1999 DODGE RAM engine

1) Locate low pressure cut-out switch located on suction
line, near firewall. Ensure system pressure is correct. See
A/C SYSTEM PERFORMANCE test. Disconnect negative battery cable.
Disconnect low pressure cut-out switch connector.
2) Place a jumper wire across terminals of low pressure cut-
out switch harness connector. Connect negative battery cable. Connect
manifold gauge set. Set A/C-heater controls to A/C. Start and operate
engine at idle speed.
3) Using an ohmmeter, check for continuity between switch
terminals. Continuity should exist when suction pressure reading is
between 13-27 psi (.9-1.9 kg/cm
). Continuity should not exist when
suction pressure reading is 10 psi (.7 kg/cm) or lower. If switch is
okay, repair open or short in Brown wire between low pressure cut-out
switch and PCM. If switch is not okay, replace faulty low pressure
cut-out switch.
REMOVAL & INSTALLATION
* PLEASE READ THIS FIRST *
WARNING: To avoid injury from accidental air bag deployment, read and
carefully follow all SERVICE PRECAUTIONS and DISABLING &
ACTIVATING AIR BAG SYSTEM procedures in AIR BAG SYSTEM SAFETY
article.
A/C-HEATER ASSEMBLY
Removal (Dakota & Durango - Front)
1) Disconnect negative battery cable. Drain cooling system.
Discharge A/C system, using approved refrigerant recovery/recycling
equipment. Disconnect refrigerant lines from evaporator and plug or
cover all openings in A/C system. Remove instrument panel. See
INSTRUMENT PANEL .
2) In engine compartment, disconnect heater hoses. Remove 4
A/C-heater assembly nuts from engine compartment firewall. Inside
vehicle, remove A/C-heater assembly support brace screw, and swing
support brace out of way. Move passenger seat rearward.
3) Carefully pull A/C-heater assembly rearward until studs
and heater core tubes clear firewall. Lower A/C-heater assembly and
rotate assembly until studs are facing downward. Remove A/C-heater
assembly from vehicle. See Fig. 4.
4) Place A/C-heater assembly on work bench with assembly
housing cover facing down. Remove 2 screws securing A/C-heater
assembly housing cover to blower motor housing cover. Unplug vacuum
harness connector from panel/defrost door actuator.
5) Remove floor duct from A/C-heater assembly housing. Remove
2 screws securing A/C-heater assembly housing cover to lower housing
near floor outlet. Turn assembly over. Disengage vacuum harness
retainer and vacuum harness. Remove 13 screws securing housing cover.
6) Remove blend-air door lever. Gently pry panel-defrost door
lever off. Pull up on A/C-heater assembly housing cover far enough to
separate cover sealant and remove cover.
Installation
Ensure blower motor housing cover sealant is in place and in
good condition. To complete installation, reverse removal procedure.

assembly towards right side of vehicle and remove rear A/C-heater
assembly.
5) To install, reverse removal procedure. Ensure all wiring
and hoses are clear and not pinched. Tighten bolts and nuts to
specification. See TORQUE SPECIFICATIONS .
Removal (Ram Pickup - Front)
1) Disconnect negative battery cable. Drain cooling system.
In engine compartment, remove coolant hoses from heater core tubes.
Remove coolant overflow bottle.
2) Discharge A/C system, using approved refrigerant
recovery/recycling equipment. Disconnect refrigerant lines from
evaporator and plug or cover all openings in A/C system. Remove
instrument panel. See INSTRUMENT PANEL. Remove Powertrain Control
Module (PCM) and position aside. DO NOT disconnect 60-pin connector
from PCM.
3) Remove attaching nuts from studs on engine compartment
side of dash panel. Remove defrost duct. Disconnect electrical
connectors. Remove attaching nuts from studs in passenger compartment
side of dash panel. Remove A/C-heater assembly from vehicle. See
Fig. 5 .
4) Place A/C-heater assembly upside-down on work bench.
Remove screw securing floor duct to bottom of A/C-heater assembly and
slide floor duct off of center heat duct adapter. Unsnap center heat
duct adapter from bottom of A/C-heater assembly housing. Remove screw
hidden behind adapter. Remove remaining screws and separate A/C-heater
assembly.
Installation
Ensure mode door pivot pins are properly inserted in holes.
To complete installation, reverse removal procedure.
