air conditioning GMC SIERRA 2008 User Guide

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 the windshield.
Use
HandGto select the defog or defrost modes.
-(Defog):Press this button 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 your
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):If your vehicle has this
feature, press this button to turn the defogger on or
off. It automatically turns off several minutes after it has
been activated. The defogger can also be turned off
by turning the engine off. Do not drive the vehicle until
all the windows are clear.
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.
Heated Mirrors: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. SeeOutside Power
Mirrors on page 2-59.
Outlet Adjustment
Use the air outlets located in the center and on the side
of the instrument panel to direct the airow.
3-33

is reconnected. This message also clears if you
acknowledge it. If this message still displays, either your
vehicle or the trailer needs service. See your
dealer/retailer.
See “Integrated Trailer Brake Control System” under
Towing a Trailer on page 4-55for more information.
DRIVER DOOR OPEN
This message displays and a chime sounds if the driver
door is not fully closed and the vehicle is in a drive
gear. Stop and turn off the vehicle, check the door for
obstructions, and close the door again. Check to
see if the message still appears on the DIC.
ENGINE HOT A/C (Air Conditioning)
TURNED OFF
This message displays when the engine coolant
becomes hotter than the normal operating temperature.
SeeEngine Coolant Temperature Gage on page 3-46.
To avoid added strain on a hot engine, the air
conditioning compressor automatically turns off. When
the coolant temperature returns to normal, the air
conditioning compressor turns back on. You can
continue to drive your vehicle.
If this message continues to appear, have the system
repaired by your dealer/retailer as soon as possible
to avoid damage to the engine.
ENGINE OVERHEATED IDLE ENGINE
Notice:If you drive your vehicle while the engine is
overheating, severe engine damage may occur. If
an overheat warning appears on the instrument
panel cluster and/or DIC, stop the vehicle as soon
as possible. SeeEngine Overheating on page 5-30
for more information.
This message displays when the engine coolant
temperature is too hot. Stop and allow the vehicle to
idle until it cools down. SeeEngine Coolant
Temperature Gage on page 3-46.
SeeOverheated Engine Protection Operating Mode (V8
Engines Only) on page 5-33for information on driving
to a safe place in an emergency.
ENGINE OVERHEATED STOP ENGINE
Notice:If you drive your vehicle while the engine
is overheating, severe engine damage may occur. If
an overheat warning appears on the instrument
panel cluster and/or DIC, stop the vehicle as soon
as possible. SeeEngine Overheating on page 5-30
for more information.
This message displays and a chime sounds if the
engine cooling system reaches unsafe temperatures for
operation. Stop and turn off the vehicle as soon as it
is safe to do so to avoid severe damage. This message
clears when the engine has cooled to a safe operating
temperature.
3-65

Driving with a Trailer
{CAUTION:
If you have a rear-most window open and you
pull a trailer with your vehicle, carbon
monoxide (CO) could come into your vehicle.
You cannot see or smell CO. It can cause
unconsciousness or death. SeeEngine
Exhaust on page 2-53. To maximize your safety
when towing a trailer:
Have your exhaust system inspected for
leaks, and make necessary repairs before
starting on your trip.
Keep the rear-most windows closed.
CAUTION: (Continued)
CAUTION: (Continued)

If exhaust does come into your vehicle
through a window in the rear or another
opening, drive with your front, main
heating or cooling system on and with the
fan on any speed. This will bring fresh,
outside air into your vehicle. Do not use
the climate control setting for maximum air
because it only recirculates the air inside
your vehicle. SeeClimate Control System
(With Air Conditioning ) on page 3-25or
Climate Control System (Heater Only) on
page 3-27.
Towing a trailer requires a certain amount of experience.
Before setting out for the open road, you’ll want to get
to know your rig. Acquaint yourself with the feel of
handling and braking with the added weight of the trailer.
And always keep in mind that the vehicle you are
driving is now a good deal longer and not nearly as
responsive as your vehicle is by itself.
4-86

