1995 JEEP CHEROKEE Compressor

SECOND BRAKE ASSEMBLY
(1) Lubricate and install new O-rings on brake pis-
ton. Then install brake piston in drum.
(2) Install return springs and retainer on brake
piston.
(3) Compress return springs with shop press and
Compressor Tool 7538. Install piston snap ring and
remove brake assembly from press.
(4) Check brake piston operation with low pressure
compressed air (Fig. 7). Apply air pressure through
feed hole in drum. Piston should move smoothly
when applying-releasing air pressure.(5) Coat thrust washer with petroleum jelly and
install it in drum. Be sure washer notches are
aligned with tabs on spring retainer (Fig. 8).
(6) Set brake components aside for final assembly.
Fig. 7 Checking Second Brake Piston Operation
Fig. 8 Installing Second Brake Thrust Washer
JAW-4 TRANSMISSION OVERHAUL 21 - 243

U-joint is worn it will cause vibration with almost
any vehicle speed/engine torque condition.
DSYÐDrive Shaft and Yokes:Vehicle speed sen-
sitive, mechanical/audible vibration. The condition
will not cause vibration below 35 mph (56 km/h). Ex-
cessive runout, unbalance or dents and bends in the
shaft will cause the vibration. Identify the actual
cause and repair/replace as necessary.
WBÐWheel Bearings:Vehicle speed sensitive,
mechanical/audible vibration. Loose wheel bearings
cause shimmy-like vibration at 35 mph (56 km/h)
and above. Worn bearings will also produce a growl
noise at low vehicle speed and a whine noise at high
vehicle speed. The wheel bearings must be adjusted
or replaced, as applicable.
ANÐAxle Noise:Engine torque/vehicle speed sen-
sitive, mechanical/audible vibration. The axle will not
cause mechanical vibration unless the axle shaft is
bent. Worn or damaged axle pinion shaft or differen-
tial gears and bearings will cause noise. Replace the
defective component(s) as necessary.
SSCÐSuspension and Steering Components:
Vehicle speed sensitive, mechanical vibration. Worn
suspension/steering components can cause mechani-
cal vibration at speeds above 20 mph (32 km/h).
Identify and repair or replace the defective compo-
nent(s).EAÐEngine Driven Accessories:Engine speed
sensitive, mechanical/audible vibration. Vibration can
be caused by loose or broken A/C compressor, PS
pump, water pump, generator or brackets, etc. Usu-
ally more noticeable when the transmission is shifted
into the NEUTRAL position and the engine speed
(rpm) increased. Inspect the engine driven accesso-
ries in the engine compartment. Repair/replace as
necessary.
ADBÐAccessory Drive Belts:Engine speed sen-
sitive, audible vibration. Worn drive belts can cause a
vibration that produces either a droning, fluttering or
rumbling noise. Inspect the drive belt(s) and tighten/
replace as necessary.
DEMÐDamaged Engine or Transmission Sup-
port Mounts:Engine speed sensitive, mechanical/
audible vibration. If a support mount is worn, noise
or vibration will occur. Inspect the support mounts
and repair/replace as necessary.
ESÐExhaust System:Engine speed sensitive,
mechanical/audible vibration. If loose exhaust compo-
nents contact the vehicle body they will cause noise
and vibration. Inspect the exhaust system for loose,
broken and mis-aligned components and repair/re-
place as necessary.
VIBRATION DIAGNOSIS
JWHEELS AND TIRES 22 - 11

(5) Remove the retaining screws and the air intake
adapters from the grille panel (Fig. 6).
(6) Remove the bolts and washers that attach the
grille panel to the fenders (Fig. 7).
(7) Remove the bolts, washers and spacers that at-
tach the grille panel to the front crossmember (Fig.
8).
(8) Remove the nuts that attach the radiator sup-
port rods to the front brackets (Fig. 9). Remove the
rods from the brackets.
(9) Tilt the grille panel forward and disconnect the
head lamp, turn signal and marker lamp wire har-
ness connectors.
(10) For vehicles equipped with A/C, discharge the
A/C system. Disconnect the high pressure hose at the
sight glass connection and at the compressor. Cap thehose and fittings to prevent foreign material entry. If
necessary, refer to Group 24ÐHeating And Air Con-
ditioning.
