2007 GMC SIERRA CLASSIC air condition

If No Steam Is Coming From Your
Engine
The ENGINE COOLANT HOT message, along
with a low coolant condition, can indicate a serious
problem.
If you get an engine overheat warning, but see or
hear no steam, the problem may not be too
serious. Sometimes the engine can get a little too
hot when you:
Climb a long hill on a hot day.
Stop after high-speed driving.
Idle for long periods in traffic.
Tow a trailer. SeeTowing a Trailer on
page 429.
If you get the ENGINE COOLANT HOT message
with no sign of steam, try this for a minute or so:
1. If your air conditioner is on, turn it off.
2. Turn on your heater to full hot at the highest
fan speed and open the windows as
necessary.
3. If you are in a traffic jam, shift to
NEUTRAL (N); otherwise, shift to the highest
gear while driving — DRIVE (D) or THIRD (3).If you no longer have the overheat warning, you
can drive. Just to be safe, drive slower for
about 10 minutes. If the warning does not come
back on, you can drive normally.
If the warning continues, pull over, stop, park, and
fast idle your vehicle right away.
If there is still no sign of steam and your vehicle
is equipped with an engine-driven cooling fan,
push down the accelerator until the engine speed
is about twice as fast as normal idle speed for
at least three minutes while you are parked.
If there is still no sign of steam and your vehicle is
equipped with an electric engine cooling fan, idle
the engine for three minutes while you are parked.
If you still have the warning, turn off the engine
and get everyone out of the vehicle until it
cools down. Also, see “Overheated Engine
Protection Operating Mode” later in this section.
You may decide not to lift the hood but to get
service help right away.
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Overheated Engine Protection
Operating Mode (V8 Engines Only)
If an overheated engine condition exists and
the REDUCED ENGINE POWER message
is displayed, an overheat protection mode which
alternates ring groups of cylinders helps
prevent engine damage. In this mode, you will
notice a loss in power and engine performance.
This operating mode allows your vehicle to
be driven to a safe place in an emergency. Driving
extended miles (km) and/or towing a trailer in
the overheat protection mode should be avoided.
Notice:After driving in the overheated
engine protection operating mode, to avoid
engine damage, allow the engine to cool before
attempting any repair. The engine oil will be
severely degraded. Repair the cause of coolant
loss, change the oil and reset the oil life
system. SeeEngine Oil (Gasoline Engine) on
page 486.
Cooling System
When you decide it is safe to lift the hood, here is
what you will see:
A. Coolant Surge Tank
B. Coolant Surge Tank Pressure Cap
C. Engine Cooling Fan
8.1L V8 Engines
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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.
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Brake Wear
Your vehicle has front disc brakes and may have
rear drum brakes or rear disc brakes.
Disc brake pads have built-in wear indicators that
make a high-pitched warning sound when the
brake pads are worn and new pads are needed.
The sound may come and go or be heard all
the time your vehicle is moving, except when you
are pushing on the brake pedal rmly.
{CAUTION:
The brake wear warning sound means that
soon your brakes will not work well. That
could lead to an accident. When you hear
the brake wear warning sound, have your
vehicle serviced.
Notice:Continuing to drive with worn-out
brake pads could result in costly brake repair.
Some driving conditions or climates may cause
a brake squeal when the brakes are rst applied or
lightly applied. This does not mean something is
wrong with your brakes.Properly torqued wheel nuts are necessary to help
prevent brake pulsation. When tires are rotated,
inspect brake pads for wear and evenly tighten
wheel nuts in the proper sequence to GM torque
specications.
If you have rear drum brakes, they do not have
wear indicators, but if you ever hear a rear brake
rubbing noise, have the rear brake linings
inspected immediately. Rear brake drums should
be removed and inspected each time the tires
are removed for rotation or changing. Drum brakes
have an inspection hole to inspect lining wear
during scheduled maintenance. When you have
the front brake pads replaced, have the rear
brakes inspected, too.
Brake linings should always be replaced as
complete axle sets.
Brake Pedal Travel
See your dealer if the brake pedal does not return
to normal height, or if there is a rapid increase in
pedal travel. This could be a sign of brake trouble.
Brake Adjustment
Every time you make a brake stop, your brakes
adjust for wear.
519

(C) Aspect Ratio:A two-digit number that
indicates the tire height-to-width measurements.
For example, if the tire size aspect ratio is 75, as
shown in item C of the light truck (LT-Metric) tire
illustration, it would mean that the tire’s sidewall is
75 percent as high as it is wide.
(D) Construction Code:A letter code is used to
indicate the type of ply construction in the tire.
The letter R means radial ply construction;
the letter D means diagonal or bias ply
construction; and the letter B means belted-bias
ply construction.
(E) Rim Diameter:Diameter of the wheel in
inches.
(F) Service Description:The service description
indicates the load range and speed rating of a
tire. The load index can range from 1 to 279.
Speed ratings range from A to Z.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/
transaxle, 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.
548

