2008 GMC YUKON air conditioning

Remote Vehicle Start
Your vehicle may have a remote starting feature. This
feature allows you to start the engine from outside of the
vehicle. It may also start up the vehicle’s heating or
air conditioning systems and rear window defogger.
Normal operation of the system will return after the key
is turned to the ON/RUN position.
If your vehicle has an automatic climate control system,
the climate control system will default to a heating or
cooling mode depending on the outside temperatures. If
your vehicle does not have an automatic climate control
system, the system will turn on at the setting the vehicle
was set to when the vehicle was last turned off.
During a remote start, if your vehicle has an automatic
climate control system and heated seats, the heated
seats will turn on during colder outside temperatures and
will shut off when the key is turned to ON/RUN. If
your vehicle does not have an automatic climate control
system, during remote start, you will need to manually
turn the heated seats on and off. SeeHeated Seats
on page 1-5for additional information.Laws in some communities may restrict the use of
remote starters. For example, some laws may require a
person using the remote start to have the vehicle in
view when doing so. Check local regulations for
any requirements on remote starting of vehicles.
Do not use the remote start feature if your vehicle is low
on fuel. Your vehicle may run out of fuel.
The RKE transmitter with the remote start button,
provides an increased range of operation. However, the
range may be less while the vehicle is running. As a
result, you may need to be closer to your vehicle to turn
it off, than you were to turn it on.
There are other conditions which can affect the
performance of the transmitter, seeRemote Keyless
Entry (RKE) System on page 2-4for additional
information.
2-8

Instrument Panel Overview...............................3-4
Hazard Warning Flashers................................3-6
Other Warning Devices...................................3-6
Horn.............................................................3-6
Tilt Wheel.....................................................3-6
Turn Signal/Multifunction Lever.........................3-7
Turn and Lane-Change Signals........................3-8
Headlamp High/Low-Beam Changer..................3-9
Flash-to-Pass.................................................3-9
Windshield Wipers..........................................3-9
Rainsense™ II Wipers...................................3-10
Windshield Washer.......................................3-11
Rear Window Wiper/Washer...........................3-12
Cruise Control..............................................3-13
Exterior Lamps.............................................3-16
Headlamps on Reminder................................3-17
Daytime Running Lamps (DRL).......................3-17
Automatic Headlamp System..........................3-18
Fog Lamps..................................................3-19
Auxiliary Roof Mounted Lamp.........................3-19
Instrument Panel Brightness...........................3-20
Dome Lamps...............................................3-20
Dome Lamp Override....................................3-20
Entry Lighting...............................................3-20
Exit Lighting.................................................3-20
Reading Lamps............................................3-21
Electric Power Management...........................3-21Battery Run-Down Protection..........................3-22
Accessory Power Outlet(s).............................3-22
Ashtray(s) and Cigarette Lighter......................3-23
Climate Controls............................................3-23
Climate Control System.................................3-23
Dual Automatic Climate Control System...........3-26
Outlet Adjustment........................................
.3-33
Rear Air Conditioning and Heating System.......3-33
Rear Air Conditioning and Heating System
and Electronic Climate Controls...................3-35
Warning Lights, Gages, and Indicators............3-37
Instrument Panel Cluster................................3-38
Speedometer and Odometer...........................3-39
Trip Odometer..............................................3-39
Tachometer.................................................3-39
Safety Belt Reminders...................................3-39
Airbag Readiness Light..................................3-40
Passenger Airbag Status Indicator...................3-41
Charging System Light..................................3-43
Voltmeter Gage............................................3-44
Brake System Warning Light..........................3-44
Antilock Brake System
Warning Light...........................................3-46
StabiliTrak
®Indicator Light..............................3-46
Engine Coolant Temperature Gage..................3-47
Tire Pressure Light.......................................3-47
Section 3 Instrument Panel
3-1

