1988 JEEP CHEROKEE air conditioning
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METAL FITTINGS
See
AIR CONDITIONING METAL LINES, HOSES AND FITTING ASSEMBLIES .
METAL LINES
See
AIR CONDITIONING METAL LINES, HOSES AND FITTING ASSEMBLIES .
MIX AND AIR CONTROL DOORS (BLEND DOORS)
See PLENUMS.
O-RINGS
O-RING INSPECTION \
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Condition Code Procedure
Leaking ................. A ........... ( 1) Require repair or
replacement.
( 1) - Require inspection of mating and sealing surface and
repair or replace as necessary.
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ORIFICE TUBES
ORIFICE TUBE INSPECTION \
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Condition Code Procedure
Application incorrect ... B ............ Require replacement.
Bypassing internally .... A .. Require repair or replacement.
Filter screen torn ...... A ............ Require replacement.
Installation incorrect .. B ................. Require repair.
Restricted .............. A .. Require repair or replacement.
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PILOT-OPERATED ABSOLUTES (POAS)
PILOT-OPERATED ABSOLUTE (POA) INSPECTION \
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Condition Code Procedure
Connection damaged ...... B .. Require repair or replacement.
Fitting damaged ......... B .. Require repair or replacement.
Inoperative ............. A ........... ( 1) Require repair or
replacement.
Leaking ................. A .. Require repair or replacement.
Threads damaged ......... A .. Require repair or replacement.
Threads stripped (threads
missing) ............... A ............ Require replacement.
( 1) - Inoperative includes intermittent operation or out of
OEM specification.
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PLENUMS
PLENUM INSPECTION
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A/C S YSTE M D IA G NO SIS
1988 J e ep C hero ke e
1988 AIR CONDITIONING & HEAT
A/C General Servicing
Diagnostic Procedures
Jeep; All Models
DIAGNOSTIC PROCEDURES
Diagnosis is an important first step in A/C system servicing.
To save time and effort, systems should be carefully checked to
identify the causes of poor performance. By using the following
diagnostic charts, defective components or system damage can be
quickly located. To identify problems that are specific to one system,
refer to the repair section of this manual. The charts in this section
apply to all systems.
PREPARATION FOR TESTING
1) Attach Low and High side gauges.
2) Start engine and allow it to warm up.
3) Set system to COOL and blower to HIGH.
4) Open car doors and hood.
5) Run at fast idle for 2-3 minutes.
ALTITUDE PRESSURE VARIATIONS TABLE
ALTITUDE PRESSURE VARIATIONS TABLE \
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Altitude Absolute Gauge Altitude
(Ft.Above Pressure Of Correction
Sea Level) Atmosphere (psi) (1) (psi)
0 .......................... 14.7 .............................. 0
1000 ....................... 14.2 ............................ 0.5
2000 ....................... 13.7 ............................ 1.0
3000 ....................... 13.2 ............................ 1.5
4000 ....................... 12.7 ............................ 2.0
5000 ....................... 12.2 ............................ 2.5
6000 ....................... 11.7 ............................ 3.0
7000 ....................... 11.3 ............................ 3.4
8000 ....................... 10.9 ............................ 3.8
9000 ....................... 10.5 ............................ 4.2
10,000 ..................... 10.1 ............................ 4.6
( 1) - Add correction shown from gauge readings
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ALTITUDE VACUUM VARIATIONS TABLE
ALTITUDE VACUUM VARIATIONS TABLE \
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Altitude Complete Gauge Altitude
(Ft.Above Vacuum Correction
Sea Level) (In. Hg) (1) (In. Hg)
0 .......................... 29.92 ............................. 0
1000 ....................... 28.92 ........................... 1.0
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2000 ....................... 27.82 ........................... 2.1
3000 ....................... 26.82 ........................... 3.1
4000 ....................... 25.82 ........................... 4.1
5000 ....................... 24.92 ........................... 5.0
6000 ....................... 23.92 ........................... 6.0
7000 ....................... 23.02 ........................... 6.9
8000 ....................... 22.22 ........................... 7.7
9000 ....................... 21.32 ........................... 8.6
10,000 ..................... 20.52 ........................... 9.4
(1) - Add correction shown to gauge readings
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OPERATIONAL TEST GAUGE READINGS
Normal System Operating Pressures (PSI) ( 1)
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Low Side High Side
Gauge Gauge
Application (Suct.) (Disc.\
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Jeep 1980-87
(Thermostatic Switch) ........ 5-24 ................... 208-250\
1988
(Accumulator Type) ........... 24-50 .................. 160-250\
( 1) - Pressure readings given are for a system in good operating
condition, at sea level and an ambient temperature of 80
F
(27C). \
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AIR CONDITIONING SYSTEM PERFORMANCE CHECK TABLE \
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PERFORM TESTS: SHOULD BE: IF: \
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Temperature Check Temperature Check is
* Switch to LOW
blower
* Close doors Too warm-Check control lever
* Check outlet 35-45
F (1.7-7.2C) operation, heater water valve,
temperature. cooling system and gauge
readings.
