1998 GMC SIERRA air condition

Mode Knob
The right knob on the control panel allows you to
choose the direction
of air delivery. The control knob
can be placed in any position between two mode settings
to blend the flow of air.
+e
/$ VENT This setting directs air through the
instrument panel outlets.
+’ VENT/HEAT Use this setting to divide airflow
between the floor outlets and instrument panel outlets.
+’ HEATER: This setting directs air through the
+e
0
heater floor outlets.
+’ DEFOG: This setting directs air to the heater
we
outlets and toward the windshield.
DEFROST This setting directs air toward the
windshield.
Air Conditioning
On hot days, open the windows long enough to let hot
air inside escape. This reduces the titne
it takes for your
vehicle to cool down. Then keep your windows closed
for the air conditioner to work its best. The recirculation button, between the
fan and
temperature
knobs, allows the air inside your vehicle to
be recirculated. This setting helps to maximize your air
conditioner’s performance and your vehicle’s fuel
economy. This setting also cools the air the fatest and
can be used
to keep unwanted odors and/or dust from
entering the vehicle. When using the air conditioner,
turn off recirculation after the vehicle reaches
a
comfortable interior temperature. When the right knob
on the control panel is between HEATER and
DEFROST, the recirculation feature will not function.
The A/C button, between the temperature and mode
knobs, allows the air coming into your vehicle to be
cooled. This setting is useful for normal cooling on hot
days. When you use
A/C with the recirculation button
pushed
in, turn off recirculation as soon as the vehicle
reaches
a comfortable interior temperature.
With the A/C
on, move the temperature knob to MAX
for maximum cooling. This setting also puts the system
in the recirculation mode and helps to maximize your air
conditioner‘s performance and your vehicle’s fuel
economy. This setting also cools the air the Fdstest. After
the vehicle‘s interior reaches
a comfortable temperature,
move the temperature knob to the right, to place the air
conditioning system
in the normal mode.
3-4
ProCarManuals.com

Heating
The heater works best if you keep your windows closed
while using it. On cold days, use the
HEATER or
VENTMEAT setting with the temperature knob in the
red area.
If you use the engine coolant heater before starting your
engine in cold weather,
20” F (-8 O C) or lower, your
heating system will produce warmer air faster, to heat
the passenger compartment
in cold weather.
The use of an engine coolant heater also reduces the
time it takes for the engine to reach normal operating
temperature, and shortens the time it takes the heater to
reach full output. For more information, see “Engine
Coolant Heater” in the Index.
Ventilation System
For mild outside temperatures when little heating or
cooling is needed,
use VENT to direct outside air
through your vehicle. Air will flow through the
instrument panel outlets.
Your vehicle’s ventilation system supplies outside
air to
the inside of your vehicle when
it is moving. With the side
windows closed,
air will flow into the front air inlet grilles,
through the vehicle, and out the
air exhaust valves. Outside air
will also enter the vehicle when the heater or
the air conditioning fan is running, unless you have the
recirculation button pushed in. For more information on
the recirculation button, see “Air Conditioning’’ earlier
in this section.
Your vehicle has air outlets in the center and
on the sides
of your instrument panel. You can move the outlets from
side-to-side or up and down to direct the flow of air, or
close the outlets altogether. When you close an outlet,
it
will increase the flow of air coming out of any outlets
that are open. These outlets do not completely shut off
airflow when in the closed position.
ProCarManuals.com

Ventilation Tips
0
0
0
0
Keep the hood and front air inlet 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, turn the
blower fan to
HI for a few moments before driving.
This helps clear the intake ducts of snow and
moisture, and reduces the chance of fogging the
inside of your windows.
Keep
the air path under the front seats clear of
objects. This helps air
to circulate throughout
your vehicle.
The use of hood air deflectors may adversely
affect
the performance of the heating and air
conditioning system.
Defogging and Defrosting
On cool, humid days, use DEFOG to keep the
windshield and side windows clear. Use
DEFROST to
remove fog
or ice from the windshield in extremely
humid or cold conditions. Use DEFROST with the
temperature knob toward the red area and the fan control
toward
HI.
Rear Window Defogger (If Equipped)
If you see lines running across the rear window, you
have
a rear window defogger. The lines warm the glass.
To turn on the rear window
defogger, press this button
next to the fan control knob.
The rear window defogger will only work if the
ignition switch is turned to
RUN. For best results, clear
the window of as much
snow or ice
as possible first.
The defogger
will shut itself off after several minutes. If
you need additional warming time, press the button
again.
You can turn the defogger off at any time by
pressing the button.
Do not attach a temporary vehicle license, tape or decals
across the defogger grid on the rear window.
ProCarManuals.com