(11) Remove the grille panel from the vehicle (Fig.
8).
(12) If a replacement radiator grille panel will be
installed, remove the grille applique (Fig. 8) and
transfer the lamps, the headlamp buckets and the re-
taining brackets.
Fig. 7 Grille Panel Front Bolt
Fig. 8 Radiator Grille Applique and Grille Panel
Fig. 6 Air Intake and Radiator Baffle Adapters
23 - 106 EXTERIOR COMPONENTSÐYJJ

HEATING AND AIR CONDITIONING
CONTENTS
page page
COMPONENT SERVICEÐXJ VEHICLES...... 23
COMPONENT SERVICEÐYJ VEHICLES...... 32
COMPRESSOR SERVICE.................. 19
GENERAL INFORMATION.................. 1
HEATING AND AIR CONDITIONING TEST
PROCEDURES......................... 15REFRIGERANT SERVICE AND PERFORMANCE
TEST................................ 11
TORQUE SPECIFICATIONS................ 37
WARNINGS, CAUTIONS AND SERVICE
PRECAUTIONS......................... 9
GENERAL INFORMATION
INDEX
page page
A/C Components.......................... 4
Heater and A/C Operation.................... 1
Manifold Gauge Set........................ 7Refrigerant............................... 7
Refrigerant Equipment...................... 7
HEATER AND A/C OPERATION
HEATERÐXJ
A blend-air heating system is used in XJ vehicles.
The temperature of heated air is controlled by regu-
lating the quantity of air flow through the heater
core. This is accomplished by blending outside air
with heated air from the heater core to obtain the de-
sired discharge temperature. A temperature control
lever on the heater control determines air flow
through the heater core. The lever uses a cable to op-erate the blend-air door. This door controls air flow
through the core. Vacuum motors are used to actuate
and position the remaining door in the system.
On left hand drive (LHD) XJ vehicles a water valve
controls coolant flow to the heater core. The valve is
vacuum operated. When vacuum is applied, the valve
opens and coolant is directed through the heater core
and back to the engine. When the water valve is
closed (no vacuum applied) coolant flow bypasses the
heater core back to the engine.
JHEATING AND AIR CONDITIONING 24 - 1

motor is controlled by a vacuum switch in the heater
control panel. The vent air doors are opened and
closed by a cable and linkage operated by the air con-
trol lever. Fresh air intake occurs only when the le-
ver is in the VENT position.
AIR CONDITIONING
The compressor increases the pressure and temper-
ature of the refrigerant. The heated refrigerant vapor
is pumped into the condenser where it is cooled by
air passing over the condenser fins. As the refriger-
ant cools in the condenser, it condenses into a liquid.
Still under high pressure, the liquid refrigerant
passes into the receiver. The receiver acts as a reser-
voir to furnish refrigerant to the expansion valve at
all times. From the receiver, the high pressure liquid
refrigerant passes to the expansion valve. The expan-
sion valve meters refrigerant into the evaporator.
The low pressure is maintained by the suction side of
the compressor. As it enters the evaporator, the re-
frigerant begins to absorb heat from the air passing
over the evaporator core. Having given up its heat to
boil the refrigerant, the air is cooled and passes into
the passenger compartment. From the evaporator the
vaporized refrigerant is drawn back to the compres-
sor to repeat the cycle.
A/C COMPONENTS
COMPRESSOR:The SD7H15 Compressor is used
on all models. The purpose of the compressor is to
compress the low-pressure refrigerant vapor into a
high pressure, high temperature vapor. The compres-
sor is serviced as a assembly only.
CLUTCH PULLEY AND COIL:They are
mounted on the compressor and providing a way to
drive the compressor. The compressor clutch and coil
are the only serviced parts on the SD7H15 compres-
sor. When the compressor is not in operation, the
pulley free wheels on the clutch hub bearing. When
the coil is energized the clutch plate is magnetically
engaged with the pulley and turns the compressor
shaft.
CONDENSER:The condenser is located in front of
the engine radiator. Its function is to cool the hot
high pressure refrigerant gas. This causes it to con-
dense into high pressure liquid refrigerant.