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Visual Check Visual Check Shows:
* Compressor Quiet, no leaks Noisy-Check belts, oil level,
seals, gaskets, reed valves.
* Condenser Free of Blocked-Clean off. Plugged-
obstructions Flush or replace.
* Receiver- Dry and warm to Frosty-Check for restriction,
Drier touch. replace desiccant.
* Sight Glass Clear or few Bubbly, foamy or streaks-
bubbles Check gauge readings.
* High Side Dry and warm to Frosty or very hot-Check for
touch. restriction or overcharge.
* Low Side Dry and cool to Frosty or warm-Check for
Lines touch. restriction, low charge or
bad valve.
Page 160 of 1378
![JEEP CHEROKEE 1988 Service Repair Manual Fig. 2: EVAPORATOR TEMPERATURE/PRESSURE
AIR CONDITIONING DIAGNOSIS WITH GAUGES FOR SYSTEMS WITH
INSUFFICIENT OR NO COOLING
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\](/manual-img/16/57037/w960_57037-159.png "JEEP CHEROKEE 1988 Service Repair Manual Fig. 2: EVAPORATOR TEMPERATURE/PRESSURE
AIR CONDITIONING DIAGNOSIS WITH GAUGES FOR SYSTEMS WITH
INSUFFICIENT OR NO COOLING
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Fig. 2: EVAPORATOR TEMPERATURE/PRESSURE
AIR CONDITIONING DIAGNOSIS WITH GAUGES FOR SYSTEMS WITH
INSUFFICIENT OR NO COOLING
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LOW SIDE HIGH SIDE OTHER SYMPTOMS (1) DIAGNOSIS
GAUGE GAUGE
Normal Normal No or few bubbles in sight Some Air and
glass. High side gauge may Moisture in System.
go high. Low side gauge
does not fluctuate with
compressor on/off cycle.
Normal Normal Cools okay in morning but Excessive Moisture
not during hot part of day.
Tiny bubbles in sight glass.
Page 162 of 1378
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A/C S YSTE M G EN ER AL S ER VIC IN G
1988 J e ep C hero ke e
1988 AIR CONDITIONING & HEAT
A/C General Servicing
Diagnostic Procedures
Eagle & Jeep
* PLEASE READ THIS FIRST *
CAUTION: When discharging air conditioning system, use only approved
refrigerant recovery/recycling equipment. Make every attempt
to avoid discharging refrigerant into the atmosphere.
INTRODUCTION
This article is to be used for general service and diagnosis.
For specific repair or replacement procedures, use the appropriate
repair article in this section.
R-12 REFRIGERANT - SAFETY PRECAUTIONS
1) Always work in a well-ventilated, clean area. Refrigerant
(R-12) is heavier than oxygen, and will displace oxygen in a confined
area. Always wear eye protection when working around air conditioning
systems and R-12. The system's high pressure can cause severe injury
to eyes and skin if a hose were to burst. R-12 evaporates quickly
when exposed to atmosphere, freezing anything it contacts.
