2008 GMC YUKON cooling

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

Liftgate/Liftglass
{CAUTION:
It can be dangerous to drive with the liftglass
or liftgate open because carbon monoxide
(CO) gas can come into your vehicle. You
cannot see or smell CO. It can cause
unconsciousness and even death.
If you must drive with the liftglass or liftgate
open, or if electrical wiring or other cable
connections must pass through the seal
between the body and the liftglass or liftgate:
Make sure all other windows are shut.
Turn the fan on your heating or cooling
system to its highest speed with the
recirculation mode off. That will force
outside air into your vehicle. SeeClimate
Control System on page 3-23orDual
Automatic Climate Control System on
page 3-26.
CAUTION: (Continued)
CAUTION: (Continued)

If you have air outlets on or under the
instrument panel, open them all the way.
If your vehicle has a power liftgate, disable
the power liftgate function.
SeeEngine Exhaust on page 2-47.
If your vehicle has a power liftgate, seePower Liftgate
on page 2-15.
To unlock the liftgate, use the power door lock switch or
press the door unlock button on the Remote Keyless
Entry (RKE) transmitter twice. SeeRemote Keyless
Entry (RKE) System Operation on page 2-5.
2-13

Power Liftgate
Power Liftgate Operation
{CAUTION:
It can be dangerous to drive with the liftgate
open because carbon monoxide (CO) gas can
come into your vehicle. You cannot see or
smell CO. It can cause unconsciousness and
even death.
If you must drive with the liftgate open, or if
electrical wiring or other cable connections
must pass through the seal between the body
and the liftgate:
Make sure all other windows are shut.
Turn the fan on your heating or cooling
system to its highest speed with the
recirculation mode off. That will force
outside air into your vehicle. See Climate
Control System in the index.
CAUTION: (Continued)
CAUTION: (Continued)

If you have air outlets on or under the
instrument panel, open them all the way.
If your vehicle has a power liftgate, disable
the power liftgate function.
SeePower Liftgate on page 2-15.
On vehicles with a power liftgate the button is located
on the center console.
The vehicle must be in PARK (P) to use the power
liftgate feature.
&:Press the top of the button to open or close the
power liftgate.
OFF:Press the bottom of the button for manual
operation of the power liftgate.
2-15

Reading Lamps
If your vehicle has reading lamps they are located on
the overhead console.
To turn on the reading lamps, press the button located
next to each lamp. To turn them off, press the button
again.
Your vehicle may also have reading lamps in other
locations. To turn the lamps on or off, press the button
located next to the lamp.
The lamps are xed and cannot be adjusted.
Electric Power Management
The vehicle has Electric Power Management (EPM) that
estimates the battery’s temperature and state of
charge. It then adjusts the voltage for best performance
and extended life of the battery.
When the battery’s state of charge is low, the voltage is
raised slightly to quickly put the charge back in. When
the state of charge is high, the voltage is lowered slightly
to prevent overcharging. If the vehicle has a voltmeter
gage or a voltage display on the Driver Information
Center (DIC), you may see the voltage move up
or down. This is normal. If there is a problem, an alert
will be displayed.The battery can be discharged at idle if the electrical
loads are very high. This is true for all vehicles. This is
because the generator (alternator) may not be
spinning fast enough at idle to produce all the power
that is needed for very high electrical loads.
A high electrical load occurs when several of the
following loads are on: headlamps, high beams, fog
lamps, rear window defogger, climate control fan at high
speed, heated seats, engine cooling fans, trailer
loads, and loads plugged into accessory power outlets.
EPM works to prevent excessive discharge of the
battery. It does this by balancing the generator’s output
and the vehicle’s electrical needs. It can increase
engine idle speed to generate more power, whenever
needed. It can temporarily reduce the power demands of
some accessories.
Normally, these actions occur in steps or levels, without
being noticeable. In rare cases at the highest levels
of corrective action, this action may be noticeable to the
driver. If so, a Driver Information Center (DIC)
message might be displayed, such as Battery Saver
Active or Service Battery Charging System. If this
message is displayed, it is recommended that the driver
reduce the electrical loads as much as possible. See
DIC Warnings and Messages on page 3-64.
3-21

Ashtray(s) and Cigarette Lighter
The front ashtray is located near the center of the
instrument panel or on the front console, if equipped.
Pull on the ashtray door to open it.
Notice:If you put papers, pins, or other ammable
items in the ashtray, hot cigarettes or other
smoking materials could ignite them and possibly
damage your vehicle. Never put ammable items in
the ashtray.
To remove the front ashtray pull the ashtray up.
To use the cigarette lighter, push it in all the way, and
let go. When it’s ready, it will pop back out by itself.
Notice:Holding a cigarette lighter in while it
is heating does not let the lighter back away from
the heating element when it is hot. Damage from
overheating can occur to the lighter or heating
element, or a fuse could be blown. Do not hold a
cigarette lighter in while it is heating.
Climate Controls
Climate Control System
The heating, cooling, defrost, defog and ventilation of
your vehicle can be controlled with this system.
Manual Operation
Turn the right knob clockwise or counterclockwise to
direct the airow inside of the vehicle.
To change the current mode, select one of the following:
H(Vent):This mode directs air to the instrument
panel outlets.
)(Bi-Level):This mode directs half of the air to the
instrument panel outlets and to the oor outlets. The
ow can be divided between vent and oor outlets
depending upon where the knob is placed between the
settings. A little air is directed towards the windshield
and side window outlets. Cooler air is directed to
the upper outlets and warmer air to the oor outlets.
3-23

Rear Window Defogger
The rear window defogger uses a warming grid to
remove fog from the rear window.
<(Rear Window Defogger):Press this button on
the right knob to turn on the rear window defogger. The
system 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 anything sharp on the inside of
the rear window. If you do, you could cut or
damage the warming grid, and the repairs would not
be covered by your warranty. Do not attach a
temporary vehicle license, tape, a decal or anything
similar to the defogger grid.
Dual Automatic Climate Control
System
The heating, cooling, and ventilation in your vehicle
can be controlled with this system. Your vehicle also has
a ow-through ventilation system described later in
this section.
If your vehicle is a Two-mode Hybrid, see the Two-mode
Hybrid manual for more information.
Different climate control settings can be selected for the
driver and passengers.
3-26

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

Engine Coolant Temperature Gage
This gage shows the engine coolant temperature.
It also provides an indicator of how hard your vehicle is
working. During a majority of the operation, the gage
will read 210°F (100°C) or less. If you are pulling a load
or going up hills, it is normal for the temperature to
uctuate and approach the 250°F (122°C) mark. If the
gage reaches the 260°F (125°C) mark, it indicates
that the cooling system is working beyond its capacity.
SeeEngine Overheating on page 5-31.
If your vehicle is a Two-mode Hybrid, see the Two-mode
Hybrid manual for more information.
Tire Pressure Light
This light comes on briey
when the engine is started.
This light will also come on when one or more of your
tires are signicantly underinated.
A tire pressure message in the Driver Information
Center (DIC), may accompany the light. SeeDIC
Warnings and Messages on page 3-64for more
information.
Stop and check your tires as soon as it is safe to do so.
If underinated, inate to the proper pressure. See
Tires on page 5-64for more information.
If a problem is detected with the Tire Pressure Monitor
System, this light will ash for approximately
60 seconds and then stay on solid for the remainder of
the ignition cycle. SeeTire Pressure Monitor System
on page 5-73for more information. United States
Canada
3-47