EXPANSION VALVE:The expansion valve is lo-
cated in the engine compartment on XJ vehicles. On
YJ vehicles it is located behind the A/C housing. Its
function is to meter refrigerant into the evaporator in
accordance with cooling requirements.
Fig. 3 Fresh Air Intake System Components
24 - 4 HEATING AND AIR CONDITIONINGJ

EVAPORATOR COIL:The coil is located in the
A/C housing. Its function is to remove heat and de-
humidify the air before it enters the vehicle.
FIN SENSING CYCLING CLUTCH SWITCH:
The switch is attached to the evaporator coil with the
temperature sensing probe inserted into the coil fins.
This switch controls evaporator temperature and pre-
vents condensate water on the evaporator coil from
freezing. It does this by sending signals to the Pow-
ertrain Control Module (PCM) to cycling the com-
pressor clutch on and off. This switch is used onXJ
only.
FILTER-DRIER:The drier is used to remove any
traces of moisture from the refrigerant system. A
sight glass is located on top of the filter drier. It is
used as a diagnostic tool to observe refrigerant flow.
HIGH PRESSURE RELIEF VALVE:The valve is
located on the filter drier. The valve is used to pre-
vent excessive high pressure build of 3445 to 4135
kPa (500 to 600 psi) and above. This prevents dam-
age to the compressor and other system components.
LOW-PRESSURE HIGH-PRESSURE CUT-OFF
SWITCH:The switch is located on the filter drier
and is wired in series with compressor clutch. When
the pressure drops down to 193 kPa (28 psi) the
switch interrupts the power to the compressor clutch.
When the pressure increases above 3100 to 3375 kPa
(450 to 490 psi) the switch interrupts the power to
the compressor clutch.
THERMOSTAT:The thermostat is located in the
evaporator housing. The thermostat temperature
sensing probe is inserted into the evaporator coil. Its
function is to cycles the compressor clutch on and off.
This switch controls temperature and prevents con-
densate water on the evaporator coil from freezing.
The thermostat is used on theYJonly.
REFRIGERANT LINES:The lines are used to
carry the refrigerant between the various system
components.
SERVICE PORTS:The high pressure service port
is located on the discharge line near the compressor.
The low pressure service port is located on the suc-
tion line near the compressor. These ports are used
to attach A/C gauges. After servicing the refrigerant
system, always install service port caps.
REFRIGERANT
XJ and YJ vehicles use a new type of refrigerant
called R-134a. It is a non-toxic, non-flammable, clear
color-less liquified gas.
R-134a refrigerant is not compatible with R-12 re-
frigerant. A small amount of R-12 in a R-134a system
will cause compressor failure, oil sludge or poor air
conditioning performance.R-134a refrigerant requires a special type of com-
pressor oil (SP20 PAG). When adding oil, make sure
that it is designed to be used in a R-134a system and
the SD7H15 compressor.
Service ports have been designed to ensure that
the system is not accidentally filled with R-12 refrig-
erant.
REFRIGERANT EQUIPMENT
WARNING: EYE PROTECTION MUST BE USED
WHEN SERVICING AN AIR CONDITIONING REFRIG-
ERANT SYSTEM. TURN OFF (ROTATE CLOCKWISE)
ALL VALVES ON THE EQUIPMENT BEING USED
BEFORE PROCEEDING WITH THIS OPERATION.
PERSONNEL INJURY CAN RESULT.
Chrysler Corporation recommends a (R-134a) recy-
cling device that meets SAE standard J2210 be used
when servicing the refrigerant system. Contact an
automotive service equipment supplier for refrigerant
recycling equipment that is available in your area.
Refer to the operating instructions provided with the
recycling equipment for proper operation.
MANIFOLD GAUGE SET
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.
A manifold gauge set (Fig. 1) may be needed in
conjunction with the charging and or recovery/recy-
cling device. 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 release into
the atmosphere.
LOW PRESSURE GAUGE HOSE
The low pressure hose (BLUE with BLACK STRIP)
should be attached to the charging/service port. This
port is located at the right front of the engine com-
partment in the condenser-to-evaporator line.
