1998 DODGE RAM 1500 vin

REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN AN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
NOTE: The blower motor is located on the passen-
ger side of the vehicle under the instrument panel.
The blower motor can be removed from the vehicle
without having to remove the HVAC housing.
(1) Disconnect and isolate the battery negative
cable.
(2) Disconnect the wire harness connector from the
blower motor. (Fig. 5).
(3) Remove the three screws that secure the
blower motor to the HVAC housing.
(4) Remove the blower motor from the HVAC hous-
ing by rotating and tilting the blower motor as
needed for clearance.
INSTALLATION
(1) Align and install the blower motor into the
HVAC housing.
(2) Install the three screws that secure the blower
motor to the HVAC housing. Tighten the screws to
2.2 N´m (20 in. lbs.).
(3) Connect the wire harness connector to the
blower motor.
(4) Reconnect the battery negative cable.
DEFROST DOOR
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THISIS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN AN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Remove the HVAC housing from the vehicle
(Refer to 24 - HEATING & AIR CONDITIONING/
DISTRIBUTION/HVAC HOUSING - REMOVAL).
(2) Disassemble the HVAC housing (Refer to 24 -
HEATING & AIR CONDITIONING/DISTRIBUTION/
HVAC HOUSING - DISASSEMBLY).
(3) Remove the defrost door actuator and sleeve
from the lower half of the HVAC housing (Fig. 6).
(4) Gently slide the defrost door toward the out-
side of the housing. Tilt and lift the door out of the
housing.
(5) Inspect the defrost door, seals and the HVAC
housing for damage or binding and repair or replace
components as required.
INSTALLATION
(1) Position the defrost door pivot shaft into the
pivot hole in the lower half of the HVAC housing.
(2) Install the defrost door actuator and sleeve.
(3) Assemble the HVAC housing (Refer to 24 -
HEATING & AIR CONDITIONING/DISTRIBUTION/
HVAC HOUSING - ASSEMBLY)
(4) Install the HVAC housing (Refer to 24 - HEAT-
ING & AIR CONDITIONING/DISTRIBUTION/HVAC
HOUSING - INSTALLATION)
Fig. 5 HVAC Blower Motor - Typical
1 - RESISTOR BLOCK SCREWS (2)
2 - BLOWER MOTOR RESISTOR BLOCK
3 - RESISTOR BLOCK WIRE CONNECTOR
4 - BLOWER MOTOR SCREW
5 - BLOWER MOTOR
6 - BLOWER MOTOR WIRE CONNECTOR
7 - BLOWER MOTOR SCREW
8 - HVAC HOUSING
9 - WIRE HARNESS RETAINER (2)
10 - BLOWER MOTOR SCREW
DRDISTRIBUTION 24 - 31
BLOWER MOTOR (Continued)

A/C SYSTEM
WARNING: THE AIR CONDITIONING SYSTEM CON-
TAINS REFRIGERANT UNDER HIGH PRESSURE.
SEVERE PERSONAL INJURY MAY RESULT FROM
IMPROPER SERVICE PROCEDURES. REPAIRS
SHOULD ONLY BE PERFORMED BY QUALIFIED
SERVICE PERSONNEL.
AVOID BREATHING THE REFRIGERANT AND
REFRIGERANT OIL VAPOR OR MIST. EXPOSURE
MAY IRRITATE THE EYES, NOSE, AND/OR THROAT.
WEAR EYE PROTECTION WHEN SERVICING THE
AIR CONDITIONING REFRIGERANT SYSTEM. SERI-
OUS EYE INJURY CAN RESULT FROM DIRECT
CONTACT WITH THE REFRIGERANT. IF EYE CON-
TACT OCCURS, SEEK MEDICAL ATTENTION IMME-
DIATELY.
DO NOT EXPOSE THE REFRIGERANT TO OPEN
FLAME. POISONOUS GAS IS CREATED WHEN
REFRIGERANT IS BURNED. AN ELECTRONIC LEAK
DETECTOR IS RECOMMENDED.
IF ACCIDENTAL SYSTEM DISCHARGE OCCURS,
VENTILATE THE WORK AREA BEFORE RESUMING
SERVICE. LARGE AMOUNTS OF REFRIGERANT
RELEASED IN A CLOSED WORK AREA WILL DIS-
PLACE THE OXYGEN AND CAUSE SUFFOCATION.
THE EVAPORATION RATE OF R-134a REFRIGER-
ANT AT AVERAGE TEMPERATURE AND ALTITUDE
IS EXTREMELY HIGH. AS A RESULT, ANYTHING
THAT COMES IN CONTACT WITH THE REFRIGER-
ANT WILL FREEZE. ALWAYS PROTECT THE SKIN
OR DELICATE OBJECTS FROM DIRECT CONTACT
WITH THE REFRIGERANT.
