1998 DODGE RAM 1500 IPM

NOTE: The air gap is determined by the spacer
shims. When installing an original, or a new clutch
assembly, try the original shims first. When install-
ing a new clutch onto a compressor that previously
did not have a clutch, use a 1.0, 0.50, and 0.13 mil-
limeter (0.040, 0.020, and 0.005 inch) shims from the
new clutch hardware package that is provided with
the new clutch.
(9) To complete the procedure (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING/A/C COM-
PRESSOR - INSTALLATION).
A/C COMPRESSOR CLUTCH
RELAY
DESCRIPTION
The A/C compressor clutch relay (Fig. 10) is a
International Standards Organization (ISO) micro-re-
lay. Relays conforming to the ISO specifications have
common physical dimensions, current capacities, ter-
minal patterns, and terminal functions. The ISO
micro-relay terminal functions are the same as a con-
ventional ISO relay. However, the ISO micro-relay
terminal pattern (or footprint) is different, the cur-
rent capacity is lower, and the physical dimensions
are smaller than those of the conventional ISO relay.
The A/C compressor clutch relay is located in the
intergrated power module (IPM) in the engine com-
partment. See the fuse and relay layout label affixed
to the inside surface of the IPM cover for A/C com-
pressor clutch relay identification and location.
The black, molded plastic case is the most visible
component of the A/C compressor clutch relay. Fivemale spade-type terminals extend from the bottom of
the base to connect the relay to the vehicle electrical
system, and the ISO designation for each terminal is
molded into the base adjacent to each terminal. The
ISO terminal designations are as follows:
²30 (Common Feed)- This terminal is con-
nected to the movable contact point of the relay.
²85 (Coil Ground)- This terminal is connected
to the ground feed side of the relay control coil.
²86 (Coil Battery)- This terminal is connected
to the battery feed side of the relay control coil.
²87 (Normally Open)- This terminal is con-
nected to the normally open fixed contact point of the
relay.
²87A (Normally Closed)- This terminal is con-
nected to the normally closed fixed contact point of
the relay.
OPERATION
The A/C compressor clutch relay is an electrome-
chanical switch that uses a low current input from
the powertrain control module (PCM) or engine con-
trol module (ECM) depending on engine application,
to control the high current output to the compressor
clutch electromagnetic coil. The movable common
feed contact point is held against the fixed normally
closed contact point by spring pressure. When the
relay coil is energized, an electromagnetic field is
produced by the coil windings. This electromagnetic
field draws the movable relay contact point away
from the fixed normally closed contact point, and
holds it against the fixed normally open contact
point. When the relay coil is de-energized, spring
pressure returns the movable contact point back
against the fixed normally closed contact point. The
resistor or diode is connected in parallel with the
relay coil in the relay, and helps to dissipate voltage
Fig. 9 Check Clutch Air Gap - Typical
1 - FEELER GAUGE
Fig. 10 A/C Compressor Clutch Micro-Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
DRCONTROLS 24 - 13
A/C COMPRESSOR CLUTCH/COIL (Continued)

spikes and electromagnetic interference that can be
generated as the electromagnetic field of the relay
coil collapses.
The A/C compressor clutch relay terminals are con-
nected to the vehicle electrical system through a
receptacle in the integrated power module (IPM). The
inputs and outputs of the A/C compressor clutch
relay include:
²The common feed terminal (30) receives a bat-
tery current input from a fuse in the IPM through a
fused B(+) circuit at all times.
²The coil ground terminal (86) receives a ground
input from the PCM/ECM through the A/C compres-
sor clutch relay control circuit only when the PCM/
ECM electronically pulls the control circuit to
ground.
²The coil battery terminal (85) receives a battery
current input from PTC 1 in the IPM through a
fused ignition switch output (run) circuit only when
the ignition switch is in the On position.
²The normally open terminal (87) provides a bat-
tery current output to the compressor clutch coil
through the A/C compressor clutch relay output cir-
cuit only when the A/C compressor clutch relay coil is
energized.
²The normally closed terminal (87A) is not con-
nected to any circuit in this application, but provides
a battery current output only when the A/C compres-
sor clutch relay coil is de-energized.
