1998 DODGE RAM 1500 air condition

FRONT AND REAR CASES
Inspect the cases for wear and damage.
Check case condition. If leaks were a problem, look
for gouges and severe scoring of case sealing sur-
faces. Also make sure the front case mounting studs
are in good condition.
Check the front case mounting studs and vent
tube. The tube can be secured with LoctiteŸ 271 or
680 if loose. The stud threads can be cleaned up with
a die if necessary. Also check condition of the fill/
drain plug threads in the rear case. The threads can
be repaired with a thread chaser or tap if necessary.
Or the threads can be repaired with Helicoiltstain-
less steel inserts if required.
OIL PUMP/OIL PICKUP
Examine the oil pump pickup parts. Replace the
pump if any part appears to be worn or damaged. Do
not disassemble the pump as individual parts are not
available. The pump is only available as a complete
assembly. The pickup screen, hose, and tube are the
only serviceable parts and are available separately.
ASSEMBLY
BEARINGS AND SEALS
(1) Remove the input shaft bearing (Fig. 42) from
the front case with suitable snap-ring pliers.
(2) Transfer the retaining ring to the new bearing
if necessary and install the bearing into the front
case.
(3) Remove the front output shaft bearing retain-
ing ring from inside the front case half.
(4) Using Installer 6436 and Handle C-4171,
remove front output shaft bearing.(5) Start front output shaft bearing in case. Then
seat bearing with Handle C-4171 and Installer 6953
(Fig. 43).
(6) Install front output shaft bearing retaining
ring.
(7) Remove the front output shaft rear bearing
with the screw and jaws from Remover L-4454 and
Cup 8148 (Fig. 44).
Fig. 42 Remove Input Gear Bearing
1 - INPUT GEAR BEARING
2 - FRONT CASE
Fig. 43 Install Front Output Shaft Bearing
1 - FRONT CASE
2 - INSTALLER 6953
3 - HANDLE C-4171
Fig. 44 Front Output Shaft Rear Bearing Removal
1 - REAR CASE
2 - SPECIAL TOOL L-4454-1 AND L-4454-3
3 - SPECIAL TOOL 8148
DRTRANSFER CASE - NV244 GENII 21 - 525
TRANSFER CASE - NV244 GENII (Continued)

IDENTIFICATION
A circular ID tag is attached to the rear case of
each transfer case (Fig. 1). The ID tag provides the
transfer case model number, assembly number, serial
number, and low range ratio.
The transfer case serial number also represents
the date of build.
OPERATION
The input gear is splined to the transmission out-
put shaft. The input gear drives the mainshaft
through the planetary assembly and range sleeve.
The front output shaft is operated by a drive chain
that connects the shaft to a drive sprocket on the
mainshaft. The drive sprocket is engaged/disengaged
by the mode fork, which operates the mode sleeve
and hub. The sleeve and hub are not equipped with a
synchronizer mechanism for shifting.
DIAGNOSIS AND TESTING - TRANSFER CASE - NV273
DIAGNOSIS CHART
Condition Possible Cause Correction
Transfer case difficult to shift or will
not shift into desired range.1) Transfer case electronically
controlled shift system malfunction.1) Verify proper operation per the
appropriate diagnostic manual.
2) If vehicle was operated for an
extended period in 4HI mode on
dry surface, driveline torque load
may cause difficulty.2) Drive the vehicle in a straight line
and momentarily release the
accelerator. The transfer case can
then be shifted to the desired mode.
3) Insufficient or incorrect lubricant. 3) Drain and refill transfer case with
the correct quantity of MoparTAT F
+4, Automatic Transmission Fluid.
4) Internal transfer case
components binding, worn, or
damaged.4) Repair or replace components as
necessary.
Transfer case noisy in all drive
modes.1) Insufficient or incorrect lubricant. 1) Drain and refill transfer case with
the correct quantity of MoparTAT F
+4, type 9602, Automatic
Transmission Fluid.
2) Internal transfer case
components binding, worn, or
damaged.2) Repair or replace components as
necessary.
Fig. 1 Transfer Case - Rear View
1 - TRANSFER CASE
2 - IDENTIFICATION TAG
DRTRANSFER CASE - NV273 21 - 543
TRANSFER CASE - NV273 (Continued)

Condition Possible Cause Correction
Transfer case noisy while in, or
jumps out of, 4LO mode.1) Transfer case not completely
engaged in 4LO position.1) While rolling 2-3 MPH and the
transmission in NEUTRAL, or clutch
depressed on vehicles equipped
with a manual transmission, shift
transfer case to the 2WD or 4HI
position, and then back into the 4LO
position.