Engine Fan Noise
If your vehicle has a clutched engine cooling fan, when
the clutch is engaged, the fan spins faster to provide
more air to cool the engine. In most everyday driving
conditions, the fan is spinning slower and the clutch is
not fully engaged. This improves fuel economy and
reduces fan noise. Under heavy vehicle loading, trailer
towing, and/or high outside temperatures, the fan speed
increases as the clutch more fully engages, so you may
hear an increase in fan noise. This is normal and should
not be mistaken as the transmission slipping or making
extra shifts. It is merely the cooling system functioning
properly. The fan will slow down when additional cooling
is not required and the clutch disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch partially
disengages.
If your vehicle has electric cooling fans, you may hear
the fans spinning at low speed during most everyday
driving. The fans may turn off if no cooling is required.
Under heavy vehicle loading, trailer towing, and/or high
outside temperatures, or if you are operating your air
conditioning system, the fans may change to high speed
and you may hear an increase in fan noise.
This is normal and indicates that the cooling system is
functioning properly. The fans will change to low speed
when additional cooling is no longer required.
Power Steering Fluid
SeeEngine Compartment
Overview on page 5-14for
reservoir location.
When to Check Power Steering Fluid
It is not necessary to regularly check power steering uid
unless you suspect there is a leak in the system or you
hear an unusual noise. A uid loss in this system could
indicate a problem. Have the system inspected and
repaired.
5-39

Tire Terminology and Denitions
Air Pressure:The amount of air inside the
tire pressing outward on each square inch of the
tire. Air pressure is expressed in pounds per
square inch (psi) or kilopascal (kPa).
Accessory Weight
:This means the combined
weight of optional accessories. Some examples of
optional accessories are, automatic transmission,
power steering, power brakes, power windows,
power seats, and air conditioning.
Aspect Ratio
:The relationship of a tire’s height
to its width.
Belt
:A rubber coated layer of cords that is
located between the plies and the tread. Cords
may be made from steel or other reinforcing
materials.
Bead
:The tire bead contains steel wires wrapped
by steel cords that hold the tire onto the rim.
Bias Ply Tire
:A pneumatic tire in which the plies
are laid at alternate angles less than 90 degrees
to the centerline of the tread.Cold Tire Pressure
:The amount of air pressure
in a tire, measured in pounds per square inch
(psi) or kilopascals (kPa) before a tire has built up
heat from driving. SeeInflation - Tire Pressure
on page 5-74.
Curb Weight
:The weight of a motor vehicle with
standard and optional equipment including the
maximum capacity of fuel, oil, and coolant, but
without passengers and cargo.
DOT Markings
:A code molded into the sidewall
of a tire signifying that the tire is in compliance
with the U.S. Department of Transportation (DOT)
motor vehicle safety standards. The DOT code
includes the Tire Identication Number (TIN),
an alphanumeric designator which can also identify
the tire manufacturer, production plant, brand, and
date of production.
GVWR
:Gross Vehicle Weight Rating. See
Loading Your Vehicle on page 4-36.
GAWR FRT
:Gross Axle Weight Rating for
the front axle. SeeLoading Your Vehicle
on page 4-36.
5-71

Fuses Usage
1 Right Trailer Stop/Turn Lamp
2Electronic Suspension Control,
Automatic Level Control Exhaust
3 Left Trailer Stop/Turn Lamp
4 Engine Controls
5Engine Control Module, Throttle
Control
6 Trailer Brake Controller
Fuses Usage
7 Front Washer
8 Oxygen Sensor
9 Antilock Brakes System 2
10 Trailer Back-up Lamps
11 Driver Side Low-Beam Headlamp
12 Engine Control Module (Battery)
13Fuel Injectors, Ignition Coils
(Right Side)
14Transmission Control Module
(Battery)
15 Vehicle Back-up Lamps
16Passenger Side Low-Beam
Headlamp
17 Air Conditioning Compressor
18 Oxygen Sensors
19 Transmission Controls (Ignition)
20 Fuel Pump
21 Fuel System Control Module
22 Not Used
23 Not Used
24Fuel Injectors, Ignition Coils
(Left Side)
25 Trailer Park Lamps
26 Driver Side Park Lamps
5-127

