2008 JEEP GRAND CHEROKEE air condition

Air flows through the registers in the back of the
center console, and under the front seats to the rear
seat passengers. These registers can be closed to block
airflow. The center console outlets deliver conditioned
air while the floor outlets deliver heated air.
²Panel
Air flows through the outlets located in the in-
strument panel. Air flows through the registers in
the back of the center console to the rear seat passen-
gers. These registers can be closed to block airflow.
Depress this button to turn on and off the air
conditioning during manual operation only. Con-
ditioned outside air is then directed through the
outlets selected on the mode control dial. The button
includes an LED that illuminates when manual operation
is selected.
NOTE:To manually control the air conditioning the
mode selector must be moved out of the AUTO position.This button can be used to block out smoke,
odors, dust, high humidity, or if rapid cooling
is desired. The recirculation mode should only
be used temporarily. The button includes an
LED that illuminates, which indicates that the recircula-
tion mode is active. You may use this feature separately.
NOTE:Extended use of recirculation may cause the
windows to fog. If the interior of the windows begins to
fog, press the ªRecirculateº icon button to return to
outside air. Some temp./humidity conditions will cause
captured interior air to condense on windows and ham-
per visibility. For this reason, the system will not allow
ªRecirculateº to be selected while in the defrost or
defrost/floor modes. Attempting to use the recirculation
while in these modes will cause the LED in the button to
blink and then turn off.
UNDERSTANDING YOUR INSTRUMENT PANEL 235
4

Operating Tips
Window Fogging
Windows will fog on the inside when the humidity inside
the vehicle is high. This often occurs in mild or cool
temperatures when it's rainy or humid. In most cases
turning on the Air-conditioning (pressing the snowflake
button) will clear the fog. Adjust the temperature control,
air direction and blower speed to maintain comfort.
As the temperature gets colder it may be necessary to
direct air onto the windshield. Adjust the temperature
control and blower speed to maintain comfort. Higher
blower speeds will reduce fogging. Interior fogging on
the windshield can be quickly removed by selecting the
defrost mode.
Regular cleaning of the inside of the windows with a
non-filming cleaning solution (vinegar and water works
very well) will help prevent contaminates (cigarettesmoke, perfumes, etc.) from sticking to the windows.
Contaminates increase the rate of window fogging.Summer Operation
Air conditioned vehicles must be protected with a high
quality antifreeze coolant during summer to provide
proper corrosion protection and to raise the boiling point
of the coolant for protection against overheating. A 50 %
concentration is recommended. Refer to Recommended
Fluids and Genuine Parts for the proper coolant type.
When using the air conditioner in extremely heavy traffic
in hot weather especially when towing a trailer, addi-
tional engine cooling may be required. If this situation is
encountered, operate the transmission in a lower gear to
increase engine RPM, coolant flow and fan speed. When
stopped in heavy traffic, it may be necessary to shift into
N (Neutral) and depress the accelerator slightly for fast
idle operation to increase coolant flow and fan speed.
236 UNDERSTANDING YOUR INSTRUMENT PANEL

Your air conditioning system is also equipped with an
automatic recirculation system. When the system senses
a heavy load or high heat conditions, it may use partial
Recirculation A/C mode to provide additional comfort.
Winter Operation
When operating the system during the winter months,
make sure the air intake, located directly in front of the
windshield, is free of ice, slush, snow, or other obstruc-
tions.
Vacation Storage
Anytime you store your vehicle, or keep it out of service
(i.e. vacation) for two weeks or more, run the air condi-
tioning system at idle for about five minutes in the fresh
air and high blower setting. This will insure adequate
system lubrication to minimize the possibility of com-
pressor damage when the system is started again.
UNDERSTANDING YOUR INSTRUMENT PANEL 237
4