2) Range fork damaged, inserts
worn, or fork is binding on the shift
rail.2) Repair or replace components as
necessary.
3) Low range gear worn or
damaged.3) Repair or replace components as
necessary.
Lubricant leaking from transfer case
seals or vent.1) Transfer case overfilled. 1) Drain lubricant to the correct
level.
2) Transfer case vent closed or
restricted.2) Clean or replace vent as
necessary.
3) Transfer case seals damaged or
installed incorrectly.3) Replace suspect seal.
Abnormal tire wear. 1) Extended operation in 4HI mode
on dry surfaces,1) Operate vehicle in 2WD mode on
dry surfaces.
REMOVAL
(1) Shift transfer case into 2WD.
(2) Raise vehicle.
(3) Drain transfer case lubricant.
(4) Mark front and rear propeller shafts for align-
ment reference.
(5) Support transmission with jack stand.
(6) Remove the transfer case skid plate, if
equipped.
(7) Disconnect front and rear propeller shafts at
transfer case.
(8) Disconnect transfer case shift motor and mode
sensor wire connectors.
(9) Disconnect transfer case vent hose.
(10) Support transfer case with transmission jack.
(11) Secure transfer case to jack with chains.
(12) Remove nuts attaching transfer case to trans-
mission (Fig. 2).
(13) Pull transfer case and jack rearward to disen-
gage transfer case.
(14) Remove transfer case from under vehicle.
DISASSEMBLY
Position transfer case in a shallow drain pan.
Remove drain plug and drain any remaining lubri-
cant remaining in case.
Fig. 2 Remove Transfer Case - Typical
1 - TRANSMISSION
2 - TRANSFER CASE
3 - MODE SENSOR CONNECTOR
21 - 544 TRANSFER CASE - NV273DR
TRANSFER CASE - NV273 (Continued)

Check the front case mounting studs and vent
tube. The tube can be secured with LoctiteŸ 271 or
680 if loose. The stud threads can be cleaned up with
a die if necessary. Also check condition of the fill/
drain plug threads in the rear case. The threads can
be repaired with a thread chaser or tap if necessary.
Or the threads can be repaired with Helicoiltstain-
less steel inserts if required.
OIL PUMP/OIL PICKUP
Examine the oil pump pickup parts. Replace the
pump if any part appears to be worn or damaged. Do
not disassemble the pump as individual parts are not
available. The pump is only available as a complete
assembly. The pickup screen, hose, and tube are the
only serviceable parts and are available separately.
ASSEMBLY
BEARINGS AND SEALS
(1) Remove the input shaft bearing snap-ring from
the front case half with suitable snap-ring pliers.
(2) Remove the input shaft bearing from the front
case half with Installer 6953 and Handle C-4171
(Fig. 43).
(3) Install the input shaft bearing into the front
case half with Installer 8151 inverted on Handle
C-4171 (Fig. 44).
(4) Install the input shaft bearing snap-ring into
the front case half with suitable snap-ring pliers.(5) Remove the front output shaft front bearing
snap-ring from the front case half.
(6) Using Installer 6953 and Handle C-4171 (Fig.
45), remove the front output shaft front bearing.
Fig. 45 Remove Front Output Shaft Front Bearing
1 - FRONT CASE HALF
2 - HANDLE C-4171
3 - INSTALLER 6953Fig. 43 Remove Input Gear Bearing
1 - FRONT CASE HALF
2 - HANDLE C-4171
3 - INSTALLER 6953
Fig. 44 Install Input Gear Bearing
1 - FRONT CASE HALF
2 - HANDLE C-4171
3 - INSTALLER 8151 (INVERTED)
21 - 556 TRANSFER CASE - NV273DR
TRANSFER CASE - NV273 (Continued)

BODY
TABLE OF CONTENTS
page page
BODY
WARNING
SAFETY PRECAUTIONS AND WARNINGS . . . 1
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - WATER LEAKS . 1
DIAGNOSIS AND TESTING - WIND NOISE . . . 2
STANDARD PROCEDURE
STANDARD PROCEDURE - BODY
LUBRICATION.........................3
STANDARD PROCEDURE - HEAT STAKING . . 3
STANDARD PROCEDURE - PLASTIC BODY
PANEL REPAIR........................3
STANDARD PROCEDURE - BUZZ, SQUEAK
& RATTLE...........................11
SPECIFICATIONS - TORQUE..............12SPECIAL TOOLS
BODY..............................14
TAILGATE..............................15
DOOR - FRONT.........................18
DOORS - REAR.........................28
EXTERIOR.............................36
HOOD.................................46
INSTRUMENT PANEL.....................49
INTERIOR..............................62
PAINT.................................73
SEATS................................75
STATIONARY GLASS.....................86
WEATHERSTRIP/SEALS...................91
BODY STRUCTURE......................95
BODY
WARNING
SAFETY PRECAUTIONS AND WARNINGS
WARNING: USE AN OSHA APPROVED BREATHING
FILTER WHEN SPRAYING PAINT OR SOLVENTS IN
A CONFINED AREA. PERSONAL INJURY CAN
RESULT.