THE R-134a SERVICE EQUIPMENT OR THE VEHI-
CLE REFRIGERANT SYSTEM SHOULD NOT BE
PRESSURE TESTED OR LEAK TESTED WITH COM-
PRESSED AIR. SOME MIXTURES OF AIR AND
R-134a HAVE BEEN SHOWN TO BE COMBUSTIBLE
AT ELEVATED PRESSURES. THESE MIXTURES ARE
POTENTIALLY DANGEROUS, AND MAY RESULT IN
FIRE OR EXPLOSION CAUSING INJURY OR PROP-
ERTY DAMAGE.
CAUTION
A/C SYSTEM
CAUTION: Liquid refrigerant is corrosive to metal
surfaces. Follow the operating instructions supplied
with the service equipment being used.
Never add R-12 to a refrigerant system designed to
use R-134a and do not use R-12 equipment or parts
on the R-134a system. Damage to the system will
result.
R-12 refrigerant oil must not be mixed with R-134arefrigerant oil. They are not compatible and damage
to the system will result.
Do not overcharge the refrigerant system. Over-
charging will cause excessive compressor head
pressure and can cause noise and system failure.
Recover the refrigerant before opening any fitting
or connection. Open the fittings with caution, even
after the system has been discharged. Never open
or loosen a connection before recovering the refrig-
erant.
If equipped, do not remove the secondary retention
clip from any spring-lock coupler connection while
the refrigerant system is under pressure. Recover
the refrigerant before removing the secondary
retention clip. Open the fittings with caution, even
after the system has been discharged. Never open
or loosen a connection before recovering the refrig-
erant.
Do not open the refrigerant system or uncap a
replacement component until you are ready to ser-
vice the system. This will prevent contamination in
the system. Before disconnecting a component,
clean the outside of the fittings thoroughly to pre-
vent contamination from entering the refrigerant
system. Immediately after disconnecting a compo-
nent from the refrigerant system, seal the open fit-
tings with a cap or plug.
Refrigerant oil will absorb moisture from the atmo-
sphere if left uncapped. Do not open a container of
refrigerant oil until you are ready to use it. Replace
the cap on the oil container immediately after using.
Store refrigerant oil only in a clean, airtight, and
moisture-free container.
Keep service tools and the work area clean. Con-
tamination of the refrigerant system must be
avoided.
CAUTION: The use of A/C system sealers may
result in damage to A/C refrigerant recovery/evacu-
ation/recharging equipment and/or A/C systems.
Many federal, state/provincial and local regulations
prohibit the recharge of A/C systems with known
leaks. DaimlerChrysler recommends the detection
of A/C system leaks through the use of approved
leak detectors and fluorescent leak detection dyes.
Vehicles found with A/C system sealers should be
treated as contaminated and replacement of the
entire A/C refrigerant system is recommended. A/C
systems found to be contaminated with A/C system
sealers, A/C stop-leak products or seal conditioners
voids the warranty for the A/C system.
DRPLUMBING 24 - 43
PLUMBING (Continued)

HEATER INLET HOSE
REMOVAL
The heater inlet hose is constructed from rubber
hoses and plastic hose connectors. The ends are
secured to the heater core, engine and engine coolant
reservoir (depending on engine application) by spring
tension clamps.
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING -
WARNING) and (Refer to 24 - HEATING & AIR CON-
DITIONING/PLUMBING - CAUTION).
(1) Drain the engine cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE - COOLING
SYSTEM DRAIN).
(2) Remove the heater hose retaining brackets as
required (depending on engine application).
(3) Using spring tension clamp pliers, compress
and slide the clamps off of each end of the hose being
removed (Fig. 24).
CAUTION: DO NOT apply excessive pressure on
heater tubes or connections when removing heater
hoses. Excessive pressure may damage or deform
the tubes/heater core, causing an engine coolant
leak.
(4) Disconnect each hose end by carefully twisting
the hose back and forth on the tube, while gently
pulling it away from the end of the tube.
(5) If necessary, carefully cut the hose end and
peel the hose off of the tube.
NOTE: Replacement of the heater inlet hose will be
required if the hose ends are cut for removal.
(6) Remove the heater inlet hose from the engine
compartment.
(7) Separate the heater hoses from each other as
required (depending on engine application).
INSTALLATION
(1) If separated, reconnect the heater hoses to each
other as required (depending on engine application).
(2) Position the heater inlet hose into the engine
compartment.
(3) Using spring tension clamp pliers, compress
and slide each clamp away from the end of the hose
being installed.
(4) Install each hose by carefully twisting the hose
back and forth while gently pushing it onto the tube
end.(5) Using spring tension clamp pliers, compress
and slide the clamps onto each end of the hose being
installed.
(6) Install the heater hose retaining brackets as
required (depending on engine application).
(7) Refill the engine cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE - COOLING
SYSTEM REFILL).