2) Use care when handling refrigerant containers. Do not
drop or strike containers. Do not expose refrigerant containers to
excessive heat. Containers must never be heated more than 125
F.
Never expose R-12 directly to open flame.
CAUTION: When R-12 is exposed to an open flame, drawn into a running
engine, or detected with a Halide (propane) leak tester,
poisonous phosgene gas is formed. Keep work areas
ventilated and keep vehicles with running engines away.
USING INDIVIDUAL R-12 CANS
Disposable refrigerant cans (referred to as one pound cans)
have a flat type seal or a screw type seal, and the proper can tap
must be used for each type. Be sure sealing gasket on can tap is in
good condition. A proper safety can tap will prevent refrigerant from
flowing back into open can, as the tap has a one-way flow control.
NOTE: Recent findings by the EPA indicate that R-11, R-12 and
R-113 are harmful to the Earths' protective Ozone layer.
Make every attempt possible, to avoid discharging R-11, R-12
or R-113 into the atmosphere.
USING MULTI-CAN DISPENSING VALVES
A multi-can dispensing valve allows the attachment of
several cans of refrigerant, and is a good substitute when a bulk
container is not available. Cans are installed onto each leg of the
multi-can dispensing valve in the same manner as the individual cans,
and each leg has its own can tap.
Page 163 of 1378
CAN TAP INSTALLATION
FLAT TYPE SEAL CANS
On cam-lock or one-piece can taps, first turn the handle out
to the fully open position. Securely engage the locking lugs over the
flange of the can, and lock them in place by turning the cam lock or
locking nut. Screw the tap assembly into the adapter so the sealing
gasket is fully seated against the can top. Turn the tap inward to
pierce the can and close the tap. DO NOT open the tap until ready to
purge the service hose or dispense refrigerant into the system.
On 2-piece can taps, be certain the tap handle is turned
fully in, so it is closed. Check that the locking base is turned to
its outer limit. Securely engage the locking lugs over the can
flange. Turn the entire tap assembly (without disturbing the closed
setting) down into the locking base to pierce the can. Do not open
the tap until ready to dispense into system.
SCREW TYPE SEAL CANS
Ensure can tap is fully closed. Screw refrigerant can into
can tap fitting until tight. This will pierce the can. Connect tap to
center hose on manifold gauge set. DO NOT open tap until ready to
dispense R-12 into system.
WARNING: DO NOT open high side hand valve while air conditioning
system is in operation. This high pressure could rupture
can or possibly burst fitting at safety can valve,
resulting in damage and physical injury.
COMPRESSOR OIL CHECK
GENERAL PROCEDURES
Some models have compressor-mounted service valves that allow
oil checking by isolating the compressor. On all others, system must
be discharged, using approved refrigerant recovery/recycling
equipment, and compressor may need to be removed to check oil. After
oil level is checked and adjusted, A/C system must be evacuated and
recharged.
ISOLATING COMPRESSOR
1) Connect manifold gauge set to service valves on the
compressor. Close both gauge valves. Open both service valves to
themid-position.
2) Start engine and operate air conditioning. Turn suction
service valve slowly clockwise toward front-seated position. When
suction pressure is reduced to zero or less, stop engine and quickly
close suction service valve (front-seated).
3) Front-seat the discharge valve. Loosen oil check plug
slowly to release any internal pressure. Service valves can now be
removed from compressor and compressor removed from vehicle (if
necessary). Purge compressor after servicing.
PURGING COMPRESSOR
1) Remove gauge set and place caps on service valve ports.
Back-seat the suction service valve to allow refrigerant to enter
compressor.
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2) Loosen discharge port valve slightly. Loosen valve port
cap to allow refrigerant to force out air from compressor. Back-seat
the discharge valve and tighten the port cap. Compressor is ready for
service.
