1999 GMC JIMMY air condition

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Temperature Knob
The middle knob on the control panel lets you select the
desired air temperature in your vehicle. This knob will
allow you to adjust the interior air temperature
independently of the function knob setting. Move the
knob clockwise toward 82 for warmer air. Move the
knob counterclockwise toward 66 for cooler air.
Full Hot: If you turn the temperature knob past 82
F
(28
C), the system will go into the ªfull hotº mode.
The system will remain at that maximum heating setting
and the fan will blow at the speed the fan knob is set to.
If the fan is in AUTO, it will run at full speed.
Full Cold: If you turn the temperature knob past 66
F
(19
C), the system will go into the ªfull coldº mode.
The system will remain at that maximum cooling setting
and the fan will blow at the speed the fan knob is set to.
If the fan is in AUTO, it will run at full speed.
Choosing either maximum setting will not cause the
system to heat or cool any faster.Mode Knob - Automatic Operation
The right knob on the control panel allows you to
choose the direction of air delivery. When the system is
set for automatic operation, sensors will control the air
delivery mode. Air will come primarily from the floor or
instrument panel outlets, with some air directed to the
windshield to prevent fogging.
When the system is in AUTO mode, the air conditioning
light will turn on, and the recirculation and outside air
lights turn off. With the system in full auto control (both
the fan and mode knobs in AUTO), you still have the
ability to override any function. However, continually
overriding the outside air or the A/C compressor will
limit the ability of the system to cool the
vehicle quickly.
If you push a button for a function which is not
available, the light next to that button will flash three
times to alert you that it's not available.
To find your comfort zone, start with the 74
F (23
C)
setting and allow about 20 minutes for the system to
adjust the temperature if necessary.

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With the automatic setting, the air conditioning
compressor automatically cycles when needed to cool
the air. In cold weather, when the system senses the need
for heat, the airflow will be directed out the floor
outlets. As the interior temperature approaches a desired
setting, the blower speed will decrease. To maintain
interior comfort, the airflow will adjust between the
instrument panel air outlets and floor outlets. On bright
sunny days in cool weather, the airflow may come out of
the air conditioning and floor outlets (bi
-level mode) to
maintain comfort and prevent stuffiness.
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 outside air
temperature, engine coolant temperature or the time
since the engine was last started. As the coolant warms
up, the blower fan speed will gradually increase and air
will flow from the heater outlets, with some airflow to
the windshield to prevent fogging under most
normal conditions.
If your vehicle is sitting out on a warm day and you
have the fan set on AUTO, the air will first flow out of
the floor air outlets for a few seconds. That is normal.
This is to expel hot air from the air outlets. As the air is
cooled, the airflow will move through the air
conditioning outlets.Be careful not to put anything over the solar sensor
located around the center of the instrument panel.
This sensor is used by the automatic system to
regulate temperature.
Mode Knob
- Manual Operation
The right knob on the control panel allows you to
choose the direction of air delivery.
You can choose to set the climate control system
operations yourself, or let the system work for you by
placing the system in AUTO mode. See ªMode
Knob
- Automatic Operationº earlier in this section.
PANEL: This setting directs most of the air
through the instrument panel outlets and a small amount
through the floor outlets.
BI-LEVEL: Air is delivered through the heater
floor outlets as well as the instrument panel outlets.
HEATER: This setting directs most of the
warmed air through the heater floor outlets and some air
through the windshield defroster outlets.

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BLEND: Airflow is divided equally between the
heater floor outlet and the windshield defroster outlets.
The air conditioning compressor may run to dehumidify
the air to prevent window fogging.
DEFROST: This setting directs most air through
the windshield defroster outlets and some through the
heater outlets. The air conditioning compressor may run
to dehumidify the air to prevent window fogging.
OUTSIDE AIR: Press this button to force the
system to use outside air. Press it again to close off the
outside air.
Pressing the OUTSIDE AIR button will cancel the
RECIRCULATION button.
RECIRCULATION: Press this button to limit
the amount of fresh air entering your vehicle. This is
helpful when you are trying to limit odors entering your
vehicle. In the AUTO mode, the system will use
recirculation as necessary to cool the air. Pressing the
recirculation button will change the operation to a
manual mode and the air will recirculate non
-stop. Press
this button again to turn off the recirculation feature.RECIRCULATION may be selected with the fan control
in OFF to limit odors, outside air and dust from entering
your vehicle.
Pressing the RECIRCULATION button will cancel the
OUTSIDE AIR button.
A/C: Press this button to turn the air conditioning
on and off. The system will cool and dehumidify the air
inside the vehicle when the A/C light is on.
Air conditioning will be automatically disabled when
the outside temperature drops below a level which air
conditioning is ineffective.
Remember that in order for the automatic system to perform
well, it needs A/C to provide cooling performance.