HEATER RETURN HOSE
REMOVAL
The heater return hose is constructed from rubber
hoses and plastic hose connectors. The ends are
secured to the heater core, engine and engine coolant
reservoir (depending on engine application) by spring
tension clamps.
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING -
WARNING) and (Refer to 24 - HEATING & AIR CON-
DITIONING/PLUMBING - CAUTION).
Fig. 24 Heater Hoses - Typical
1 - HEATER CORE TUBES
2 - HEATER INLET HOSE
3 - RETAINING BRACKET
4 - HOSE CONNECTOR
5 - SPRING CLAMP
6 - HEATER RETURN HOSE
24 - 64 PLUMBINGDR

(1) Drain the engine cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE - COOLING
SYSTEM DRAIN).
(2) Remove the heater hose retaining brackets as
required (depending on engine application).
(3) Using spring tension clamp pliers, compress
and slide the clamps off of each end of the hose being
removed (Fig. 25).
CAUTION: DO NOT apply excessive pressure on
heater tubes or connections when removing heater
hoses. Excessive pressure may damage or deform
the tubes/heater core, causing an engine coolant
leak.
(4) Disconnect each hose end by carefully twisting
the hose back and forth on the tube, while gently
pulling it away from the end of the tube.
(5) If necessary, carefully cut the hose end and
peel the hose off of the tube.
NOTE: Replacement of the heater return hose will
be required if the hose ends are cut for removal.
(6) Remove the heater return hose from the engine
compartment.
(7) Separate the heater hoses from each other as
required (depending on engine application).INSTALLATION
(1) If separated, reconnect the heater hoses to each
other as required (depending on engine application).
(2) Position the heater return hose into the engine
compartment.
(3) Using spring tension clamp pliers, compress
and slide each clamp away from the end of the hose
being installed.
(4) Install each hose by carefully twisting the hose
back and forth while gently pushing it onto the tube
end.
(5) Using spring tension clamp pliers, compress
and slide the clamps onto each end of the hose being
installed.
(6) Install the heater hose retaining brackets as
required (depending on engine application).
(7) Refill the engine cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE).
LIQUID LINE
DESCRIPTION
The liquid line is the refrigerant line that carries
refrigerant from the A/C condenser to the evaporator.
The liquid line for this model consist of two separate
lines that connect to each other. The liquid lines are
made from light-weight aluminum or steel, and use
braze-less fittings.
The front half of the liquid line contains the fixed
orifice tube. The liquid lines are only serviced as an
assembly, except for the rubber O-ring seals used on
the end fittings. The liquid lines cannot be adjusted
or repaired and, if found to be leaking or damaged,
they must be replaced.
REMOVAL
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING -
WARNING) and (Refer to 24 - HEATING & AIR CON-
DITIONING/PLUMBING - CAUTION).
(1) Disconnect and isolate the battery negative
cable.
(2) If equipped with the diesel engine, remove the
passenger side battery (Refer to 8 - ELECTRICAL/
BATTERY SYSTEM/BATTERY - REMOVAL).
(3) If equipped with the diesel engine, remove the
passenger side battery tray (Refer to 8 - ELECTRI-
CAL/BATTERY SYSTEM/TRAY - REMOVAL).
(4) Recover the refrigerant from the refrigerant
system (Refer to 24 - HEATING & AIR CONDITION-
Fig. 25 Heater Hoses - Typical
1 - HEATER CORE TUBES
2 - HEATER INLET HOSE
3 - RETAINING BRACKET
4 - HOSE CONNECTOR
5 - SPRING CLAMP
6 - HEATER RETURN HOSE
DRPLUMBING 24 - 65
HEATER RETURN HOSE (Continued)

Check the vapor/vacuum lines at the LDP, LDP
filter and EVAP canister purge solenoid for
damage or leaks. If a leak is present, a Diagnos-
tic Trouble Code (DTC) may be set.
(4) Connect electrical connector to LDP.
ORVR
DESCRIPTION
The ORVR (On-Board Refueling Vapor Recovery)
system consists of a unique fuel tank, flow manage-
ment valve, fluid control valve, one-way check valve
and vapor canister.
OPERATION
The ORVR (On-Board Refueling Vapor Recovery)
system is used to remove excess fuel tank vapors.
This is done while the vehicle is being refueled.
Fuel flowing into the fuel filler tube (approx. 1º
I.D.) creates an aspiration effect drawing air into the
fuel fill tube. During refueling, the fuel tank is
vented to the EVAP canister to capture escaping
vapors. With air flowing into the filler tube, there are
no fuel vapors escaping to the atmosphere. Once the
refueling vapors are captured by the EVAP canister,
the vehicle's computer controlled purge system draws
vapor out of the canister for the engine to burn. The
vapor flow is metered by the purge solenoid so that
there is no, or minimal impact on driveability or
tailpipe emissions.