6(Floor):This mode directs most of the air to the
oor outlets, with some of the air directed to the
windshield, side window outlets, and second row oor
outlets. In this mode, the system will automatically select
outside air. Recirculation cannot be selected when in
Floor Mode.
The right knob can also be used to select defog or
defrost mode. For more information, see “Defogging and
Defrosting” later in this section.
By positioning the right knob between two modes, a
combination of those two modes is selected.
The air conditioning compressor will be on unless the
outside temperature is close to freezing.
9(Fan):Turn the left knob clockwise or
counterclockwise to increase or decrease the fan speed.
Turn the knob all the way counterclockwise to turn the
front system off.
?(Recirculation):Press this button to turn the
recirculation mode on. When the button is pressed, an
indicator light will come on.This mode keeps outside air from entering the vehicle.
It can be used to reduce outside air and prevent
odors from entering the vehicle. Recirculation may also
help cool the air inside the vehicle more quickly once
the temperature inside the vehicle is less than the
outside temperature.
The recirculation mode cannot be used with oor,
defrost, or defogging modes. If you try to select
recirculation in one of those modes, the indicator will
ash three times and turn off. The air conditioning
compressor will also come on when this mode is
activated. While in recirculation mode the windows may
fog when the weather is cold and damp. To clear the
fog, select either the defog or defrost mode and increase
the fan speed. Recirculation mode can be turned off
by pressing the button again, or turning off the engine.
AUX (Auxiliary):Pressing this button will turn the
rear heating and air conditioning on. SeeRear
Air Conditioning and Heating System on page 3-33or
Rear Air Conditioning and Heating System and
Electronic Climate Controls on page 3-35for more
information.
3-24

Temperature Control:Rotate the thumbwheels up or
down to increase or decrease the temperature on
the driver’s side or the passenger side of the vehicle for
the dual zone system, if equipped. Otherwise, turn
the center knob clockwise or counterclockwise to
increase or decrease the temperature inside the vehicle.
#(Air Conditioning):Press this button on the left
knob to turn the air conditioning system on or off. When
A/C is pressed, an indicator light comes on to show
that the air conditioning has been activated.
On hot days, open the windows to let hot inside air
escape; then close them. This helps to reduce the time
it takes for your vehicle to cool down. It also helps
the system to operate more efficiently.
The air conditioning system removes moisture from the
air, so a small amount of water might drip underneath
the vehicle while idling or after turning off the engine.
This is normal.
Defogging and Defrosting
Fog on the inside of the windows is a result of high
humidity (moisture) condensing on the cool window
glass. This can be minimized if the climate control
system is used properly. There are two modes to clear
fog or frost from your windshield. Turn the right knob
clockwise to select the defog or defrost mode.
-(Defog):The defog mode is used to clear the
windows of fog or moisture and warm the passengers.
This mode directs air to the windshield, oor outlets,
and side window vents. When this mode is selected, the
system turns off recirculation and runs the air
conditioning compressor unless the outside temperature
is close to freezing. The recirculation mode cannot be
selected while in the defog mode. Do not drive the
vehicle until all the windows are clear.
0(Defrost):The defrost mode is used to remove fog
or frost from the windshield more quickly. This mode
directs a portion of the air to the windshield and
side window vents and some to the oor vents. In this
mode, the system will automatically force outside air into
the vehicle. The recirculation mode cannot be selected
while in the defrost mode. The air conditioning
compressor will run automatically in this setting, unless
the outside temperature is close to freezing. Do not
drive the vehicle until all the windows are clear.
3-25

When AUTO is selected, the air conditioning
operation and air inlet will be automatically
controlled. The air conditioning compressor will run
when the outside temperature is over about
40°F (4°C). The air inlet will normally be set to
outside air. If it is hot outside, the air inlet may
automatically switch to recirculate inside air to help
quickly cool down the vehicle. The light on the
button will illuminate in recirculation.
2. Set the driver’s and passenger’s temperature.
To nd your comfort setting, start with a 74°F (23°C)
temperature setting and allow about 20 minutes
for the system to regulate. Use the driver’s or
passenger’s temperature buttons to adjust the
temperature setting as necessary. If you choose the
temperature setting of 60°F (15°C), the system
will remain at the maximum cooling setting. If you
choose the temperature setting of 90°F (32°C),
the system will remain at the maximum heat setting.
Choosing either maximum setting will not cause
the vehicle to heat or cool any faster.Be careful not to cover the solar sensor located on the
top of the instrument panel near the windshield. This
sensor regulates air temperature based on sun load and
also turns on the headlamps. For more information on
the solar sensor, see “Sensors” later in this section.
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 engine coolant
temperature. Pressing the fan switch will override this
delay and change the fan to a selected speed.
O(On/Off):Press this button to turn off the climate
control system. Outside air will still enter the vehicle, and
will be directed to the oor. This direction can be
changed by pressing the mode button. Recirculation
can be selected once vent or bi-level mode has
been selected. The temperature can also be adjusted
using either temperature button. If the air delivery mode
or temperature settings are adjusted with the system
off, the display will illuminate briey to show you
the settings and then return off. Press the on/off button
or the up down arrows on the fan switch, the defrost
button, AUTO button, or the air conditioning button
to turn the system on when it is off.
3-28

