JEEP CHEROKEE 1988 Service Repair Manual
Page 151 of 1378
Alignment incorrect ..... B .. Require repair or replacement.
Application incorrect ... B ............ Require replacement.
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Bearing worn ............ 1 ............ Suggest replacement.
Belt tension incorrect .. B ... Require adjustment or repair.
Bracket cracked ......... A .. Require repair or replacement.
Housing cracked ......... A .. Require repair or replacement.
Missing ................. C ............ Require replacement.
Noisy ................... 2 ............ Suggest replacement.
Pulley damaged, affecting
belt life .............. A ............ Require replacement.
Seized .................. A .. Require repair or replacement.
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THERMISTORS AND PRESSURE SENSORS
NOTE: Includes, but not limited to, In-Car Temperature, Ambient
Air Temperature, Sun Load Sensor, etc.
THERMISTOR AND PRESSURE SENSOR INSPECTION
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Condition Code Procedure
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Calibration incorrect ... B .. Require repair or replacement.
Connector broken ........ A .. Require repair or replacement.
Connector (Weatherpack
type) leaking .......... A .. Require repair or replacement.
Connector melted,
affecting performance .. A ........... ( 1) Require repair or
replacement.
Connector melted, not
affecting performance .. 2 ........... ( 1) Suggest repair or
replacement.
Connector missing ....... C ............ Require replacement.
Inoperative ............. A ........... ( 2) Require repair or
replacement.
Missing ................. C ............ Require replacement.
Terminal burned, affecting
performance ............ A ........... ( 1) Require repair or
replacement.
Terminal burned, not
affecting performance ... 2 .. Suggest repair or replacement.
Terminal corroded,
affecting performance .. A .. Require repair or replacement.
Terminal corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
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Terminal loose, affecting
performance ............ B .. Require repair or replacement.
Terminal loose, not
affecting performance .. 1 .. Suggest repair or replacement.
Wire lead burned ........ A .. Require repair or replacement.
Wire lead conductors
exposed ................ B .. Require repair or replacement.
Wire lead open .......... A .. Require repair or replacement.
Wire lead shorted ....... A .. Require repair or replacement.
(1) - Determine cause and correct prior to repair or
replacement of part.
( 2) - Inoperative includes intermittent operation or out of
OEM specification.
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THERMOSTATS AND HOUSINGS
THERMOSTAT AND HOUSING INSPECTION \
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Condition Code Procedure
Application incorrect ... B ............ Require replacement.
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
corroded ................ A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Cracked ................. A ............ Require replacement.
Housing corroded ........ 1 .......... Suggest replacement of
housing.
Inoperative ............. A ........ ( 1) Require replacement.
Installation incorrect .. B .. Require repair or replacement.
Leaking ................. A .. Require repair or replacement.
Thermostat missing ...... C .......... Require replacement of
thermostat.
Threads damaged ......... A .. Require repair or replacement.
Threads stripped (threads
missing) ............... A .. Require repair or replacement.
( 1) - Inoperative includes intermittent operation or out of
OEM specification.
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VACUUM HOSES AND TUBES
VACUUM HOSE AND TUBE INSPECTION \
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Condition Code Procedure
Disconnected ............ A ................. Require repair.
Leaking ................. A .. Require repair or replacement.
Melted .................. A ..... Require repair replacement.
Missing ................. C ............ Require replacement.
Oil-soaked (spongy) ..... 1 ............ Suggest replacement.
Restricted .............. A .. Require repair or replacement.
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Routing incorrect ....... B ................. Require repair.
Surface cracks (dry-
rotted) ................ 1 ............ Suggest replacement.
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VACUUM RESERVOIRS
VACUUM RESERVOIR INSPECTION \
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Condition Code Procedure
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Check valve leaking
internally ............. A ............ Require replacement.
Leaking ................. A .. Require repair or replacement.
Missing ................. C ............ Require replacement.
Restricted .............. A .. Require repair or replacement.
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VACUUM TUBES
See VACUUM HOSES AND TUBES .
VALVES IN RECEIVER (VIRS)
VALVE IN RECEIVER (VIR) INSPECTION \
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Condition Code Procedure
Application incorrect ... B ............ Require replacement.
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Bracket bent, affecting
performance ............ A .. Require repair or replacement.
Bracket bent, not
affecting performance .. .. ........ No service suggested or
required.
Bracket broken, affecting
performance ............ A ............ Require replacement.
Bracket broken, not
affecting performance .. .. ........ No service suggested or
required.
Bracket corroded,
affecting performance .. A .. Require repair or replacement.
Bracket corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
Bracket cracked, affecting
performance ............ A .. Require repair or replacement.
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Bracket cracked, not
affecting performance .. 1 .. Suggest repair or replacement.
Bracket holes elongated,
affecting performance .. A .. Require repair or replacement.
Bracket holes elongated,
not affecting
performance ............ .. ........ No service suggested or
required.
Bracket loose, affecting
performance ............ A .. Require repair or replacement.
Bracket loose, not
affecting performance .. 1 .. Suggest repair or replacement.
Bracket missing ......... C ............ Require replacement.
Connection damaged ...... B .. Require repair or replacement.
Contaminated, affecting
performance ............ A ............ Require replacement.