HIGH PRESSURE GAUGE HOSE
The high pressure hose (RED with BLACK STRIP)
should be attached to the discharge/service port. This
port is located on the compressor plumbing or mani-
fold.
RECOVERY/RECYCLING/EVACUATION/
CHARGING HOSE
The center manifold hose (YELLOW or WHITE
with BLACK STRIP) is used to recover, evacuate 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.
JHEATING AND AIR CONDITIONING 24 - 7

WARNINGS, CAUTIONS AND SERVICE PRECAUTIONS
WARNINGS
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.
WARNING: AVOID BREATHING A/C REFRIGERANT
AND LUBRICANT VAPOR OR MIST. EXPOSURE MAY
IRRITATE EYES, NOSE AND/OR THROAT. WEAR
EYE PROTECTION WHEN SERVICING THE AIR
CONDITIONING REFRIGERANT SYSTEM. SERIOUS
EYE INJURY CAN RESULT FROM EYE CONTACT
WITH REFRIGERANT. IF EYE CONTACT IS MADE,
SEEK MEDICAL ATTENTION IMMEDIATELY.
WARNING: DO NOT EXPOSE REFRIGERANT TO
OPEN FLAME. POISONOUS GAS IS CREATED
WHEN REFRIGERANT IS BURNED. AN ELEC-
TRONIC TYPE LEAK DETECTOR IS RECOM-
MENDED.
WARNING: IF ACCIDENTAL SYSTEM DISCHARGE
OCCURS, VENTILATE THE WORK AREA BEFORE
RESUMING SERVICE. LARGE AMOUNTS OF RE-
FRIGERANT RELEASED IN A CLOSED WORK AREA
WILL DISPLACE THE OXYGEN AND CAUSE SUFFO-
CATION.
WARNING: THE EVAPORATION RATE OF (R-134A)
REFRIGERANT AT AVERAGE TEMPERATURE AND
ALTITUDE IS EXTREMELY HIGH. AS A RESULT,
ANYTHING THAT COMES IN CONTACT WITH THE
REFRIGERANT WILL FREEZE. ALWAYS PROTECT
SKIN OR DELICATE OBJECTS FROM DIRECT CON-
TACT WITH REFRIGERANT.
WARNING: R-134A SERVICE EQUIPMENT OR VEHI-
CLE A/C SYSTEM SHOULD NOT BE PRESSURE
TESTED OR LEAK TESTED WITH COMPRESSED
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 EX-
PLOSION CAUSING INJURY OR PROPERTY DAM-
AGE.
CAUTIONS
CAUTION: Liquid refrigerant is corrosive to metal
surfaces. Follow the operating instructions supplied
with equipment being used.
CAUTION: DO NOT use R-12 equipment or parts on
the R-134a system. Damage to the system will re-
sult.
CAUTION: Never add R-12 to a system designed to
use R-134a. Damage to the system will result.
CAUTION: R-12 compressor oil can not be mixed
with the R-134a compressor oil. They ARE NOT
compatible.
CAUTION: Do not over charge refrigerant system.
This will cause excessive compressor head pres-
sure and can cause noise and system failure.
SERVICE PRECAUTIONS
Recover the refrigerant before opening any fitting
or connection. Open fittings with caution even after
the system has been discharged. Never open or
loosen a connection before recovering the refrigerant.
The A/C system must always be evacuated before
charging.
DO NOT open the refrigerant system or uncap a
replacement component until you are ready to service
the system. This will prevent contamination in the
system.
Before disconnecting a component clean the outside
of the fittings thoroughly to prevent contamination
entering the system.
Immediately after disconnecting a component from
the system, seal the open fittings with a cap or plug.
Before connecting an open fitting always install a
new seal/gasket. Coat the fitting and seal with clean
refrigerant oil before connecting.
When installing a refrigerant line avoid sharp
bends. Position the lines away from the exhaust or
any sharp edges which may chafe the line.
Tighten fittings only to the specified torque. The
aluminum fittings used in the A/C system will not
tolerate over tightening.
When disconnecting a fitting use a wrench on both
halves of the fitting. This will prevent twisting of the
refrigerant lines or tubes.