²AVOID PROLONGED SKIN CONTACT WITH
PETROLEUM OR ALCOHOL ± BASED CLEANING
SOLVENTS. PERSONAL INJURY CAN RESULT.
²DO NOT STAND UNDER A HOISTED VEHICLE
THAT IS NOT PROPERLY SUPPORTED ON SAFETY
STANDS. PERSONAL INJURY CAN RESULT.
CAUTION: When holes must be drilled or punched
in an inner body panel, verify depth of space to the
outer body panel, electrical wiring, or other compo-
nents. Damage to vehicle can result.
²Do not weld exterior panels unless combustible
material on the interior of vehicle is removed from
the repair area. Fire or hazardous conditions, can
result.
²Always have a fire extinguisher ready for use
when welding.
²Disconnect the negative (-) cable clamp from
the battery when servicing electrical components
that are live when the ignition is OFF. Damage to
electrical system can result.²Do not use abrasive chemicals or compounds
on painted surfaces. Damage to finish can result.
²Do not use harsh alkaline based cleaning sol-
vents on painted or upholstered surfaces. Damage
to finish or color can result.
²Do not hammer or pound on plastic trim panel
when servicing interior trim. Plastic panels can
break.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - WATER LEAKS
Water leaks can be caused by poor sealing,
improper body component alignment, body seam
porosity, missing plugs, or blocked drain holes. Cen-
trifugal and gravitational force can cause water to
drip from a location away from the actual leak point,
making leak detection difficult. All body sealing
points should be water tight in normal wet-driving
conditions. Water flowing downward from the front of
the vehicle should not enter the passenger or luggage
compartment. Moving sealing surfaces will not
always seal water tight under all conditions. At
times, side glass or door seals will allow water to
enter the passenger compartment during high pres-
sure washing or hard driving rain (severe) condi-
tions. Overcompensating on door or glass
adjustments to stop a water leak that occurs under
severe conditions can cause premature seal wear and
excessive closing or latching effort. After completing
a repair, water test vehicle to verify leak has stopped
before returning vehicle to use.
DRBODY 23 - 1

VISUAL INSPECTION BEFORE WATER LEAK TESTS
Verify that floor and body plugs are in place, body
drains are clear, and body components are properly
aligned and sealed. If component alignment or seal-
ing is necessary, refer to the appropriate section of
this group for proper procedures.
WATER LEAK TESTS
WARNING: DO NOT USE ELECTRIC SHOP LIGHTS
OR TOOLS IN WATER TEST AREA. PERSONAL
INJURY CAN RESULT.
When the conditions causing a water leak have
been determined, simulate the conditions as closely
as possible.
²If a leak occurs with the vehicle parked in a
steady light rain, flood the leak area with an open-
ended garden hose.
²If a leak occurs while driving at highway speeds
in a steady rain, test the leak area with a reasonable
velocity stream or fan spray of water. Direct the
spray in a direction comparable to actual conditions.
²If a leak occurs when the vehicle is parked on an
incline, hoist the end or side of the vehicle to simu-
late this condition. This method can be used when
the leak occurs when the vehicle accelerates, stops or
turns. If the leak occurs on acceleration, hoist the
front of the vehicle. If the leak occurs when braking,
hoist the back of the vehicle. If the leak occurs on left
turns, hoist the left side of the vehicle. If the leak
occurs on right turns, hoist the right side of the vehi-
cle. For hoisting recommendations (Refer to LUBRI-
CATION & MAINTENANCE/HOISTING -
STANDARD PROCEDURE).
WATER LEAK DETECTION
To detect a water leak point-of-entry, do a water
test and watch for water tracks or droplets forming
on the inside of the vehicle. If necessary, remove inte-
rior trim covers or panels to gain visual access to the
leak area. If the hose cannot be positioned without
being held, have someone help do the water test.
Some water leaks must be tested for a considerable
length of time to become apparent. When a leak
appears, find the highest point of the water track or
drop. The highest point usually will show the point of
entry. After leak point has been found, repair the
leak and water test to verify that the leak has
stopped.