@(Recirculation):Press this button to turn the
recirculation mode on. When the button is pressed, an
indicator light comes on.
This mode keeps outside air from entering the vehicle.
It can be used to reduce outside air and prevent
odors from entering the vehicle. Recirculation may also
help cool the air inside the vehicle more quickly once
the temperature inside the vehicle is less than the
outside temperature.
The recirculation mode cannot be used with oor,
defrost, or defogging modes. If you try to select
recirculation in one of those modes, the indicator will
ash three times and turn off. The air conditioning
compressor will also come on when this mode is
activated. While in recirculation mode the windows may
fog when the weather is cold and damp. To clear the
fog, select either the defog or defrost mode and increase
the fan speed. Recirculation mode can be turned off
by pressing the button again, or turning off the engine.Air Conditioning
#
(Air Conditioning):Press this button to turn the
air conditioning (A/C) compressor on and off. When
air conditioning is selected, an indicator light comes on
to show that the air conditioning has been activated.
Pressing this button when the outside temperature is too
cool for air conditioning will make the air conditioning
indicator ash three times and then turn off to show that
the air conditioning mode is not available. If the air
conditioning is on and the outside temperature drops
below a temperature which is too cool for air
conditioning to be effective, the air conditioning light will
turn off to show that the air conditioning mode has
been canceled.
On hot days, open the windows long enough to let hot
inside air escape. This helps to reduce the time it
takes for your vehicle to cool down. It also helps the
system to operate more efficiently.
The air conditioning system removes moisture from the
air, so a small amount of water might drip underneath
the vehicle while idling or after turning off the engine.
This is normal.
3-30

Defogging and Defrosting
Fog on the inside of the windows is a result of high
humidity (moisture) condensing on the cool window
glass. This can be minimized if the climate control
system is used properly. There are two modes to clear
fog or frost from your windshield.
Use the mode up and down arrows to select the defog
or defrost modes.
-(Defog):The defog mode is used to clear the
windows of fog or moisture and warm the passengers.
This mode directs air to the windshield, oor outlets,
and side window vents. When this mode is selected, the
system turns off recirculation and runs the air
conditioning compressor unless the outside temperature
is close to freezing. The recirculation mode cannot be
selected while in the defog mode. Do not drive the
vehicle until all the windows are clear.
0(Defrost):Press this button to remove fog or frost
from the windshield more quickly. This mode directs
a portion of the air to the windshield and side window
vents and some to the oor vents. In this mode, the
system will automatically force outside air into the
vehicle. The recirculation mode cannot be selected while
in the defrost mode. The air conditioning compressor
will run automatically in this setting, unless the outside
temperature is close to freezing. Do not drive the
vehicle until all the windows are clear.
Rear Window Defogger
The rear window defogger uses a warming grid to
remove fog from the rear window.
<(Rear Window Defogger):Press this button to
turn on the rear window defogger. It will automatically
turn off several minutes after it has been activated. The
defogger can also be turned off by pressing the
button again or by turning off the engine. Do not drive
the vehicle until all the windows are clear.
If your vehicle has heated outside rearview mirrors, the
mirrors will heat to help clear fog or frost from the
surface of the mirror when the rear window defog button
is pressed.
Notice:Do not use a razor blade or sharp object to
clear the inside rear window. Do not adhere
anything to the defogger grid lines in the rear glass.
These actions may damage the rear defogger.
Repairs would not be covered by your warranty.
3-32

Outlet Adjustment
Use the air outlets located in the center and on the side
of your instrument panel to direct the airow.
Operation Tips

Keep the hood and front air inlets free of ice, snow,
or any other obstruction (such as leaves). The
heater and defroster will work far better, reducing
the chance of fogging the inside of your windows.
When you enter a vehicle in cold weather, press the
fan up button to the maximum fan level before
driving. This helps clear the intake ducts of snow
and moisture, and reduces the chance of fogging
the inside of your window.
Keep the air path under the front seats clear of
objects. This helps air to circulate throughout
your vehicle.
Adding outside equipment to the front of your
vehicle, such as hood-air deectors, may affect the
performance of the heating and air conditioning
system. Check with your dealer before adding
equipment to the outside of your vehicle.
Rear Air Conditioning and Heating
System
If your vehicle has this system, the rear controls are
three knobs located in the headliner. The system can be
controlled from the front controls as well as the rear
controls.
To turn the system on, press the AUX button on the
front climate control system, an indicator will be
lit. Pressing the AUX button the rst time will turn the
rear system on in a mimic mode. In this mode, the
airow in the rear will be approximately the same
direction, temperature, and fan speed as the front.
Pressing the AUX button again will turn the rear system
and the indicator off.
3-33