Refer to the appropriate wiring information for
diagnosis and testing of the micro-relay and for com-
plete HVAC wiring diagrams.
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the cover from the integrated power
module (IPM) (Fig. 11).
(3) Refer to the fuse and relay layout label on the
IPM cover for compressor clutch relay identification
and location.
(4) Remove the A/C compressor clutch relay from
the IPM.
INSTALLATION
(1) See the fuse and relay layout label affixed to
the underside of the IPM cover for A/C compressor
clutch relay location.
(2) Position the A/C compressor clutch relay in the
proper receptacle in the IPM.
(3) Align the A/C compressor clutch relay termi-
nals with the terminal cavities in the IPM receptacle.
(4) Push down firmly on the A/C compressor clutch
relay until the terminals are fully seated in the ter-
minal cavities in the IPM receptacle.
(5) Install the cover onto the IPM.(6) Reconnect the negative battery cable.
A/C HEATER CONTROL
DESCRIPTION
The heater and air conditioning systems use elec-
trical controls. These controls provide the vehicle
operator with a number of setting options to help
control the climate and comfort within the vehicle.
The A/C-heater control for the Single Zone system
(Fig. 12) or Dual Zone system (Fig. 13) is located to
the right of the instrument cluster on the instrument
panel.
The Single Zone control panel contains a rotary-
type temperature control switch, a rotary-type mode
control switch and a rotary-type blower motor speed
switch. The A/C-heater control also has a push but-
ton to activate the optional heated side view mirror
defroster elements and to turn the A/C on.
The Dual Zone control panel contains a pair of slid-
er-type temperature control switches, a rotary-type
mode control switch and a rotary-type blower motor
speed switch. The control also has buttons to activate
the optional heated sideview mirror defroster ele-
ments, turn the A/C on and set the system to Max
A/C.
The A/C-heater control panel cannot be repaired. If
faulty or damaged, the entire unit must be replaced.
Fig. 11 Integrated Power Module (IPM)
1 - BATTERY
2 - INTEGRATED POWER MODULE (IPM)
24 - 14 CONTROLSDR
A/C COMPRESSOR CLUTCH RELAY (Continued)

PLUMBING
TABLE OF CONTENTS
page page
PLUMBING
DESCRIPTION - REFRIGERANT LINE.......42
OPERATION- REFRIGERANT LINES........42
WARNING
ENGINE COOLING SYSTEM.............42
A/C SYSTEM.........................43
CAUTION
A/C SYSTEM.........................43
DIAGNOSIS AND TESTING - REFRIGERANT
SYSTEM LEAKS......................44
STANDARD PROCEDURE
STANDARD PROCEDURE - HANDLING
TUBING AND FITTINGS.................45
STANDARD PROCEDURE - DIODE
REPLACEMENT.......................45
STANDARD PROCEDURE - REFRIGERANT
SYSTEM SERVICE EQUIPMENT..........46
STANDARD PROCEDURE - REFRIGERANT
RECOVERY..........................47
STANDARD PROCEDURE - REFRIGERANT
SYSTEM EVACUATE...................47
STANDARD PROCEDURE - REFRIGERANT
SYSTEM CHARGE.....................47
A/C COMPRESSOR
DESCRIPTION
DESCRIPTION - A/C COMPRESSOR.......48
DESCRIPTION - HIGH PRESSURE RELIEF
VALVE..............................48
OPERATION
OPERATION - A/C COMPRESSOR........48
OPERATION - HIGH PRESSURE RELIEF
VALVE..............................48
DIAGNOSIS AND TESTING - A/C
COMPRESSOR.......................49
REMOVAL.............................49
INSTALLATION.........................51
A/C CONDENSER
DESCRIPTION.........................52
OPERATION...........................52
REMOVAL
REMOVAL - 3.7, 4.7 AND 5.7L ENGINES....52
REMOVAL - 5.9L DIESEL ENGINE.........53
INSTALLATION
INSTALLATION - 3.7, 4.7 AND 5.7L ENGINES . 53
INSTALLATION - 5.9L DIESEL ENGINE.....54