Locating the entry point of water that is leaking
into a cavity between panels can be difficult. The
trapped water may splash or run from the cavity,
often at a distance from the entry point. Most water
leaks of this type become apparent after accelerating,
stopping, turning, or when on an incline.MIRROR INSPECTION METHOD
When a leak point area is visually obstructed, use
a suitable mirror to gain visual access. A mirror can
also be used to deflect light to a limited-access area
to assist in locating a leak point.
BRIGHT LIGHT LEAK TEST METHOD
Some water leaks in the luggage compartment can
be detected without water testing. Position the vehi-
cle in a brightly lit area. From inside the darkened
luggage compartment inspect around seals and body
seams. If necessary, have a helper direct a drop light
over the suspected leak areas around the luggage
compartment. If light is visible through a normally
sealed location, water could enter through the open-
ing.
PRESSURIZED LEAK TEST METHOD
When a water leak into the passenger compart-
ment cannot be detected by water testing, pressurize
the passenger compartment and soap test exterior of
the vehicle. To pressurize the passenger compart-
ment, close all doors and windows, start engine, and
set heater control to high blower in HEAT position. If
engine can not be started, connect a charger to the
battery to ensure adequate voltage to the blower.
With interior pressurized, apply dish detergent solu-
tion to suspected leak area on the exterior of the
vehicle. Apply detergent solution with spray device or
soft bristle brush. If soap bubbles occur at a body
seam, joint, seal or gasket, the leak entry point could
be at that location.
DIAGNOSIS AND TESTING - WIND NOISE
Wind noise is the result of most air leaks. Air leaks
can be caused by poor sealing, improper body compo-
nent alignment, body seam porosity, or missing plugs
in the engine compartment or door hinge pillar areas.
All body sealing points should be airtight in normal
driving conditions. Moving sealing surfaces will not
always seal airtight under all conditions. At times,
side glass or door seals will allow wind noise to be
noticed in the passenger compartment during high
cross winds. Over compensating on door or glass
adjustments to stop wind noise that occurs under
severe conditions can cause premature seal wear and
excessive closing or latching effort. After a repair pro-
cedure has been performed, test vehicle to verify
noise has stopped before returning vehicle to use.
VISUAL INSPECTION BEFORE TESTS
Verify that floor and body plugs are in place and
body components are aligned and sealed. If compo-
nent alignment or sealing is necessary, refer to the
appropriate section of this group for proper proce-
dures.
23 - 2 BODYDR
BODY (Continued)

HEATING & AIR CONDITIONING
TABLE OF CONTENTS
page page
HEATING & AIR CONDITIONING
DESCRIPTION
DESCRIPTION - ENGINE COOLING
SYSTEM REQUIREMENTS...............1
DESCRIPTION - HEATER AND AIR
CONDITIONER........................1
OPERATION - HEATER AND AIR
CONDITIONER........................1
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - A/C
PERFORMANCE.......................3DIAGNOSIS AND TESTING - HEATER
PERFORMANCE TEST..................6
SPECIFICATIONS - A/C SYSTEM............7
CONTROLS.............................9
DISTRIBUTION..........................26
PLUMBING.............................41
HEATING & AIR
CONDITIONING
DESCRIPTION
DESCRIPTION - ENGINE COOLING SYSTEM
REQUIREMENTS
To maintain the performance level of the heating,
ventilation and air conditioning (HVAC) system, the
engine cooling system must be properly maintained.
The use of a bug screen is not recommended. Any
obstructions in front of the radiator or A/C condenser
will reduce the performance of the A/C and engine
cooling systems.
The engine cooling system includes the radiator,
thermostat, radiator hoses and the engine coolant
pump. Refer to Cooling for more information before
opening or attempting any service to the engine cool-
ing system.
DESCRIPTION - HEATER AND AIR
CONDITIONER
A manually controlled single zone type heating-air
conditioning system or a manually controlled dual
zone type heating-air conditioning system is available
on this model.
All vehicles are equipped with a common heater,
ventilation and air conditioning (HVAC) housing (Fig.
1). The system combines air conditioning, heating,
and ventilating capabilities in a single unit housing
mounted within the passenger compartment under
the instrument panel. The HVAC housing includes:
²Blower motor
²Blower motor resistor block²Heater core
²Evaporator coil
²Blend door and actuator
²Defrost door and actuator
²Mode door and actuator
²Recirculation door and actuator
Based upon the system and mode selected, condi-
tioned air can exit the HVAC housing through one or
a combination of the three main housing outlets:
defrost, panel or floor. The defrost outlet is located on
the top of the housing, the panel outlet is located on
the face of the housing and the floor outlet is located
on the bottom of the housing. Once the conditioned
air exits the unit housing, it is further directed
through molded plastic ducts to the various outlets in
the vehicle interior. These outlets and their locations
are as follows:
²Defroster Outlet- A single large defroster out-
let is located in the center of the instrument panel
top cover, near the base of the windshield.