A/C-HEATER CONTROL PANEL R & I
Removal & Installation (Dakota & Durango)
1) Disconnect negative battery cable. On models equipped with
A/T, unlock ignition switch. Set parking brake and place gear selector
lever in "L" position. If equipped, set tilt steering column in lowest
position.
2) On all models, carefully pry bezel away from instrument
panel to disengage clips. Unplug connectors from cigarette lighter and
auxiliary power outlet. Disconnect fog light switch (if equipped).
Remove A/C-heater control panel screws.
3) Pull control panel outward enough to disconnect wiring
connector, vacuum harness, and temperature control cable. Remove A/C-
heater control panel. To install, reverse removal procedure. Adjust
temperature control cable. See TEMPERATURE CONTROL CABLE ADJUSTMENT .
Removal & Installation (Ram Pickup)
1) Disconnect negative battery cable. Reach under driver's
side of instrument panel, near transmission tunnel and unplug A/C-
heater control panel to A/C-heater assembly vacuum harness connector.
Disconnect vacuum harness from center air duct.
2) On models equipped with A/T, unlock ignition switch. Set
parking brake and place gear selector lever in "L" position. If
equipped, set tilt steering column in lowest position.
3) On all models, remove screw securing cluster bezel to
instrument panel. See Fig. 6. Carefully pry bezel away from instrument
panel to disengage clips. Unplug connectors from cigarette lighter and
auxiliary power outlet.
4) Remove 4 screws attaching A/C-heater control panel. Pull
control panel outward enough to disconnect wiring connector, vacuum
harness and temperature control cable. Remove A/C-heater control

procedure.
NOTE: On Durango rear A/C-heater assembly, blower motor and fan are
serviced as an assembly.
Removal (Durango - Rear)
1) Disconnect negative battery cable. Remove headliner from
passenger compartment of vehicle. Remove sun visors and sun visor arm
supports.
2) Remove coat hooks, overhead assist handle and dome light.
If equipped, remove overhead console. Remove air outlet bezel from
rear A/C-assembly. Remove rear blower motor switch. Remove upper
liftgate opening trim. Disengage "A", "B", "C", and "D" pillar trim as
necessary to prevent trim panel interference.
3) Move second and third row seats to cargo position. Move
front seats to full recline position. Remove headliner fasteners.
Carefully bow headliner and remove through lift gate opening.
4) Disconnect "B" pillar drain hoses from "Y" fittings.
Remove lower A/C-heater assembly cover. Disconnect blower motor
harness connector. Remove blower motor and fan assembly. To install,
reverse removal procedure.
Removal (Ram Pickup - Front)
1) Disconnect negative battery cable. Disconnect blower motor
cooling tube. Remove blower motor electrical connector from retainer.
Disconnect electrical connector. See Fig. 5.
2) Remove blower motor and fan assembly mounting screws.
Remove blower motor and fan assembly. Place reference marks on blower
motor and fan for reassembly reference. Remove blower motor fan
retainer clip. Pull blower motor fan off blower motor shaft.
Installation
Align reference marks made during removal. Press blower fan
hub onto blower motor shaft. Ensure retainer clip ears are indexed
over flats of blower motor shaft and fan hub. Ensure blower motor seal
is installed on housing. To complete installation, reverse removal
procedure.
BLOWER MOTOR RESISTOR
Removal & Installation (Dakota & Durango - Front)
Blower motor resistor is located in engine compartment, under
upper right corner of dash panel. Disconnect negative battery cable.
Remove cowl plenum cover to access resistor. Remove blower motor
resistor connector. Remove resistor retaining screws. Remove blower
motor resistor. To install, reverse removal procedure.
Removal & Installation (Durango - Rear)
1) Rear blower motor resistor is located in A/C-heater
assembly. Disconnect negative battery cable. Remove headliner from
passenger compartment of vehicle. Remove sun visors and sun visor arm
supports.
2) Remove coat hooks, overhead assist handle and dome light.
If equipped, remove overhead console. Remove air outlet bezel from
rear A/C-assembly. Remove rear blower motor switch. Remove upper
liftgate opening trim. Disengage "A", "B", "C", and "D" pillar trim as
necessary to prevent trim panel interference.
3) Move second and third row seats to cargo position. Move
front seats to full recline position. Remove headliner fasteners.
Carefully bow headliner and remove through lift gate opening.
4) Disconnect "B" pillar drain hoses from "Y" fittings.
Remove lower A/C-heater assembly cover. Disconnect rear blower motor
resistor connector. Remove screw and rear blower motor resistor. To

install, reverse removal procedure.