Refrigerant oil absorbs moisture from the atmo-
sphere if left uncapped. DO NOT open a container of
JHEATING AND AIR CONDITIONING 24 - 9

REFRIGERANT SERVICE AND PERFORMANCE TEST
INDEX
page page
Air Conditioning Performance Tests............ 12
Charging Refrigerant System................. 11
Evacuating Refrigerant System............... 11Leak Testing Refrigerant.................... 11
Recovering Refrigerant System............... 11
Refrigerant Oil........................... 12
LEAK TESTING REFRIGERANT
REVIEW WARNINGS AND CAUTIONS IN
THIS GROUP BEFORE LEAK TESTING.
If A/C system is not cooling properly, determine if
system is fully charged. Refer to Refrigerant System
Diagnosis Chart. If the system is empty evacuate the
A/C system and charge system with 0.283 kPa (0.6
lbs. or 10 oz.) R-134a refrigerant. Refer to Charging
Refrigerant System for instructions. To detect a leak
in the system, perform the following procedures.
(1) Position the vehicle in a wind free work area.
This will aid in detecting small leaks.
(2) Bring A/C system up to operating temperature
and pressure. This is done by allowing the engine to
run with the A/C on for 5 to 7 minutes.
(3) Open hood 5 minutes prior to leak test. This
will dissipate any accumulated refrigerant in the en-
gine compartment.
(4) With the engine not running, use an R-134a
Electronic Leak Detector and search for leaks. Move
probe slowly along the bottom side of lines and fit-
tings, because R-134a is heavier than air. Fittings,
lines, or components that appear to be oily usually
indicates a refrigerant leak.
(5) To inspect the evaporator core for leaks. Set the
blower at low speed and the selector in PANEL and
RECIRC mode check for leaks at CENTER panel out-
lets.
RECOVERING REFRIGERANT SYSTEM
REVIEW WARNINGS AND CAUTIONS IN
GENERAL INFORMATION SECTION OF THIS
GROUP BEFORE DISCHARGING SYSTEM.
R-134a refrigerant is a hydrofluorocarbon (HFC)
that does not contain chlorine. R-134a refrigerant Re-
covery/Recycling Station that meets SAE standard
J2210 must be used to recover the refrigerant. Refer
to the operating instructions provided with the equip-
ment for proper operation.
EVACUATING REFRIGERANT SYSTEM
REVIEW WARNINGS AND CAUTIONS IN
GENERAL INFORMATION SECTION OF THIS
GROUP BEFORE EVACUATING SYSTEM.
If the A/C system has been open to the atmosphere,
it must be evacuated before the system can be
charged. Moisture and air mixed with refrigerant will
raise the compressor head pressure above acceptable
operating levels. This will reduce the performance of
the air conditioner and damage the compressor. Mois-
ture will boil at near room temperature when ex-
posed to vacuum. To evacuate the refrigerant system
use following procedure:
(1) Connect a suitable charging station and mani-
fold gauge set to the vehicle.
(2) Open the low and high side valves and start
vacuum pump. When suction gauge reads 88 kPa (26
in. Hg) vacuum or greater, close all valves and turn
off vacuum pump. If system fails to reach specified
vacuum, the system has a leak that must be cor-
rected. If system maintains the specified vacuum for
30 minutes, start the vacuum pump. Then open the
suction and discharge valves and evacuate an addi-
tional 10 minutes.
(3) Close all valves. Turn off and disconnect the
vacuum pump.
The system is now ready to be charged with refrig-
erant.
CHARGING REFRIGERANT SYSTEM
REVIEW WARNINGS AND CAUTIONS IN
GENERAL INFORMATION SECTION OF THIS
GROUP BEFORE CHARGING SYSTEM.
After the system has been tested for leaks and
evacuated, a refrigerant charge can be injected into
the system. Refer to refrigerant capacities for proper
amount of refrigerant charge. Charge the system us-
ing a Recovery/Recycling/Charging Station approved
for R-134a refrigerant. Refer to the instructions pro-
vided with the equipment for proper operation.
REFRIGERANT CHARGE CAPACITY
The R-134a system charge capacity is 0.9 kPa (32
oz.) for XJ and YJ vehicles.
JHEATING AND AIR CONDITIONING 24 - 11