Corroded internally ..... 1 ............ Suggest replacement.
Dessicant bag
deteriorated ........... A ........ (1) Require replacement.
Further inspection required.
Dessicant at the end of
its useful life
(saturated
with moisture) ......... 1 .. Suggest repair or replacement.
Filter screen torn ...... A .. Require replacement of screen.
Fitting damaged ......... B .. Require repair or replacement.
Fusible plug leaking .... A .... Require replacement of plug.
Inoperative ............. A ........... ( 2) Require repair or
replacement.
Leaking ................. A .. Require repair or replacement.
Pressure relief device
leaking ................ A . Require replacement of pressure
relief device.
Restricted .............. A .. Require repair or replacement.
Sight glass no longer
transparent ............ 2 ... Suggest replacement of drier.
Threads damaged ......... A .. Require repair or replacement.
Threads stripped (threads
missing) ............... A ............ Require replacement.
Tubing connection
leaking ................ A .. Require repair or replacement.
( 1) - Inspect system to determine effects of dessicant bag
deterioration.
( 2) - Inoperative includes intermittent operation or out of
OEM specification.
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WATER PUMPS (ELECTRIC AUXILIARY)
WATER PUMP (ELECTRIC AUXILIARY) INSPECTION \
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Condition Code Procedure
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
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Connector broken ........ A .. Require repair or replacement.
Connector (Weatherpack
type) leaking .......... A .. Require repair or replacement.
Connector melted,
affecting performance .. A ........... (1) Require repair or
replacement.
Connector melted, not
affecting performance .. 2 ........... ( 1) Suggest repair or
replacement.
Connector missing ....... C ............ Require replacement.
Inoperative ............. A ........ ( 2) Require replacement.
Leaking ................. A .. Require repair or replacement.
Missing ................. C ............ Require replacement.
Noisy ................... 2 ............ Suggest replacement.
Terminal broken ......... A .. Require repair or replacement.
Terminal burned, affecting
performance ............ A ........... ( 1) Require repair or
replacement.
Terminal burned, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal corroded,
affecting performance .. A .. Require repair or replacement.
Terminal corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal loose, affecting
performance ............ B .. Require repair or replacement.
Terminal loose, not
affecting performance .. 1 .. Suggest repair or replacement.
Vibration ............... 1 .. Suggest replacement.
Wire lead conductors
exposed ................ B .. Require repair or replacement.
Wire lead corroded ...... A .. Require repair or replacement.
Wire lead open .......... A .. Require repair or replacement.
Wire lead shorted ....... A .. Require repair or replacement.
( 1) - Determine cause and correct prior to repair or
replacement of part.
( 2) - Inoperative includes intermittent operation or out of
OEM specification.
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WIRING HARNESSES AND CONNECTORS
WIRING HARNESS AND CONNECTOR INSPECTION \
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Condition Code Procedure
Application incorrect ... B .. Require repair or replacement.
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Connector broken ........ A .. Require repair or replacement.
Connector (Weatherpack
type) leaking .......... A .. Require repair or replacement.
Circuit open ............ A .. Require repair or replacement.
Circuit resistance
(voltage drop) out of
Page 156 of 1378
specification .......... A .. Require repair or replacement.
Circuit shorted ......... A .. Require repair or replacement.
Connector melted,
affecting performance .. A ........... (1) Require repair or
replacement.
Connector melted, not
affecting performance .. 2 ........... ( 1) Suggest repair or
replacement.
Connector missing ....... C ............ Require replacement.
Diode open .............. A .. Require repair or replacement.
Diode shorted ........... A .. Require repair or replacement.
Insulation damaged,
conductors exposed ..... A .. Require repair or replacement.
Insulation damaged,
conductors not exposed . 1 ............ Suggest replacement.
Protective shield
(conduit) melted ....... B ........ ( 1) Require replacement.
Protective shield
(conduit) missing ...... C ............ Require replacement.
Routed incorrectly ...... B ................. Require repair.
Secured incorrectly ..... B ................. Require repair.
Terminal broken ......... A .. Require repair or replacement.
Terminal burned, affecting
performance ............ A ........... ( 1) Require repair or
replacement.
Terminal burned, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal corroded,
affecting performance .. A .. Require repair or replacement.
Terminal corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal loose, affecting
performance ............ B .. Require repair or replacement.
Terminal loose, not
affecting performance .. 1 .. Suggest repair or replacement.
Voltage drop out of
specification .......... A .. Require repair or replacement.
( 1) - Determine cause and correct prior to repair or
replacement of part.
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\003
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 159 of 1378
* Expansion Dry Frosty-Check for moisture or
Valve restriction. Check sensing
bulb.
* STV Dry and cool to Frosty or warm-Check gauge
touch. readings for valve malfunction
* Evaporator Dry and cold to Freezing or warm-Check
touch. expansion valve, STV or thermo
switch.
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Gauge Readings Gauge Readings are
* High Side See Pressure Above or below normal-See A/C
Gauge Chart Diagnosis on next page.
* Low Side See Pressure Above or below normal-See A/C
Gauge Chart Diagnosis on next page.
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Fig. 1: AMBIENT TEMPERATURE/PRESSURE
Page 160 of 1378
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.