Removal & Installation (Ram Pickup - Front)
Blower motor resistor is located under glove box, attached to
blower motor housing. See Fig. 5. Disconnect negative battery cable.
Remove blower motor resistor connector. Remove resistor retaining
screws. Remove blower motor resistor. To install, reverse removal
procedure.
BLOWER MOTOR SWITCH (REAR)
Removal & Installation (Durango)
Disconnect negative battery cable. Pry above indentations at
outer perimeter of rear blower motor switch. Pull rear blower motor
switch and disconnect electrical connector. Remove rear blower motor
switch. To install, reverse removal procedure.
COMPRESSOR
Removal & Installation
1) Disconnect negative battery cable. Discharge A/C system,
using approved refrigerant recovery/recycling equipment. Disconnect
refrigerant lines and plug or cover all openings in A/C system.
2) Remove drive belt. Disconnect compressor electrical leads.
Remove compressor mounting nuts and bolts. Remove compressor. Drain
oil from compressor, and record amount of oil drained.
3) To install, reverse removal procedure. Using new
refrigerant oil, add to compressor the same amount of oil drained from
it. Evacuate and charge A/C system.
CONDENSER
NOTE: Before removing condenser, note location of radiator and
condenser air seals. If air seals are not installed properly,
A/C and engine cooling systems will not perform properly.
Removal
1) Disconnect negative battery cable. Discharge A/C system,
using approved refrigerant recovery/recycling equipment. Disconnect
A/C fittings at inlet and outlet of condenser. Plug or cover all
openings in A/C system.
2) On Dakota, remove bolts securing radiator and fan shroud
to inside of upper radiator crossmember. Remove top mounting bolts
securing condenser to upper crossmember. Tilt top of radiator and fan
shroud toward engine.
3) On Ram Pickup (gasoline engine), remove bolts securing
condenser upper mounting brackets to outside of upper radiator
crossmember. Tilt condenser away from engine compartment far enough to
grasp top of condenser with both hands. On Ram Pickup (diesel engine),\
remove bolts securing condenser to charge air cooler. On all models,
lift condenser assembly from vehicle.
Installation
To install, reverse removal procedure. Install new "O" rings
to fittings. Fill cooling system. Evacuate and charge A/C system.
EVAPORATOR CORE & HEATER CORE
Removal & Installation (Dakota & Durango - Front)
Remove instrument panel. See INSTRUMENT PANEL. Remove A/C-
heater assembly. See A/C-HEATER ASSEMBLY. With A/C-heater housing
removed, remove housing cover. Remove evaporator core or heater core

from housing. To install, reverse removal procedure. Install new "O"
rings to A/C fittings. Evacuate and charge A/C system.
Removal & Installation (Durango - Rear Evaporator Core)
1) Disconnect negative battery cable. Discharge A/C system,
using approved refrigerant recovery/recycling equipment. Remove
headliner from passenger compartment of vehicle. Remove sun visors and
sun visor arm supports.
2) Remove coat hooks, overhead assist handle and dome light.
If equipped, remove overhead console. Remove air outlet bezel from
rear A/C-heater assembly. Remove rear blower motor switch. Remove
upper liftgate opening trim. Disengage "A", "B", "C", and "D" pillar
trim as necessary to prevent trim panel interference.
3) Move second and third row seats to cargo position. Move
front seats to full recline position. Remove headliner fasteners.
Carefully bow headliner and remove through lift gate opening.
4) Disconnect "B" pillar drain hoses from "Y" fittings.
Disconnect "B" pillar refrigerant lines and plug or cover all openings
in A/C system. Remove lower A/C-heater assembly cover. Remove screws
securing refrigerant tube and retaining strap to right side of upper
housing cover. Remove evaporator core. To install, reverse removal
procedure. Install new "O" rings to A/C fittings. Evacuate and charge
A/C system.
Removal & Installation (Ram Pickup - Front)
1) Remove and disassemble A/C-heater housing. See
A/C-HEATER ASSEMBLY . Separate halves of A/C-heater housing and remove
top half. Remove evaporator or heater core from housing.
2) To install, reverse removal procedure. Install new "O"
rings to A/C fittings. Evacuate and charge A/C system. Fill cooling
system. On 5.9L diesel engine, engine is equipped with a one-way check
valve. DO NOT run engine while filling cooling system. Fill engine
with engine turned off.
