1988 JEEP CHEROKEE lock
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Application incorrect,
affecting air
conditioning
system performance ..... A .. 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.
Bent, affecting air
conditioning system
performance ............ A .. Require repair or replacement.
Blocked, affecting air
conditioning system
performance ............ A .. Require repair or replacement.
Broken, affecting air
conditioning system
performance ............ A .. Require repair or replacement.
Cracked, affecting air
conditioning system
performance ............ A .. Require repair or replacement.
Loose, affecting air
conditioning system
performance ............ A ................. Require repair.
Loose, not affecting air
conditioning system
performance ............ 2 ................. Suggest repair.
Missing, affecting air
conditioning system
performance ............ C ............ Require replacement.
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AIR DISTRIBUTION SYSTEM
See PLENUMS.
BELTS
BELT INSPECTION \
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Condition Code Procedure
Alignment incorrect ..... B .......... ( 1) Further inspection
required.
Cracked ................. 1 ............ Suggest replacement.
Frayed .................. 1 ............ Suggest replacement.
Missing ................. C ............ Require replacement.
Noisy ................... 2 .......... ( 2) Further inspection
required.
Plies separated ......... A ............ Require replacement.
Serpentine belt routed
incorrectly ............ B ................. Require repair.
Tension out of
specification .......... B ........... Require adjustment or
replacement.
Worn beyond
adjustment range ....... B ............ Require replacement.
Page 149 of 1378
![JEEP CHEROKEE 1988 Service Repair Manual SERVICE PORT INSPECTION \
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Condition Code](/manual-img/16/57037/w960_57037-148.png "JEEP CHEROKEE 1988 Service Repair Manual SERVICE PORT INSPECTION \
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Condition Code")
SERVICE PORT INSPECTION \
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Condition Code Procedure
Application
does not match
refrigerant type ....... B ............ Require replacement.
Leaking ................. A .. Require repair or replacement.
Threads damaged ......... A .. Require repair or replacement.
Threads stripped (threads
missing) ............... A ............ Require replacement.
Valve cap leaking ....... A ... Require repair or replacement
of cap.
Valve cap missing ....... C .... Require replacement of valve
cap.
Valve core sticking ..... B .. Require repair or replacement.
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SPRING LOCK COUPLINGS
SPRING LOCK COUPLING 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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SUCTION THROTTLING VALVES (STVS)
SUCTION THROTTLING VALVE (STV) 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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SWITCHES (ELECTRICAL)
SWITCH (ELECTRICAL) 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.
Page 158 of 1378
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 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.
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
Page 171 of 1378
* Switch to LOW
blower.
* Close doors. Too warm - Check control
lever operation, heater
water valve, cooling
system and gauge readings.
* Check outlet
temperature. 35-45
F (1.7-7.2 C)\
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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 Obstructions Blocked - Clean off.
Plugged - Flush or
replace.
* Receiver-Drier Dry and warm to Frosty - Check for re-
touch striction, replace
Desicant.
* Sight Glass Clear or few bubbles Bubbly, foamy or streaks -
Check gauge readings.
* High Side Lines Dry and warm to Frosty or very hot - Check
touch for restriction or
overcharge.
* Low Side Lines Dry and cool to Frosty or warm - Check for
touch restriction, low charge or
bad valve.
* Expansion Valve Dry Frosty - Check for moisture
or restriction. Check
sensing bulb.
* STV Dry and cool to Frosty or warm - Check
touch gauge 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 Gauge See Pressure Chart Above or below normal - See
A/C DIAGNOSIS.
* Low Side Gauge See Pressure Chart Above or below normal - See
A/C DIAGNOSIS.
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PRESSURE CHARTS
Page 179 of 1378
TESTING
VACUUM MOTOR & TEMPERATURE SENSOR
1) Remove air cleaner assembly from vehicle and allow to
cool to room temperature. Look through air cleaner duct and observe
position of air diverter valve. It should be fully open to outside
air.
2) Reinstall assembly on carburetor and connect hot air duct
and manifold vacuum hose. Start engine and observe position of air
valve in snorkel. It should be fully closed to outside air.