As fuel starts to flow through the fuel fill tube, it
opens the normally closed check valve and enters the
fuel tank. Vapor or air is expelled from the tank
through the control valve and on to the vapor canis-
ter. Vapor is absorbed in the EVAP canister until
vapor flow in the lines stops. This stoppage occurs
following fuel shut-off, or by having the fuel level in
the tank rise high enough to close the control valve.
This control valve contains a float that rises to seal
the large diameter vent path to the EVAP canister.
At this point in the refueling process, fuel tank pres-
sure increases, the check valve closes (preventing liq-
uid fuel from spiting back at the operator), and fuel
then rises up the fuel filler tube to shut off the dis-
pensing nozzle.
PCV VALVE
DESCRIPTION
3.7L V-6 / 4.7L V-8
The 3.7L V-6 and 4.7L V-8 engines are equipped
with a closed crankcase ventilation system and a
Positive Crankcase Ventilation (PCV) valve.
This system consists of:
²a PCV valve mounted to the oil filler housing
(Fig. 10). The PCV valve is sealed to the oil filler
housing with an o-ring.
²the air cleaner housing
²two interconnected breathers threaded into the
rear of each cylinder head (Fig. 11).
²tubes and hoses to connect the system compo-
nents.
Fig. 10 PCV VALVE - 3.7L V-6 / 4.7L V-8
1 - O-RING
2 - LOCATING TABS
3 - CAM LOCK
4 - OIL FILLER TUBE
5 - PCV LINE/HOSE
6 - P C V VA LV E
DREVAPORATIVE EMISSIONS 25 - 17
LEAK DETECTION PUMP (Continued)

DIAGNOSIS AND TESTING - PCV VALVE - 3.7L
V-6/ 4.7L V-8
(1) Disconnect PCV line/hose (Fig. 19) by discon-
necting rubber connecting hose at PCV valve fitting.
(2) Remove PCV valve at oil filler tube by rotating
PCV valve downward until locating tabs have been
freed at cam lock (Fig. 19). After tabs have cleared,
pull valve straight out from filler tube.To prevent
damage to PCV valve locating tabs, valve must
be pointed downward for removal. Do not force
valve from oil filler tube.
(3) After valve is removed, check condition of valve
o-ring (Fig. 19). Also, PCV valve should rattle when
shaken.
(4) Reconnect PCV valve to its connecting line/
hose.
(5) Start engine and bring to idle speed.
(6) If valve is not plugged, a hissing noise will be
heard as air passes through valve. Also, a strong vac-
uum should be felt with a finger placed at valve
inlet.
(7) If vacuum is not felt at valve inlet, check line/
hose for kinks or for obstruction. If necessary, clean
out intake manifold fitting at rear of manifold. Do
this by turning a 1/4 inch drill (by hand) through the
fitting to dislodge any solid particles. Blow out the
fitting with shop air. If necessary, use a smaller drill
to avoid removing any metal from the fitting.
(8)Do not attempt to clean the old PCV valve.
(9) Return PCV valve back to oil filler tube by
placing valve locating tabs (Fig. 19) into cam lock.
Press PCV valve in and rotate valve upward. A slight
click will be felt when tabs have engaged cam lock.
Valve should be pointed towards rear of vehicle.
(10) Connect PCV line/hose and connecting rubber
hose to PCV valve.
(11) Disconnect rubber hose from fresh air fitting
at air cleaner resonator box. Start engine and bring
to idle speed. Hold a piece of stiff paper (such as a
parts tag) loosely over the opening of the discon-
nected rubber hose.
(12) The paper should be drawn against the hose
opening with noticeable force. This will be after
allowing approximately one minute for crankcase
pressure to reduce.
(13) If vacuum is not present, disconnect each PCV
system hose at top of each crankcase breather (Fig.
20). Check for obstructions or restrictions.
(14) If vacuum is still not present, remove each
PCV system crankcase breather (Fig. 20) from each
cylinder head. Check for obstructions or restrictions.
If plugged, replace breather. Tighten breather to 12
N´m (106 in. lbs.) torque. Do not attempt to clean
breather.(15) If vacuum is still not present, disconnect each
PCV system hose at each fitting, and at each check
valve (Fig. 21). Check for obstructions or restrictions.
Fig. 19 PCV VALVE - 3.7L V-6 / 4.7L V-8
1 - O-RING
2 - LOCATING TABS
3 - CAM LOCK
4 - OIL FILLER TUBE
5 - PCV LINE/HOSE
6 - P C V VA LV E
Fig. 20 CRANKCASE BREATHERS (2) - 3.7L V-6 /
4.7L V-8
1 - CRANKCASE BREATHERS (2)
2 - REAR OF ENGINE
25 - 20 EVAPORATIVE EMISSIONSDR
PCV VALVE (Continued)