INSTRUMENT PANEL
Removal & Installation (Dakota & Durango)
1) Disconnect negative battery cable. Disable air bag system.
See AIR BAG SYSTEM SAFETY article. Place front wheels in straight-
ahead position. Remove sill trim from both doorways. Remove kick panel
covers from both sides of vehicle. Remove mounting screws for hood
release handle.
2) Remove steering column trim panel and support bracket.
Remove tilt steering column lever (if equipped). Remove upper and
lower shrouds from steering column. Unplug driver's side air bag
module. Loosen multifunction switch wiring harness connector screw and
disconnect from switch. Screw will remain in connector.
3) Disconnect PRNDL cable. Disconnect shift cable from
steering column. Remove steering coupler lock pin. Remove toe plate
retaining screws. Remove steering column mounting bolts and remove
steering column from vehicle.
4) Remove screw from bulkhead wiring harness connector and
disconnect. Disconnect 2 body wiring harness connectors located next
to bulkhead connector. Disconnect 3 wiring harness connectors, from
junction block, located nearest to dash panel. Disconnect brake light
switch connector. Disconnect Rear Wheel Anti-Lock (RWAL) brake module
(if equipped), located near steering column support brackets.
5) Disconnect plastic retainer clip from parking brake
linkage rod, located at back of parking brake release handle. Remove
rod end from parking brake handle. Remove instrument panel center
support bracket. Unplug vacuum harness connector located at left end
of A/C-heater housing. Disconnect Air Bag Control Module (ACM)
connector.

HIGH
Some possible causes of low side system pressure being high-
to-normal and high side system pressure being too high include:
* Condenser air flow restricted.
* Inoperative cooling fan.
* Faulty expansion valve.
* Refrigerant system overcharged.
* Air in refrigerant system.
* Engine overheating.
LOW SIDE PRESSURE IS HIGH & HIGH SIDE PRESSURE IS LOW
Some possible causes of low side system pressure being too
high and high side system pressure being too low include:
* Compressor belt is slipping.
* Fixed orifice tube not installed.
* Faulty compressor.
LOW SIDE PRESSURE IS LOW & HIGH SIDE PRESSURE IS HIGH
Some possible causes of low side system pressure being too
low and high side system pressure being too high include:
* Restricted refrigerant flow through refrigerant lines.
* Restricted refrigerant flow through expansion valve.
* Restricted refrigerant flow through fixed orifice tube.
* Restricted refrigerant flow through receiver-drier.
* Restricted refrigerant flow through condenser.
BLOWER MOTOR DIAGNOSIS
BLOWER MOTOR INOPERATIVE
Some possible causes of an inoperative blower motor include:
* Faulty fuse.
* Faulty blower motor feed circuit wire harness or
connectors.
* Faulty blower motor ground circuit wire harness or
connector.
* Faulty blower motor resistor.
* Faulty blower motor relay.
* Faulty blower motor switch.
* Faulty A/C-heater mode control switch.
* Faulty blower motor.
BLOWER NOT OPERATING IN ALL SPEEDS
Possible causes of the blower not operating in all speeds
include:
* Faulty fuse.
* Faulty blower motor feed circuit wire harness or
connectors.
* Faulty blower motor relay.
* Faulty blower motor resistor.
* Faulty blower motor switch.

BLOWER MOTOR VIBRATION
Possible causes of blower motor vibration include:
* Improper blower motor mounting.
* Improper blower wheel or fan mounting.
* Blower wheel or fan out of balance.
* Blower motor faulty.
BLOWER MOTOR NOISE
Possible causes of blower motor noise include:
* Foreign material in blower motor housing.
* Foreign material in A/C-heater housing.
* Improper blower motor mounting.
* Improper blower wheel or fan mounting.
* Blower motor faulty.
VACUUM CONTROL SYSTEM DIAGNOSIS
VACUUM CONTROL ONE-WAY CHECK VALVE
NOTE: Some models use brake booster check valve for vacuum source.
These models do not use another in-line vacuum check valve.
1) In engine compartment, locate Black vacuum hose that runs
from brake booster check valve or intake manifold, through firewall
near heater hoses or expansion valve. This supply vacuum hose goes to
A/C-heater control panel vacuum switch.
2) Within Black vacuum hose, disconnect and remove check
valve near intake manifold or brake booster. Connect vacuum gauge to
an external vacuum pump. Start vacuum pump. Plug end of hose probe on
vacuum gauge. Adjust bleed valve on vacuum gauge to obtain an exact
vacuum reading of 8 in. Hg.