Temperature – A, B, C
The temperature grades are A (the highest), B,
and C, representing the tire’s resistance to the
generation of heat and its ability to dissipate heat
when tested under controlled conditions on a
specied indoor laboratory test wheel. Sustained
high temperature can cause the material of the tire
to degenerate and reduce tire life, and excessive
temperature can lead to sudden tire failure. The
grade C corresponds to a level of performance
which all passenger car tires must meet under the
Federal Motor Vehicle Safety Standard No. 109.
Grades B and A represent higher levels of
performance on the laboratory test wheel than
the minimum required by law.
Warning:The temperature grade for this tire is
established for a tire that is properly inated
and not overloaded. Excessive speed,
underination, or excessive loading, either
separately or in combination, can cause heat
buildup and possible tire failure.
Wheel Alignment and Tire Balance
The tires and wheels on your vehicle were aligned
and balanced carefully at the factory to give you
the longest tire life and best overall performance.
Adjustments to wheel alignment and tire
balancing will not be necessary on a regular basis.
However, if you notice unusual tire wear or your
vehicle pulling to one side or the other, the
alignment may need to be checked. If you notice
your vehicle vibrating when driving on a smooth
road, your tires and wheels may need to be
rebalanced. See your dealer for proper diagnosis.
Wheel Replacement
Replace any wheel that is bent, cracked, or badly
rusted or corroded. If wheel nuts keep coming
loose, the wheel, wheel bolts and wheel nuts
should be replaced. If the wheel leaks air, replace
it (except some aluminum wheels, which can
sometimes be repaired). See your dealer if any of
these conditions exist.
Your dealer will know the kind of wheel you need.
560

CAUTION: (Continued)
Use another type of traction device
only if its manufacturer recommends
it for use on your vehicle and tire size
combination and road conditions. Follow
that manufacturer’s instructions. To help
avoid damage to your vehicle, drive
slowly, readjust or remove the device if it
is contacting your vehicle, and do not
spin your vehicle’s wheels.
If you do nd traction devices that will t,
install them on the rear tires.
Notice:If your vehicle does not have dual
wheels and is equipped with a tire size other
than P265/75R16, LT265/75R16, P265/70R17
or P275/55R20, use tire chains only where legal
and only when you must. Use chains that
are the proper size for your tires. Install them
on the tires of the rear axle. Don’t use
chains on the tires of the front axle.Tighten them as tightly as possible with the
ends securely fastened. Drive slowly and follow
the chain manufacturer’s instructions. If you
can hear the chains contacting your vehicle,
stop and retighten them. If the contact
continues, slow down until it stops. Driving
too fast or spinning the wheels with chains on
will damage your vehicle.
If a Tire Goes Flat
It is unusual for a tire to blowout while you are
driving, especially if you maintain your vehicle’s
tires properly. If air goes out of a tire, it is
much more likely to leak out slowly. But if you
should ever have a blowout, here are a few tips
about what to expect and what to do:
If a front tire fails, the at tire will create a drag
that pulls the vehicle toward that side. Take
your foot off the accelerator pedal and grip the
steering wheel rmly. Steer to maintain lane
position, and then gently brake to a stop well out
of the traffic lane.
563

Finish Damage
Any stone chips, fractures or deep scratches in
the nish should be repaired right away. Bare
metal will corrode quickly and may develop into
major repair expense.
Minor chips and scratches can be repaired with
touch-up materials available from your GM dealer.
Larger areas of nish damage can be corrected
in your GM dealer’s body and paint shop.
Underbody Maintenance
Chemicals used for ice and snow removal and
dust control can collect on the underbody. If these
are not removed, corrosion and rust can develop
on the underbody parts such as fuel lines,
frame, oor pan, and exhaust system even though
they have corrosion protection.
At least every spring, ush these materials from the
underbody with plain water. Clean any areas where
mud and debris can collect. Dirt packed in close
areas of the frame should be loosened before being
ushed. Your dealer or an underbody car washing
system can do this for you.
Chemical Paint Spotting
Some weather and atmospheric conditions can
create a chemical fallout. Airborne pollutants can
fall upon and attack painted surfaces on the
vehicle. This damage can take two forms: blotchy,
ring-shaped discolorations, and small, irregular
dark spots etched into the paint surface.
Although no defect in the paint job causes this, GM
will repair, at no charge to the owner, the surfaces
of new vehicles damaged by this fallout condition
within 12 months or 12,000 miles (20 000 km) of
purchase, whichever occurs rst.
596