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Air Conditioning and Heating Operation
To turn on the Air Conditioning, set the fan control at any
speed and press the snowflake button located on the
control panel. Conditioned air will be directed through
the outlets selected by the mode control. A light in the
snowflake button shows that the air conditioning is on.
Press the button a second time to turn the air condition-
ing off.
A/C Pushbutton
With the fan control in the ON posi-
tion, pushing the A/C button turns on
the air conditioning compressor. An
indicator light on the button shows
that the Air Conditioning compressor
is on. Conditioned air is now directed
through the mode outlets selected.
Pushing the button a second time turns the compressor
OFF.
Recirculation Pushbutton
Pushing the Recirculation button al-
lows interior air to recirculate continu-
ously in any position except defrost
and defrost/floor mode for rapid cool
down of the interior. See ªFast
Cooldownº later in this section.
Mode Control
The mode control allows you to
choose from several patterns of air
distribution.
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4
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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 by using MIX Mode
position on the control. 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. For proper coolant type,
refer to ªRecommended Fluids and Genuine Partsº in
Section 7.
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
NEUTRAL and depress the accelerator slightly for fast
idle operation to increase coolant flow and fan speed.
UNDERSTANDING YOUR INSTRUMENT PANEL 269
4
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NEUTRAL
Shift to Neutral when the vehicle is standing for pro-
longed periods with the engine running. The engine may
be started in this range. Set the parking brake if you must
leave the vehicle.
DRIVE
This position provides all forward gears, including 3rd
gear direct and 4th or 5th gear overdrive (see Overdrive
Operation). Use this range for most city and highway
driving.
SECOND
Use this position for driving slowly in heavy city traffic
or on mountain roads where more precise speed control
is desirable. Use it also when climbing long grades, and
for engine braking when descending moderately steep
grades. To prevent excessive engine speed do not exceed
45 mph (72 km/h) in this range.FIRST
Use this position for driving up very steep hills and for
engine braking at low speeds 20 mph (32 km/h) or less
when going downhill. To prevent excessive engine speed,
do not exceed 25 mph (40 km/h) in this range.
NOTE:Use caution when operating a heavily loaded
vehicle in SECOND or FIRST gear selections in high
ambients as torque converter slip can impose significant
additional heat load on the cooling system.
Overdrive Operation
The overdrive automatic transmission contains an elec-
tronically controlled fourth and fifth (if equipped) speed
(Overdrive). The transmission will automatically shift
from DRIVE to Overdrive if the following conditions are
present:
²the transmission selector is in DRIVE;
STARTING AND OPERATING 285
5
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When To Use ªTOW HAULº and ªO/D OFFº
Modes
When driving in hilly areas, towing a trailer, carrying a
heavy load, etc., and frequent transmission shifting oc-
curs, press the ªTOW HAUL O/D OFFº button once to
select TOW HAUL. This will improve performance andreduce the potential for transmission overheating or
failure due to excessive shifting. When operating in
ªTOW HAULº mode, 5th gear (if equipped) is disabled
and 2-3 and 3-4 shift patterns are modified. Shifts into
Overdrive (4th gear) are allowed during steady cruise
(for improved fuel economy) and automatic closed-
throttle downshifts to 3rd gear are performed (for im-
proved braking) when driving conditions warrant. Press-
ing the ªTOW HAUL O/D OFFº button a second time to
select O/D OFF will disable 4th and 5th gear completely,
which should eliminate any excessive transmission shift-
ing.
The ªTOW HAULº or ªO/D OFFº light will illuminate in
the instrument cluster to indicate when the switch has
been activated. Pressing the switch a third time restores
normal operation. If the ªTOW HAULº or ªO/D OFFº
modes are desired, the button must be pressed each time
the engine is started.
Tow Haul O/D Off Switch
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Fully depress the clutch pedal before shifting gears. As
you release the clutch pedal, lightly depress the accelera-
tor pedal.