3) Move throttle lever rapidly to 1/2 to 3/4 opening and
release. Air diverter valve should open and then close again. Allow
engine to warm to operating temperature and observe position of air
valve in snorkel. It should be fully open to outside air.
4) If valve does not move to fully close off outside air at
83
F (28 C) or less with vacuum applied, check for binding of duct,
vacuum leaks in hose connections or disconnected vacuum motor. If
valve mechanism operates freely and no vacuum leaks are detected,
connect hose from intake manifold vacuum source directly to vacuum
motor.
5) If air valve now moves to close off outside air, replace
thermal sensor switch. If valve still does not move to close off
outside air, replace air cleaner assembly and vacuum motor assembly.
TRAP DOOR
1) With engine off, remove air cleaner and check position of
trap door. It should be closed.
2) Remove vacuum hose from intake manifold vacuum source and
apply an external vacuum source of approximately 2-4 in. Hg vacuum.
Trap door should open.
3) If door does not open, apply vacuum directly to vacuum
motor. If door does not open, check for binding and adjust as
necessary. If door swings freely, replace vacuum motor.
4) If door opens during step 3), check vacuum hose for
blockage, cracks or leaks. Correct as necessary and retest as
specified in step 2).
5) If hoses are not defective, remove reverse delay valve,
join vacuum hose and retest from step 2). If door opens, replace
reverse delay valve.
REVERSE DELAY VALVE
1) Connect external vacuum source to port on White side of
delay valve. Connect one end of 24" (610 mm) section of rubber hose
to vacuum gauge and other end to port on colored side of valve.
2) With a constant 10 in. Hg vacuum applied, note time
required for vacuum gauge pointer to move from 0-8 in. Hg.
Page 192 of 1378
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AN TI- L O CK B RAK E S A FE TY P R EC AU TIO NS
1988 J e ep C hero ke e
GENERAL INFORMATION
Anti-Lock Brake Safety Precautions
* PLEASE READ THIS FIRST *
This article is intended for general information purposes
only. This information may not apply to all makes and models. If
vehicle is equipped with Anti-Lock Brake System (ABS), refer to
appropriate ANTI-LOCK BRAKE SYSTEM article in the BRAKES section for
description, operation, depressurizing, testing, system bleeding,
trouble shooting and servicing of specific system.
WARNING: Failure to depressurize ABS could lead to physical injury.
ANTI-LOCK BRAKE SAFETY PRECAUTIONS
WARNING: Failure to depressurize ABS could lead to physical injury.
* NEVER open a bleeder valve or loosen a hydraulic line
while ABS is pressurized.
* NEVER disconnect or reconnect any electrical connectors
while ignition is on. Damage to ABS control unit may result.
* DO NOT attempt to bleed hyudarulic system without first
referring to the appropriate ANTI-LOCK BRAKE SYSTEM article
in the BRAKES section.
* Only use specially designed brake hoses/lines on ABS equipped
vehicles.
* DO NOT tap on speed sensor components (sensor, sensor rings).
Sensor rings must be pressed into hubs, NOT hammered into
hubs. Striking these components can cause demagnetization or
a loss of polarization, affecting the accuracy of the speed
signal returning to the ABS control unit.
* DO NOT mix tire sizes. Increasing the width, as long as tires
remain close to the original diameter, is acceptable. Rolling
diameter must be identical for all 4 tires. Some
manufacturers recommend tires of the same brand, style and
type. Failure to follow this precaution may cause inaccurate
wheel speed readings.
* DO NOT contaminate speed sensor components with grease. Only
use recommended coating, when system calls for an
anti-corrosion coating.
* When speed sensor components have been removed, ALWAYS check
sensor-to-ring air gaps when applicable. These specifications
can be found in each appropriate article.
* ONLY use rocommended brake fluids. DO NOT use silicone brake
fluids in an ABS equipped vehicle.
* When instlling transmittion devices (CB's, telephones, etc.)
on ABS equipped vehicles, DO NOT locate the antenna near the
ABS control unit (or any control unit).
* Disconnect all on-board computers, when using electric
welding equipment.
* DO NOT expose the ABS control unit to prolonged periods of
high heat (185
F/85 C for 2 hours is generally considered a
maximum limit).