²Side Window Demister Outlets- There are
two side window demister outlets, one is located at
each outboard end of the instrument panel top cover,
near the belt line at the A-pillars.
²Panel Outlets- There are four panel outlets in
the instrument panel, one located near each outboard
end of the instrument panel facing the rear of the
vehicle and two located near the top of the instru-
ment panel center bezel.
²Front Floor Outlets- There are two front floor
outlets, one located above each side of the floor panel
center tunnel near the dash panel.
OPERATION - HEATER AND AIR CONDITIONER
The heating and air conditioning systems pulls
outside (ambient) air through the cowl opening at the
base of the windshield, then into the plenum cham-
DRHEATING & AIR CONDITIONING 24 - 1

ber above the heating, ventilation and air condition-
ing (HVAC) housing. On models equipped with air
conditioning, the air passes through the evaporator
coil. Air flow can be directed either through or
around the heater core. This is done by adjusting the
blend door with the temperature control knob on the
A/C-heater control located the instrument panel. The
air flow can then be directed from the panel, floor
and defrost outlets in various combinations using the
mode control knob located on the A/C-heater control.
Air flow velocity can be adjusted with the blower
speed selector located on the A/C-heater control.
NOTE: It is important to keep the air intake opening
clear of debris. Leaf particles and other debris that
is small enough to pass through the cowl opening
screen can accumulate within the HVAC housing.
The closed, warm, damp and dark environment cre-
ated within the housing is ideal for the growth of
certain molds, mildews and other fungi. Any accu-mulation of decaying plant matter provides an addi-
tional food source for fungal spores, which enter
the housing with the fresh intake-air. Excess debris,
as well as objectionable odors created by decaying
plant matter and growing fungi can be discharged
into the passenger compartment during heater-A/C
operation if the air intake opening is not kept clear
of debris.
The heater and air conditioning systems are blend-
air type systems. In a blend-air system, a blend door
controls the amount of unconditioned air (or cooled
air from the evaporator on models with air condition-
ing) that is allowed to flow through, or around, the
heater core. A temperature control knob determines
the discharge air temperature by actuating an elec-
tric motor, which operates the blend door. This allows
an almost immediate control of the output air tem-
perature of the system.
On all models, the outside air intake can be shut
off by selecting the Recirculation Mode with the
mode control knob. This will operate a electric actu-
ated recirculation air door that closes off the outside
fresh air intake and recirculates the air that is
already inside the vehicle.
The air conditioning compressor can be engaged in
any mode by pressing the snowflake, A/C on/off but-
ton. It can also be engaged by placing the mode con-
trol in the mix to defrost positions. This will remove
heat and humidity from the air before it is directed
through or around the heater core. The mode control
knob on the A/C-heater control is used to also direct
the conditioned air to the selected system outlets.
The mode control switch uses an electric motor to
control the mode doors.
The defroster outlet receives airflow from the
HVAC housing through the molded plastic defroster
duct, which connects to the HVAC housing defroster
outlet. The airflow from the defroster outlets is
directed by fixed vanes in the defroster outlet grilles
and cannot be adjusted. The defroster outlet grilles
are integral to the instrument panel top cover.
The side window demister outlets receive airflow
from the HVAC housing through the molded plastic
defroster duct and two molded plastic demister ducts.
The airflow from the side window demister outlets is
directed by fixed vanes in the demister outlet grilles
and cannot be adjusted. The side window demister
outlet grilles are integral to the instrument panel.
The demisters direct air from the HVAC housing
through the outlets located on the top corners of the
instrument panel. The demisters operate when the
mode control knob is positioned in the floor-defrost
and defrost-only settings. Some air may be noticeable
from the demister outlets when the mode control is
in the bi-level to floor positions.
Fig. 1 HVAC Housing - Dual Zone Shown, Single
Zone Typical
1 - NUT
2 - PASSENGER BLEND DOOR ACTUATOR
3 - NUT
4 - INLET BAFFLE
5 - RECIRCULATION DOOR ACTUATOR
6 - RECIRCULATION DOOR
7 - DRIVER SIDE BLEND DOOR ACTUATOR
8 - HVAC HOUSING
9 - BOLT
10 - DEFROSTER DOOR ACTUATOR
11 - MODE DOOR ACTUATOR
24 - 2 HEATING & AIR CONDITIONINGDR
HEATING & AIR CONDITIONING (Continued)