2500 and 3500 models are equipped with the G56 manual
transmission. This transmission has a ªcreeperº 1st gear
which should be used to start from a standing position
when carrying a payload or towing a trailer. Damage to
the clutch can result from starting in 2nd or 3rd gear with
a loaded vehicle. An unloaded vehicle may be launched
in 2nd gear. Use each gear in numerical order ± do not
skip a gear.Recommended Vehicle Shift Speeds
To utilize your manual transmission efficiently for both
fuel economy and performance, it should be upshifted as
listed in recommended shift speed chart. Shift at the
vehicle speeds listed for acceleration. When heavily
loaded or pulling a trailer these recommended up-shift
speeds may not apply.
Maximum Recommended Up-shift Speeds
En-
gineModel L to 2 2 to 3 3 to 4 4 to 5 5 to 6
5.7L2500/
350015
mph
(24
km/h)25
mph
(40
km/h)40
mph
(64
km/h)45
mph
(72
km/h)50
mph
(81
km/h)
290 STARTING AND OPERATING
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Shifting Ð 1500 Vehicles
1500 models are equipped with a G238 manual transmis-
sion. This transmission has a clutch interlocking ignition
system. The clutch pedal must be fully depressed to start
the vehicle.Fully depress the clutch pedal before shifting gears. As
you release the clutch pedal, lightly depress the accelera-
tor pedal.
You should always use 1st gear when starting from a
standing position.
Recommended Shift Speeds
To utilize your manual transmission efficiently for both
fuel economy and performance, it should be upshifted as
listed in recommended shift speed chart. Shift at the
vehicle speeds listed for acceleration. When heavily
loaded or pulling a trailer these recommended up-shift
speeds may not apply.
Shift Pattern (1500 Models)
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Higher upshift speeds may be used to obtain a desired
acceleration rate.
6 Speed Manual Transmission Shift Speed in mph
(km/h)
En-
gineModel AxleAccel-
eration
Rate1to
22to
33to
44to
55to
6
3.7L ALL ALLACCEL
&
CRUISE15
(24)
10
(16)24
(39)
19
(31)34
(55)
27
(44)47
(76)
37
(60)56
(90)
41
(66)
4.7L All ALLACCEL
&
CRUISE15
(24)25
(40)40
(65)45
(72)50
(81)
Downshifting ± All Manual Transmissions
Moving from a high gear down to a lower gear is
recommended to preserve brakes when driving down
steep hills. In addition, downshifting at the right time
provides better acceleration when you desire to resume
speed. Downshift progressively. Do not skip gears to
avoid overspeeding the engine and clutch.
WARNING!
Do not downshift for additional engine braking on a
slippery surface. The drive wheels could lose their
grip and the vehicle could skid.
292 STARTING AND OPERATING
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This Electronically Shifted transfer case provides 5 mode
positions: 2-wheel drive (2WD), 4WD AUTO, 4WD
LOCK, NEUTRAL and 4WD LOW.
The Electronically Shifted transfer case is designed to be
driven in the 2 wheel drive position (2WD) or 4-wheel
drive position (4WD AUTO) for normal street and high-
way conditions (dry hard surfaced roads). Driving the
vehicle in 2WD will have greater fuel economy benefits,
as the front axle is not engaged in 2WD.
For variable driving conditions the 4WD AUTO mode
can be used. In this mode the front axle is engaged, but
the vehicle's power is sent to the rear wheels. 4-wheel
drive will be automatically engaged when the vehicle
senses a loss of traction. Because the front axle is en-
gaged, this mode will result in lower fuel economy than
the 2WD mode.When additional traction is required, the transfer case
4WD LOCK and 4WD LOW positions can be used to lock
the front and rear driveshafts together and force the front
and rear wheels to rotate at the same speed. This is
accomplished by rotating the 4WD Control Switch to the
desired position - see Shifting Procedure section for
specific shifting instructions. The 4WD LOCK and 4WD
LOW positions are designed for loose, slippery road
surfaces only. Driving in the 4WD LOCK and 4WD LOW
positions on dry hard surfaced roads may cause in-
creased tire wear and damage to the driveline compo-
nents.
STARTING AND OPERATING 299
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