2. Get the vehicles close enough so the jumper cables
can reach, but be sure the vehicles aren’t touching
each other. If they are, it could cause a ground
connection
you don’t want. You wouldn’t be able
to start your vehicle, and the bad grounding could
damage the electrical systems.
To avoid the possibility
of the vehicles rolling, set
the parking brake firmly on both vehicles involved
in the jump start procedure. Put an automatic
transmission in
PARK (P) or a manual transmission
in NEUTRAL (N).
If you have a four-wheel-drive
vehicle, be sure the transfer case is not in
NEUTRAL
(N).
3. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or accessory power outlets. Turn
off all lamps
that aren’t needed as well as radios. This will avoid
sparks and help save both batteries. In addition, it
could save your radio!
I NOTICE:
If you leave your radio on, it could be badly
damaged. The repairs wouldn’t be covered by
your warranty.
4. Open the hoods and locate the batteries. Find the
positive
(+) and negative (-) terminals on each battery.
If your vehicle has air conditioning, the auxiliary
electric fan under the hood can start up even
when the engine is not running and can injure
you. Keep hands, clothing and tools
away from
any underhood electric fan.
5-4
t
ProCarManuals.com

If you get the overheat warning with no sign of steam,
try this for
a minute or so:
1. If you have an air conditioner, turn it off.
2. Turn on your heater to full hot at the highest fan
speed and open the window
as necessary.
3. If you’re in a traffic jam, shift to NEUTRAL (N);
otherwise, shift to the highest gear while
driving
-- AUTOMATIC OVERDRIVE (@)
for automatic transmissions.
If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about
10 minutes.
If the warning doesn’t come back on, you can
drive normally.
If the warning continues, pull over, stop, and park your
vehicle right away.
If there’s still no sign
of steam, push the accelerator until
the engine speed
is about twice as fdst as normal idle
speed. Bring the engine speed back to normal idle speed
after two or three minutes. Now see if the warning stops.
But then, if you still have the warning, turn ofthe
engine
and get everyone out of the vehicle until it
cools down.
You may decide not to lift the hood but to get service
help right away.
Cooling System -- Gasoline Engines
When you decide it’s safe to lift the hood, here’s what
you’ll see:
A. Coolant Recovery Tank
B. Radiator Pressure Cap
C. Engine Fan(s)
5-15
ProCarManuals.com

If your vehicle has air conditioning, the auxiliary
electric engine cooling fan under the hood can
start up even when the engine is not running and
can injure you. Keep hands, clothing and tools
away from any underhood electric fan.
If the coolant inside the coolant recovery tank is boiling,
don’t do anything else until it cools down. The
codant level should be at or above the
COLD mark.
If it isn’t, you may have a leak in the radiator hoses,
heater hoses, radiator, water pump or somewhere else
in
the cooling system.
Heater and radiator hoses, and other engine
parts, can be very hot. Don’t touch them.
If you
do, you can be burned.
Don’t run the engine if there is a leak.
If you run
the engine, it could lose all coolant. That could
cause an engine fire, and
you could be burned.
Get any leak fixed before you drive the vehicle.
NOTICE:
Engine damage from running your engine
without coolant isn’t covered by your warranty.
ProCarManuals.com

Engine Fan Noise If a Tire Goes Flat
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. It‘s
unusual for
a tire to “blow out’’ while you’re driving,
especially if you maintain your tires properly.
If air goes
out of a tire, it’s 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 hils, the flat tire will create a drag that
pulls the vehicle toward that side. Take your foot off the
accelerator pedal and grip the steering wheel firmly.
Steer to maintain lane position, and then gently brake to
a stop well out of the traffic lane.
A rear blowout, particularly on a curve, acts much like a
skid and may require the same correction you’d use in
a skid. In any rear blowout, remove your foot from
the accelerator pedal. Get
the vehicle under control by
steering the way you want the vehicle to go.
It may be
very bumpy and noisy, but you can still steer. Gently
brake to
a stop -- well off the road if possible.
If a tire goes flat, the next part shows how to use your
jacking equipment to change a flat tire safely.
5-23
ProCarManuals.com

Section 6 Service and Appearance Care
Here you will find information about the care of your vehicle. This section begins with service and fuel information,
and then it shows how to check important fluid and lubricant levels. There is also technical information about your
vehicle, and
a part devoted to its appearance care.
6-2
6-3
6-5
6-6
6- 8
6-9
6- 13
6- 14
6-18
6-2
I
6-24
6- 25
6-26
6-26
6-28 6-32
6-32 Service
Fuel (Gasoline Engine)
Fuels
in Foreign Countries (Gasoline Engines)
Filling Your Tank (Gasoline Engine)
Filling a Portable Fuel Container
Checking Things Under the Hood
Noise Control System
Engine Oil (Gasoline Engine)
Air Cleaner Filter (Gasoline Engine)
Automatic Transmission Fluid
Manual Transmission Fluid
Hydraulic Clutch
Rear Axle
Four-wheel Drive
Engine Coolant Radiator Pressure Cap (Gasoline Engine)
Thermostat
, 6-33
6-3 3
6-35
6-39
6-39
6-50
6-5
1
6-6 1
6-62
6-65 6-69
6-70
6-70
' 6-76
6-77 6-79 Power
Steering Fluid
Windshield Washer Fluid
Brakes
Battery
Bulb Replacement
Windshield Wiper Blade Replacement
Tires
Appearance Care
Cleaning the Inside
of Your Vehicle
Cleaning the Outside of Your Vehicle
Appearance Care Materials Chart
Vehicle Identification Number (VIN)
Electrical System Replacement
Bulbs
Capacities and Specifications
Air Conditioning Refrigerants
6-1
ProCarManuals.com