A/C CONDENSER FAN
REMOVAL - 3.7, 4.7 and 5.7L ENGINES......55
INSTALLATION - 3.7, 4.7 and 5.7L ENGINES . . . 55A/C DISCHARGE LINE
DESCRIPTION.........................56
REMOVAL
REMOVAL - 5.9L DIESEL ENGINE.........56
REMOVAL - 3.7L/4.7L AND 5.7L HEMI
ENGINE.............................57
INSTALLATION
INSTALLATION - 5.9L DIESEL ENGINE.....58
INSTALLATION - 3.7L/4.7L AND 5.7L HEMI
ENGINE.............................59
A/C EVAPORATOR
DESCRIPTION.........................59
OPERATION...........................59
REMOVAL.............................60
INSTALLATION.........................60
A/C ORIFICE TUBE
DESCRIPTION.........................60
OPERATION...........................60
DIAGNOSIS AND TESTING - A/C ORIFICE
TUBE...............................61
ACCUMULATOR
DESCRIPTION.........................61
OPERATION...........................61
REMOVAL.............................61
INSTALLATION.........................62
HEATER CORE
DESCRIPTION.........................63
OPERATION...........................63
REMOVAL.............................63
INSTALLATION.........................63
HEATER INLET HOSE
REMOVAL.............................64
INSTALLATION.........................64
HEATER RETURN HOSE
REMOVAL.............................64
INSTALLATION.........................65
LIQUID LINE
DESCRIPTION.........................65
REMOVAL.............................65
INSTALLATION.........................66
REFRIGERANT
DESCRIPTION.........................67
OPERATION...........................67
REFRIGERANT LINE COUPLER
DESCRIPTION.........................67
OPERATION...........................67
REMOVAL.............................68
INSTALLATION.........................68
DRPLUMBING 24 - 41

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)

DIAGNOSIS AND TESTING - REFRIGERANT
SYSTEM LEAKS
WARNING: R-134a SERVICE EQUIPMENT OR VEHI-
CLE A/C SYSTEM SHOULD NOT BE PRESSURE
TESTED OR LEAK TESTED WITH COMPRESSED
AIR. MIXTURE OF AIR and R-134a CAN BE COM-
BUSTIBLE AT ELEVATED PRESSURES. THESE MIX-
TURES ARE POTENTIALLY DANGEROUS AND MAY
RESULT IN FIRE OR EXPLOSION CAUSING INJURY
OR PROPERTY DAMAGE.
AVOID BREATHING A/C REFRIGERANT AND LUBRI-
CANT VAPOR OR MIST. EXPOSURE MAY IRRITATE
EYES, NOSE AND THROAT. USE ONLY APPROVED
SERVICE EQUIPMENT MEETING SAE REQUIRE-
MENTS TO DISCHARGE R-134a SYSTEM. IF ACCI-
DENTAL SYSTEM DISCHARGE OCCURS,
VENTILATE WORK AREA BEFORE RESUMING SER-
VICE.
NOTE: The refrigerant system does come from the
factory with a yellow tracer dye already installed to
aid in detection of leaks.
If the A/C system is not cooling properly, determine
if the refrigerant system is fully charged with
R-134a. This is accomplished by performing a system
Charge Level-Check or Fill. If while performing this
test A/C liquid line pressure is less than 345 kPa (50
psi) proceed to System Empty procedure. If liquid
line pressure is greater than 345 kPa (50 psi) proceed
to System Low procedure. If the refrigerant system is
empty or low in refrigerant charge, a leak at any line
fitting or component seal is likely. A review of the fit-
tings, lines and components for oily residue is an
indication of the leak location. To detect a leak in the
refrigerant system, perform one of the following pro-
cedures as indicated by the symptoms.
SYSTEM EMPTY
(1) Evacuate the refrigerant system to the lowest
degree of vacuum possible (approx. 28 in Hg.). Deter-
mine if the system holds a vacuum for 15 minutes. If
vacuum is held, a leak is probably not present. If sys-
tem will not maintain vacuum level, proceed with
this procedure.(2) Prepare a 0.284 Kg. (10 oz.) refrigerant charge
to be injected into the system.
