear Air Conditioning (Without Rear Heater)
(If Equipped)
Front ControlTo increase and decrease the flow of cooled air to the
rear vents, turn the knob to the blower speed you want.
The knob has three speed positions. To increase the flow
of cooled air, turn the switch toward ª3º. To decrease
the flow of cooled air, turn it toward ª1º. To turn the
fan off, turn the knob to OFF.
To operate the rear system using the front control,
just turn the knob to the blower position you want.
Rear Control
To use the rear control, first turn the front control to
REAR. Then, the rear control can be used to increase
and decrease the airflow.

3-9
Rear Air Conditioning and Rear Heater
(If Equipped)
If your vehicle has the rear air conditioning and rear
heater system combination, controls are provided to
regulate temperature, location and fan speed.
Front Control
To adjust the airflow speed, turn the fan control knob
located on the left side to the desired setting.
To activate the second seat control system, turn the fan
knob on the front overhead control to REAR.
To regulate the airflow location, adjust the right control
on the control. Turn the knob clockwise for floor vent
airflow or counterclockwise for headliner vent airflow. 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.
To adjust the air temperature, turn the temperature knob
on the center of the control panel.
For warmer air, turn the knob clockwise toward red. For
cooler air, turn the knob counterclockwise toward blue.
Rear Control
The rear control works just like the front control. It will
allow second seat passengers to adjust the controls as
they desire. To use the rear control, first turn the front
control knob to REAR.