Check tire pressures more often if subject to a wide range
of outdoor temperatures, as tire pressures vary with
temperature changes.
Tire pressures change by approximately 1 psi (7 kPa) per
12É F (7É C) of air temperature change. Keep this in mind
when checking tire pressure inside a garage especially in
the winter.
Example: If garage temperature = 68É F (20É C) and the
outside temperature = 32É F (0É C) then the cold tire
inflation pressure should be increased by 3 psi (21 kPa),
which equals 1 psi (7 kPa) for every 12É F (7É C) for this
outside temperature condition.
Tire pressure may increase from 2 to 6 psi (13 to 40 kPa)
during operation. DO NOT reduce this normal pressure
build up or your tire pressure will be too low.Tire Pressures for High Speed Operation
The manufacturer advocates driving at safe speeds
within posted speed limits. Where speed limits or condi-
tions are such that the vehicle can be driven at high
speeds, maintaining correct tire inflation pressure is very
important. Increased tire pressure and reduced vehicle
loading may be required for high speed vehicle opera-
tion. Refer to original equipment or an authorized tire
dealer for recommended safe operating speeds, loading
and cold tire inflation pressures.
WARNING!
High speed driving with your vehicle under maxi-
mum load is dangerous. The added strain on your
tires could cause them to fail. You could have a
serious accident. Don't drive a vehicle loaded to the
maximum capacity at continuous speeds above 75
mph (120 km/h).
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Radial-Ply Tires
WARNING!
Combining radial ply tires with other types of tires
on your vehicle will cause your vehicle to handle
poorly. The instability could cause an accident. Al-
ways use radial tires in sets of four. Never combine
them with other types of tires.
Cuts and punctures in radial tires are repairable only in
the tread area because of sidewall flexing. Consult your
dealer for radial tire repairs.
Tire Spinning
When stuck in mud, sand, snow, or ice conditions, do not
spin your vehicle's wheels above 35 mph (55 km/h).
WARNING!
Fast spinning tires can be dangerous. Forces gener-
ated by excessive wheel speeds may cause tire dam-
age or failure. A tire could explode and injure some-
one. Do not spin your vehicle's wheels faster than 35
mph (55 km/h) when you are stuck, and do not let
anyone near a spinning wheel no matter what the
speed.
STARTING AND OPERATING 271
5

manufacturer. While MTBE is an oxygenate made from
Methanol, it does not have the negative effects of Metha-
nol.
MMT In Gasoline
MMT is a manganese containing metallic additive that is
blended into some gasoline to increase octane. Gasoline
blended with MMT provides no performance advantage
beyond gasoline of the same octane number without
MMT. Gasoline blended with MMT reduces spark plug
life and reduces emission system performance in some
vehicles. The manufacturer recommends that gasoline
without MMT be used in your vehicle. The MMT content
of gasoline may not be indicated on the gasoline pump;
therefore, you should ask your gasoline retailer whether
his/her gasoline contains MMT. It is even more impor-
tant to look for gasolines without MMT in Canada,
because MMT can be used at levels higher than those
allowed in the United States. MMT is prohibited in
Federal and California reformulated gasoline.
Materials Added to Fuel
All gasoline sold in the United States is required to
contain effective detergent additives. Use of additional
detergents or other additives is not needed under normal
conditions and they would result in additional cost.
Therefore, you should not have to add anything to the
fuel.
Fuel System Cautions
CAUTION!
Follow these guidelines to maintain your vehicle's
performance:
²The use of leaded gas is prohibited by Federal law.
Using leaded gasoline can impair engine performance,
and damage the emission control system.
280 STARTING AND OPERATING

²Guard against carbon monoxide with proper mainte-
nance. Have the exhaust system inspected every time
the vehicle is raised. Have any abnormal conditions
repaired promptly. Until repaired, drive with all side
windows fully open.
²Keep the trunk closed when driving your vehicle to
prevent carbon monoxide and other poisonous ex-
haust gases from entering the vehicle.
ADDING FUEL
Fuel Filler Cap (Gas Cap)
The gas cap is located behind the fuel filler door, on the
driver's side of the vehicle. If the gas cap is lost or
damaged, be sure the replacement cap is for use with this
vehicle.Fuel Filler Cap Location
282 STARTING AND OPERATING

Towing Tips Ð Electronic Speed Control (If
Equipped)
þ
Don't use in hilly terrain or with heavy loads.
þWhen using the speed control, if you experience speed
drops greater than 10 mph (16 km/h), disengage until
you can get back to cruising speed.
þUse speed control in flat terrain and with light loads to
maximize fuel efficiency.
Towing Tips Ð Cooling System
To reduce potential for engine and transmission over-
heating, take the following actions:
þCity Driving
When stopped for short periods of time, put transmission
in neutral and increase engine idle speed.
þHighway Driving
Reduce speed.
þAir Conditioning
Turn off temporarily.
þrefer to Cooling System Operating information in the
Maintenance section of this manual for more informa-
tion.
RECREATIONAL TOWING (BEHIND
MOTORHOME, ETC.)
Recreational towing is not allowed.
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