(3) Connect and dispense 0.284 Kg. (10 oz.) of
refrigerant into the evacuated refrigerant system.
(4) Proceed to Step 2 of System Low procedure.
SYSTEM LOW
(1) Determine if there is any (R-134a) refrigerant
in the system.
(2) Position the vehicle in a wind free work area.
This will aid in detecting small leaks.
(3) Bring the refrigerant system up to operating
temperature and pressure. This is done by allowing
the engine to run for five minutes with the system
set to the following:
²Transmission in Park or Neutral with parking
brake set
²Engine idling at 700 rpm
²A/C controls set in 100 percent outside air
²Blower switch in the high A/C position
²A/C in the ON position
²Open all windows
CAUTION: A leak detector designed for R-12 refrig-
erant (only) will not detect leaks in a R-134a refrig-
erant system.
(4) Shut off the vehicle and wait 2 to 7 minutes.
Then use an Electronic Leak Detector that is
designed to detect R-134a type refrigerant and search
for leaks. Fittings, lines, or components that appear
to be oily usually indicates a refrigerant leak. To
inspect the evaporator core for leaks, insert the leak
detector probe into the drain tube opening or a heat
duct. A R-134a dye is available to aid in leak detec-
tion, use only DaimlerChrysler approved refrigerant
dye.
24 - 44 PLUMBINGDR
PLUMBING (Continued)

STANDARD PROCEDURE - REFRIGERANT
SYSTEM SERVICE EQUIPMENT
WARNING: EYE PROTECTION MUST BE WORN
WHEN SERVICING AN AIR CONDITIONING REFRIG-
ERANT SYSTEM. TURN OFF (ROTATE CLOCKWISE)
ALL VALVES ON THE EQUIPMENT BEING USED
BEFORE CONNECTING TO, OR DISCONNECTING
FROM THE REFRIGERANT SYSTEM. FAILURE TO
OBSERVE THESE WARNINGS MAY RESULT IN PER-
SONAL INJURY.
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).
When servicing the air conditioning system, a
R-134a refrigerant recovery/recycling/charging sta-
tion that meets SAE Standard J2210 must be used
(Fig. 2). Contact an automotive service equipment
supplier for refrigerant recovery/recycling/charging
equipment. Refer to the operating instructions sup-
plied by the equipment manufacturer for proper care
and use of this equipment.
A manifold gauge set may be needed with some
recovery/recycling/charging equipment (Fig. 3). The
service hoses on the gauge set being used should
have manual (turn wheel), or automatic back-flow
valves at the service port connector ends. This will
prevent refrigerant from being released into the
atmosphere.
MANIFOLD GAUGE SET CONNECTIONS
CAUTION: Do not use an R-12 manifold gauge set
on an R-134a system. The refrigerants are not com-
patible and system damage will result.
LOW PRESSURE GAUGE HOSE The low pressure
hose (Blue with Black stripe) attaches to the low side
service port. This service port is located on the suc-
tion line between the accumulator outlet port and the
A/C compressor.
HIGH PRESSURE GAUGE HOSE The high pres-
sure hose (Red with Black stripe) attaches to the
high side service port. This service port is located on
the discharge line near the A/C compressor. On this
model, an A/C pressure transducer is installed onto
the high pressure service port. A/C high side pres-
sures can be read using a DRBIIItscan tool. Refer to
Body Diagnostic Procedures.
RECOVERY/RECYCLING/EVACUATION/CHARG-
ING HOSE The center manifold hose (Yellow, or
White, with Black stripe) is used to recover, evacu-
ate, and charge the refrigerant system. When the low
or high pressure valves on the manifold gauge set
are opened, the refrigerant in the system will escape
through this hose.
Fig. 2 Refrigerant Recovery/Recycling Station -
Typical
1 - R-134a REFRIGERANT STATION
Fig. 3 MANIFOLD GAUGE SET - TYPICAL
1 - HIGH PRESSURE GAUGE
2 - VALVE
3 - VACUUM/REFRIGERANT HOSE (YELLOW W/ BLACK STRIPE)
4 - HIGH PRESSURE HOSE (RED W/ BLACK STRIPE)
5 - LOW PRESSURE HOSE (BLUE W/ BLACK STRIPE)
6 - VALVE
7 - LOW PRESSURE GAUGE
24 - 46 PLUMBINGDR
PLUMBING (Continued)

STANDARD PROCEDURE - REFRIGERANT
RECOVERY
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).