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3-7 Air Conditioning
On hot days, open the windows long enough to let hot
inside air escape. This reduces the time it takes for your
vehicle to cool down. Then keep your windows closed
for the air conditioner to work its best.
For quick cool
-down on very hot days, use MAX A/C
with the temperature knob turned to the left. This setting
should be used to keep odors and/or dust from entering
the vehicle. For normal cooling on hot days, use A/C
with the temperature knob turned to the left.
On vehicles equipped with the Electronic Climate
Control system, this same performance can be achieved
as long as the A/C is enabled and the outside air button
is not active.
On cool but sunny days, use BI
-LEVEL A/C to deliver
warm air to the floor and cooler air to the instrument
panel outlets.
When the air conditioner is on, you may sometimes
notice slight changes in your vehicle's engine speed and
power. This is normal because the system is designed
to cycle the compressor on and off to keep the
desired temperature.
Heating
The heater works best if you keep your windows closed
while using it. On cold days, use HEATER with the
temperature knob turned clockwise. BLEND is useful in
cool weather when you have fog or ice on the
windshield or side windows.
If you use the optional engine coolant heater before
starting your engine, your heating system will produce
warmer air faster to heat the passenger compartment in
cold weather. See ªEngine Coolant Heaterº in the Index.
Defogging and Defrosting
On cool, humid days, use BLEND to keep the
windshield and side windows clear.
Use DEFROST to remove fog or ice from the
windshield quickly in extreme humid or cold conditions.
Turn the temperature knob to the right and move the fan
control toward high.

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5-10 If No Steam Is Coming From Your Engine
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. See ªDriving on Gradesº in the Index.
If you get the overheat warning 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 window as necessary.
3. If you're in a traffic jam, shift to NEUTRAL (N);
otherwise, shift to the highest gear while
driving
-- DRIVE (D) or THIRD (3) 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 down the
accelerator until the engine speed is about twice as fast
as normal idle speed for at least three minutes while
you're parked. If you still have the warning, turn off
the 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.

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Engine Fan Noise
This 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 clutch is not engaged. This improves fuel
economy and reduces fan noise. Under heavy vehicle
loading, trailer towing and/or high outside temperatures,
the fan speed increases when the clutch 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 disengages.
If a Tire Goes Flat
It's unusual for a tire to ªblow outº 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 ªblowout,º here are a few
tips about what to expect and what to do:
If a front tire fails, 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.

6-
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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 Service
6
-3 Fuel
6
-5 Fuels in Foreign Countries
6
-5 Filling Your Tank
6
-7 Filling a Portable Fuel Container
6
-8 Checking Things Under the Hood
6
-10 Engine Oil
6
-15 Engine Air Cleaner/Filter
6
-16 Automatic Transmission Fluid
6
-19 Manual Transmission Fluid
6
-20 Hydraulic Clutch
6
-21 Rear Axle
6
-22 Four-Wheel Drive
6
-24 Radiator Pressure Cap
6
-24 Thermostat
6
-24 Engine Coolant
6
-27 Power Steering Fluid
6
-28 Windshield Washer Fluid6
-29 Brakes
6
-33 Battery
6
-34 Bulb Replacement
6
-39 Windshield Wiper Blade Replacement
6
-41 Tires
6
-49 Appearance Care
6
-50 Cleaning the Inside of Your Vehicle
6
-52 Care of Safety Belts
6
-53 Cleaning the Outside of Your Vehicle
6
-57 GM Vehicle Care/Appearance Materials
6
-58 Vehicle Identification Number (VIN)
6
-58 Service Parts Identification Label
6
-59 Electrical System
6
-65 Replacement Bulbs
6
-65 Capacities and Specifications
6
-66 Air Conditioning Refrigerants
6
-66 Normal Maintenance Replacement Parts

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If your vehicle is certified to meet California Emission
Standards (indicated on the underhood emission control
label), it is designed to operate on fuels that meet
California specifications. If such fuels are not available
in states adopting California emissions standards, your
vehicle will operate satisfactorily on fuels meeting
federal specifications, but emission control system
performance may be affected. The malfunction indicator
lamp on your instrument panel may turn on and/or your
vehicle may fail a smog
-check test. (See ªMalfunction
Indicator Lampº in the Index.) If this occurs, return to
your authorized GM dealer for diagnosis to determine
the cause of failure. In the event it is determined that the
cause of the condition is the type of fuels used, repairs
may not be covered by your warranty.
Some gasolines that are not reformulated for low
emissions may contain an octane
-enhancing additive
called methylcyclopentadienyl manganese tricarbonyl
(MMT); ask your service station operator whether or not
the fuel contains MMT. General Motors does not
recommend the use of such gasolines. If fuels containing
MMT are used, spark plug life may be reduced and your
emission control system performance may be affected.
The malfunction indicator lamp on your instrument
panel may turn on. If this occurs, return to your
authorized GM dealer for service.To provide cleaner air, all gasolines in the United States
are now required to contain additives that will help
prevent deposits from forming in your engine and fuel
system, allowing your emission control system to
function properly. Therefore, you should not have to add
anything to the fuel. In addition, gasolines containing
oxygenates, such as ethers and ethanol, and
reformulated gasolines may be available in your area to
contribute to clean air. General Motors recommends that
you use these gasolines, particularly if they comply with
the specifications described earlier.
NOTICE:
Your vehicle was not designed for fuel that
contains methanol. Don't use it. It can corrode
metal parts in your fuel system and also damage
plastic and rubber parts. That damage wouldn't
be covered under your warranty.