J-Case Fuses Usage
57 Cooling Fan 1
58 Not Used
59 Heavy Duty Antilock Brake System
60 Cooling Fan 2
61 Antilock Brake System 1
62 Starter
63 Stud 2 (Trailer Brakes)
64 Left Bussed Electrical Center 1
65 Not Used
66 Heated Windshield Washer System
67 Four-Wheel Drive System
68Stud 1
(Trailer Connector Battery Power)
(Optional - 40A Fuse Required)
69 Mid-Bussed Electrical Center 1
70 Climate Control Blower
72 Not Used
73 Left Bussed Electrical Center 2Relays Usage
FAN HI Cooling Fan High Speed
FAN LO Cooling Fan Low Speed
ENG EXH VLV Not Used
FAN CNTRL Cooling Fan Control
HDLP LO/HID Low-Beam Headlamp
FOG LAMP Front Fog Lamps
A/C CMPRSR Air Conditioning Compressor
STRTR Starter
PWR/TRN Powertrain
FUEL PMP Fuel Pump
PRK LAMP Parking Lamps
REAR DEFOG Rear Defogger
RUN/CRANK Switched Power
5-129

Capacities and Specications
The following approximate capacities are given in English and metric conversions. SeeRecommended Fluids and
Lubricants on page 6-15for more information.
If your vehicle has the DURAMAX
®Diesel engine, see the DURAMAX®Diesel manual for more information.
ApplicationCapacities
English Metric
Air Conditioning Refrigerant R134aFor the air conditioning system refrigerant charge
amount, see the refrigerant caution label located
under the hood. See your dealer for more
information.
Cooling System
4.3L V6 ** 16.5 qt 15.6 L
4.8L V8 ** 16.9 qt 16.0 L
5.3L V8 ** 16.9 qt 16.0 L
6.0L V8 * 16.4 qt 15.5 L
6.0L V8 ** 16.8 qt 15.9 L
* 2500, 3500 series
** 1500 series
Engine Oil with Filter
4.3L V6 4.5 qt 4.3 L
4.8L V8; 5.3L V8; 6.0L V8 6.0 qt 5.7 L
Fuel Tank
1500 Series Standard and Short Box 26.0 gal 98.0 L
1500 Series Long Box 34.0 gal 128.7 L
5-130

Maintenance Footnotes (Gasoline
Engine)
This maintenance section applies to vehicles with a
gasoline engine. If your vehicle has a diesel engine, see
the maintenance schedule section in the DURAMAX
®
Diesel manual.
†The U.S. Environmental Protection Agency or the
California Air Resources Board has determined that the
failure to perform this maintenance item will not nullify
the emission warranty or limit recall liability prior to
the completion of the vehicle’s useful life. We, however,
urge that all recommended maintenance services be
performed at the indicated intervals and the
maintenance be recorded.
#Lubricate the front suspension, steering linkage, and
parking brake cable guides. Control arm ball joints
on 2500/3500 series vehicles require lubrication
but should not be lubricated unless their temperature is
10°F (−12°C) or higher, or they could be damaged.
Control arm ball joints on 1500 series vehicles are
maintenance-free. Vehicles used under severe
commercial operating conditions require lubrication on a
regular basis every 3,000 miles (5 000 km).(a)Visually inspect brake lines and hoses for proper
hook-up, binding, leaks, cracks, chafing, etc. Inspect
disc brake pads for wear and rotors for surface
condition. Inspect drum brake linings/shoes for wear or
cracks. Inspect other brake parts, including drums,
wheel cylinders, calipers, parking brake, etc.
(b)Visually inspect front and rear suspension and
steering system for damaged, loose or missing parts,
signs of wear or lack of lubrication. Inspect power
steering lines and hoses for proper hook-up, binding,
leaks, cracks, chafing, etc. Visually check constant
velocity joints, rubber boots, and axle seals for leaks.
(c)Visually inspect hoses and have them replaced
if they are cracked, swollen, or deteriorated. Inspect all
pipes, fittings and clamps; replace with genuine parts
as needed. To help ensure proper operation, a pressure
test of the cooling system and pressure cap and
cleaning the outside of the radiator and air conditioning
condenser is recommended at least once a year.
(d)Inspect wiper blades for wear, cracking, or
contamination. Clean the windshield and wiper blades, if
contaminated. Replace wiper blades that are worn or
damaged. See Windshield Wiper Blade Replacement on
page 5-65andWindshield and Wiper Blades on
page 5-117for more information.
6-9

Engine Drive Belt Routing
(A) Air Conditioning Compressor
If your vehicle has the DURAMAX
®®Diesel engine, see
the DURAMAX®®Diesel manual for more information. V6 Engines
V8 Engines
6-18