A R-134a refrigerant recovery/recycling/charging
station that meets SAE Standard J2210 must be
used to recover the refrigerant from an R-134a refrig-
erant system. Refer to the operating instructions sup-
plied by the equipment manufacturer for the proper
care and use of this equipment.
STANDARD PROCEDURE - REFRIGERANT
SYSTEM EVACUATE
NOTE: Special effort must be used to prevent mois-
ture from entering the A/C system oil. Moisture in
the oil is very difficult to remove and will cause a
reliability problem with the compressor.
If a compressor designed to use R-134a refrigerant
is left open to the atmosphere for an extended period
of time. It is recommended that the refrigerant oil be
drained and replaced with new oil or a new compres-
sor be used. This will eliminate the possibility of con-
taminating the refrigerant system.
If the refrigerant system has been open to the
atmosphere, it must be evacuated before the system
can be filled. Moisture and air mixed with the refrig-
erant will raise the compressor head pressure above
acceptable operating levels. This will reduce the per-
formance of the air conditioner and damage the com-
pressor. Moisture will boil at near room temperature
when exposed to vacuum. To evacuate the refrigerant
system:
NOTE: When connecting the service equipment
coupling to the line fitting, verify that the valve of
the coupling is fully closed. This will reduce the
amount of effort required to make the connection.
(1) Recover the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE).
(2) Connect a suitable charging station, refrigerant
recovery machine or a manifold gauge set with vac-
uum pump and refrigerant recovery equipment.
(3) Open the suction and discharge valves and
start the vacuum pump. The vacuum pump should
run a minimum of 45 minutes prior to charge to
eliminate all moisture in system. When the suction
gauge reads -88 kPa (- 26 in. Hg) vacuum or greaterfor 30 minutes, close all valves and turn off vacuum
pump. If the system fails to reach specified vacuum,
the refrigerant system likely has a leak that must be
corrected. If the refrigerant system maintains speci-
fied vacuum for at least 30 minutes, start the vac-
uum pump, open the suction and discharge valves.
Then allow the system to evacuate an additional 10
minutes.
(4) Close all valves. Turn off and disconnect the
vacuum pump.
(5) Charge the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE).
STANDARD PROCEDURE - REFRIGERANT
SYSTEM CHARGE
WARNING: REVIEW SAFETY PRECAUTIONS AND
WARNINGS IN THIS GROUP BEFORE CHARGING
THE REFRIGERANT SYSTEM.
AVOID BREATHING A/C REFRIGERANT AND LUBRI-
CANT VAPOR OR MIST. EXPOSURE MAY IRRITATE
EYES, NOSE AND THROAT. USE ONLY APPROVED
SERVICE EQUIPMENT MEETING SAE REQUIRE-
MENTS TO DISCHARGE R-134a SYSTEM. IF ACCI-
DENTAL SYSTEM DISCHARGE OCCURS,
VENTILATE WORK AREA BEFORE RESUMING SER-
VICE.
R-134a SERVICE EQUIPMENT OR VEHICLE A/C
SYSTEM SHOULD NOT BE PRESSURE TESTED OR
LEAK TESTED WITH COMPRESSED AIR. MIXTURE
OF AIR and R-134a CAN BE COMBUSTIBLE AT ELE-
VATED PRESSURES. THESE MIXTURES ARE
POTENTIALLY DANGEROUS AND MAY RESULT IN
FIRE OR EXPLOSION CAUSING INJURY OR PROP-
ERTY DAMAGE.
CAUTION: Do not overcharge refrigerant system, as
excessive compressor head pressure can cause
noise and system failure.
CAUTION: A small amount of refrigerant oil is
removed from the A/C system each time the refrig-
erant system is recovered and evacuated. Before
charging the A/C system, you MUST replenish any
oil lost during the recovery process. Refer the
equipment manufacturer instructions for more infor-
mation.