REFRIGERATION OIL
Only new, pure, moisture-free refrigeration oil should be
used in the air conditioning system. This oil is highly refined and
dehydrated (moisture content less than 10 parts per million).
Refrigeration oil container must be kept tightly closed at
all times when not in use, or moisture will be absorbed from the air
and introduced into the refrigeration system.
NIPPONDENSO 10-CYLINDER
SHAFT SEAL
NOTE: Check compressor refrigerant oil level when replacing seals.
See COMPRESSOR REFRIGERANT OIL CHECKING article in this
section.
Removal
1) Hold clutch hub stationary and remove center nut. Screw
remover into center of hub. Turn center bolt to remove pressure plate.
2) Remove shims from shaft. Remove snap ring from inside of
pulley. Tap pulley off of shaft with plastic mallet. Be careful not
to distort pulley while removing.
3) Disconnect clutch coil wires from compressor housing.
Remove snap ring inside coil and lift coil off compressor. Pry dust
seal out from around compressor shaft (if equipped).
4) Place shaft key remover on shaft and turn to remove key.
Remove drain plug (if equipped). Remove bolts holding service valves
to body of compressor and remove valves. Discard "O" rings. Drain oil
out of compressor.
5) Remove 6 through bolts from front head of compressor and
discard washers. Tap head loose from compressor, being careful not to
scratch sealing surfaces. Remove snap ring (if equipped) from front
housing. Press seal plate out. Remove seal from shaft. See Fig. 1.
Installation
1) Lubricate shaft seal with clean refrigerant oil. Place on
compressor shaft. Lubricate seal plate (and "O" ring, if equipped) and\
install in front housing. Install snap ring (if equipped).
2) Place front housing on compressor body. Using new
washers, install through bolts. Tighten bolts evenly and alternately
to 18 ft. lbs. (24 N.m). Install shaft key with installer and plastic
mallet. Insert dust seal into front of compressor.
3) Install drain plug using new gasket. Add correct amount
of refrigerant oil to compressor. If service valves were removed,
coat new "O" rings with refrigerant oil and install service valves.
4) Place clutch coil on compressor and install snap ring.
Install shims on shaft to adjust clearance between pressure plate and
rotor to .016-.028" (.41-.71 mm). Tighten shaft nut to 12 ft. lbs. (1\
6
N.m). See REFRIGERANT OIL & R-12 SPECIFICATIONS table for system
capacities.
SANKYO/SANDEN 5-CYLINDER COMPRESSOR SERVICING
NOTE: During the past year, Sankyo International (USA), Inc. has
changed its name to Sanden International (USA), Inc.
Page 167 of 1378
Isolating Compressor
1) Connect manifold gauge set to service valves on
compressor. Close both gauge valves. Open both service valves to the
mid-position.
2) Start engine and operate air conditioning. Turn suction
service valve slowly clockwise toward front-seated position. When
suction pressure is reduced to zero or less, stop engine and quickly
close suction service valve (front-seated).
3) Front-seat the discharge valve. Loosen oil check plug
slowly to release any internal pressure. Service valves can now be
removed from compressor and compressor removed from vehicle (if
necessary). Purge compressor after servicing.
Purging Compressor
1) Remove gauge set and place caps on service valve ports.
Back-seat the suction service valve to allow refrigerant to enter
compressor.
2) Loosen discharge port valve slightly. Loosen valve port
cap to allow refrigerant to force out air from compressor. Back-seat
the discharge valve and tighten the port cap. Compressor is ready for
service.
Compressor Oil Check
1) Operate system for 10 minutes, then stop and isolate
compressor. Loosen filler plug slowly to release any pressure in
crankcase.
2) Use dipstick to check oil level. See Fig. 2. Add oil as
necessary. Install plug with new "O" ring. Purge compressor of air.
Fig. 2: York Compressor Oil Level Dipstick
Check oil with shaft keyway facing head.
SYSTEM SERVICING CAUTIONS