3) Unplug and plug end of hose probe on vacuum gauge several
times to ensure exact vacuum reading. Connect vacuum gauge hose probe
to control panel side of check valve. Vacuum gauge reading should be 8
in. Hg. Replace check valve if vacuum leak exists.
4) Connect vacuum gauge hose probe to engine side of check
valve. Vacuum should flow through check valve. Replace check valve if
operation is not as described.
VACUUM CONTROLS
1) This test checks for proper function of control panel
vacuum circuits. Perform steps 1) through 4) under VACUUM CONTROL ONE-\
WAY CHECK VALVE.
2) Connect vacuum gauge hose probe to Black vacuum hose end
that leads to A/C-heater control panel switch. Position vacuum gauge
so gauge reading can be observed from inside vehicle.
3) Operate A/C-heater controls (sliding lever or push
buttons) in all mode positions (floor, defrost, panel, etc.). Pause
after each selection to allow vacuum actuators or motors to energize
and stabilize. Record vacuum gauge reading at each selection.
4) After each selection, vacuum reading should be 7.5-8 in.
Hg. Maximum vacuum reading drop is .75 in. Hg. If proper vacuum
reading cannot be obtained, vacuum leak exists in selected circuit.
5) To check for vacuum leak(s), disconnect 7-way A/C-heater
control panel vacuum harness connector. See Fig. 1. If necessary,
remove control panel from instrument panel to access A/C-heater
control panel vacuum harness connector, or remove lower instrument


A/C S YSTE M G EN ER AL S ER VIC IN G
1999 D odge P ic ku p R 1500
1999 GENERAL SERVICING
A/C System General Servicing
All Models
USING R-134a REFRIGERANT
HANDLING/SAFETY PRECAUTIONS
1) Always work in a well-ventilated, clean area. Refrigerant
is colorless and invisible as a gas. Refrigerant is heavier than
oxygen and will displace oxygen in a confined area. Avoid breathing
refrigerant vapors. Exposure may irritate eyes, nose and throat.
2) Always wear eye protection when working around A/C system
and refrigerant. The system's high pressure can cause severe injury to
eyes and skin if a hose were to burst. If necessary, wear rubber
gloves or other protective clothing.
3) Refrigerant evaporates quickly when exposed to atmosphere,
freezing anything it contacts. If liquid refrigerant contacts eyes or
skin (frostbite), DO NOT rub eyes or skin. Immediately flush affected
area with cool water for 15 minutes and consult a doctor or hospital.
4) Never use R-134a in combination with compressed air for
leak testing. Pressurized R-134a in the presence of oxygen (air
concentrations greater than 60 percent by volume) may form a
combustible mixture. DO NOT introduce compressed air into R-134a
containers (full or empty), A/C system components, or service
equipment.
5) DO NOT expose A/C system components to high temperatures
(steam cleaning for example), as excessive heat will cause refrigerant\
system pressure to increase. Never expose refrigerant directly to open
flame. If refrigerant needs to be warmed, place bottom of refrigerant
tank in warm water. Water temperature MUST NOT exceed 125
F (52C).
CAUTION: When R-134a is exposed to an open flame, drawn into engine,
or detected with a Halide (propane) leak tester, a poisonous
gas is formed. Keep work areas well ventilated.
6) Use care when handling refrigerant containers. DO NOT
drop, strike, puncture, or incinerate containers. Use DOT 4BW or DOT
4BA approved refrigerant containers.
7) Never overfill refrigerant containers. The safe filling
level of a refrigerant container MUST NOT exceed 60\% of the
container's gross weight rating. Store refrigerant containers at
temperatures less than 125
F (52C).
8) R-134a refrigerant is sold and stored in 30- or 50-pound
Light Blue containers, while Freon (R-12) is stored in White colored
containers.
9) Refrigerant R-12 and R-134a must never be mixed, as they
and their desiccants and lubricants are not compatible. If the
refrigerants are mixed, system cross-contamination or A/C system
component failure may occur. Always use separate servicing and
refrigerant recovery/recycling equipment.
10) Read and follow equipment manufacturer's instructions for
all service equipment to be used. The Material Safety Data Sheet
(MSDS), provided by refrigerant manufacturer/supplier, contains
valuable information regarding the safe handling of refrigerants.
IDENTIFYING R-134a SYSTEMS & COMPONENTS