The procedure below should be used to fill the
refrigerant charge in the air conditioning system.
This A/C system does not have or use a sight glass to
check or charge the system.
DRPLUMBING 24 - 47
PLUMBING (Continued)

After the system has been tested for leaks and
evacuated, a refrigerant (R-134a) charge can be
injected into the system.
NOTE: When connecting the service equipment
coupling to the line fitting, verify that the valve of
the coupling is fully closed. This will reduce the
amount of effort required to make the connection.
(1) If using a separate vacuum pump close all
valves before disconnecting pump. Connect manifold
gauge set to the A/C service ports.
NOTE: Always refer to the underhood HVAC Speci-
fication label for the refrigerant fill level of the vehi-
cle being serviced.
(2) Measure refrigerant (refer to capacities). Refer
to the instructions provided with the equipment
being used.
(3) Verify engine is shut off. Open the suction and
discharge valves. Open the charge valve to allow the
refrigerant to flow into the system. When the trans-
fer of refrigerant has stopped, close the suction and
discharge valve.
(4) If all of the charge did not transfer from the
dispensing device, put vehicle controls into the fol-
lowing mode:
²Automatic transmission in park or manual
transmission in neutral
²Engine at idle
²A/C mode control set to outside air
²A/C mode control set to panel mode
²A/C temperature control set to full cool
²Blower motor control set on highest speed
²Vehicle windows closed
If the A/C compressor does not engage, test the
compressor clutch control circuit and correct any fail-
ure (Refer to 8 - ELECTRICAL/WIRING DIAGRAM
INFORMATION - DIAGNOSIS AND TESTING).
(5) Open the suction valve to allow the remaining
refrigerant to transfer to the system.
WARNING: TAKE CARE NOT TO OPEN THE DIS-
CHARGE (HIGH-PRESSURE) VALVE AT THIS TIME.
(6) Close all valves and test the A/C system perfor-
mance.
(7) Disconnect the charging station or manifold
gauge set. Install the service port caps.
REFRIGERANT CHARGE CAPACITY
The R-134a refrigerant system charge capacity for
this vehicle can be found on the underhood HVAC
specfication tag.
A/C COMPRESSOR
DESCRIPTION
DESCRIPTION - A/C COMPRESSOR
The A/C system on models equipped with the 5.9L
engine use a Sanden SD-7 reciprocating swash plate-
type compressor. This compressor has a fixed dis-
placement of 165 cubic centimeter (10.068 cubic
inches) and has both the suction and discharge ports
located on the cylinder head.
The A/C system on models equipped with the 3.7L,
4.7L and 5.7L engines use a Denso 10S17 reciprocat-
ing swash plate-type compressor. This compressor
has a fixed displacement of 170 cubic centimeter and
has both the suction and discharge ports located on
the cylinder head.
A label identifying the use of R-134a refrigerant is
located on both A/C compressors.
DESCRIPTION - HIGH PRESSURE RELIEF
VALVE
A high pressure relief valve is located on the com-
pressor cylinder head, which is on the rear of the
compressor. This mechanical valve is designed to
vent refrigerant from the system to protect against
damage to the compressor and other system compo-
nents, caused by condenser air flow restriction or an
overcharge of refrigerant.
OPERATION
OPERATION - A/C COMPRESSOR
The A/C compressor is driven by the engine
through an electric clutch, drive pulley and belt
arrangement. The compressor is lubricated by refrig-
erant oil that is circulated throughout the refrigerant
system with the refrigerant.
The compressor draws in low-pressure refrigerant
vapor from the evaporator through its suction port. It
then compresses the refrigerant into a high-pressure,
high-temperature refrigerant vapor, which is then
pumped to the condenser through the compressor dis-
charge port.
The compressor cannot be repaired. If faulty or
damaged, the entire compressor assembly must be
replaced. The compressor clutch, pulley and clutch
coil are available for service.
OPERATION - HIGH PRESSURE RELIEF VALVE
The high pressure relief valve vents the system
when a discharge pressure of 3445 to 4135 kPa (500
to 600 psi) or above is reached. The valve closes
24 - 48 PLUMBINGDR
PLUMBING (Continued)