light JEEP CHEROKEE 1988 Service User Guide
[x] Cancel search | Manufacturer: JEEP, Model Year: 1988, Model line: CHEROKEE, Model: JEEP CHEROKEE 1988Pages: 1378, PDF Size: 19.9 MB
Page 96 of 1378
mm Millimeters
M/T Manual Transaxle or Transmission
MA PFI Mass Air Sequential Port Fuel Injection system
MA or MAF Mass Airflow
MAF Mass Air Flow sensor
MAFS Mass Airflow Sensor
MAP Manifold Absolute Pressure sensor
MAT Manifold Air Temperature
MCU Microprocessor Control Unit
MCV Mixture Control Valve
MEM-CAL Memory Calibration Chip
MFI Multiport Fuel Injection
MIL Malfunction Indicator Light
MLP Manual Lever Position
MPFI Multi Point Fuel Injection
MPH Miles Per Hour
MPI Multi-Point (Fuel) Injection
Man. Manual
Mech. Mechanical
Mem. Memory
Mtr. Motor
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"N" ABBREVIATION TABLE
"N" ABBREVIATION TABLE \
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ABBREVIATION DEFINITION
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N.m Newton-Meter
NA Not Available
NDS Neutral Drive Switch
NGS Neutral Gear Switch
NOx Oxides of Nitrogen
NPS Neutral Pressure Switch
No. Number
Nos. Numbers
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"O" ABBREVIATION TABLE
"O" ABBREVIATION TABLE \
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O Oxygen
O.D. Outside Diameter
O/S Oversize
O2 Oxygen
OC Oxidation Catalyst
OCC Output Circuit Check
OD Overdrive
ODO Odometer
OHC Overhead Camshaft
ORG Orange
OSC Output State Check
Opt. Option or Optional
oz. Ounce
ozs. Ounces
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RVB Rear Vacuum Break
RWAL Rear Wheel Anti-Lock Brake
RWD Rear Wheel Drive
Recirc. Recirculate or Recirculation
Reg. Regulator
Rly. Relay
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"S" ABBREVIATION TABLE
"S" ABBREVIATION TABLE \
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ABBREVIATION DEFINITION
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SAW Spark Angle Word
SBC Single Bed Converter
SBEC Single Board Engine Controller
SC Super Charged
SCC Spark Control Computer
SCS Air Suction Control Solenoid
SDM Supplemental Restraint System Diagnostic Module
SDU SRS Diagnostic Unit
SEN Sensor
SES Service Engine Soon
SFI Sequential (Port) Fuel Injection
SIG RTN Signal Return circuit
SIL Shift Indicator Light
SIR Supplemental Inflatable Restraint
SMEC Single Module Engine Controller
SOHC Single Overhead Cam
SOL or Sol. Solenoid
SPFI Sequential Port Fuel Injection
SPK Spark Control
SPOUT Spark Output Signal
SRS Supplemental Restraint System (Air Bag)
SS 3/4-4/3 Shift Solenoid circuit
SSI Solid State Ignition
STAR Self-Test Automatic Readout
STI Self Test Input circuit
STO Self-Test Output
SUB-O2 Sub Oxygen Sensor
Sen. or Sens. Sensor
Sol. Solenoid
Sprchg. Supercharger
Strg. Steering
Susp. Suspension
Sw. Switch
Sys. System
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"T" ABBREVIATION TABLE
"T" ABBREVIATION TABLE \
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ABBREVIATION DEFINITION
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T.V. Throttle Valve
TAB Thermactor Air By-Pass
TAC Thermostatic Air Cleaner
TAD Thermactor Air Diverter
TAN Tan
TBI Throttle Body Injection
Page 101 of 1378
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A/C C O M PR ESSO R O IL C HEC KIN G
1988 J e ep C hero ke e
A/C General Servicing
COMPRESSOR OIL CHECK
* 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.
ISOLATING COMPRESSOR - GRAND WAGONEER ONLY
1) Connect service gauge set to the compressor service valves
and open compressor valves slightly (turn clockwise). Start engine and\
operate air conditioning. Slowly turn compressor suction valve
clockwise toward closed (front-seated) position.
2) When suction pressure is reduced to zero or less, turn off
engine and compressor and quickly turn suction valve stem in to full
front-seated position. Suction pressure should be slightly above zero.
Turn discharge valve into front-seated position.
3) To check oil lever, slowly open crankcase plug to relieve
any remaining pressure. After oil level is correct, cap service gauge
parts on both valves. Back-seat suction service valve to allow
refrigerant to enter compressor. Open discharge valve halfway.
4) Loosen discharge service valve cap, allowing refrigerant
pressure to force air out of compressor. Back-seat service valve and
tighten cap. Compressor is now ready for operation.
REFRIGERANT OIL
Only new, pure, moisture-free refrigerant oil should be used
in the air conditioning system. This oil is highly refined and
dehydrated to a point where moisture content is less than 10 parts per
million. The oil container must be tightly closed at all times when
not in use, or moisture will be absorbed from the air and introduced
into the refrigeration system.
DISCHARGING SYSTEM
CAUTION: When discharging air conditioning system, use only approved
refrigerant recovery/recycling equipment. Make every attempt
to avoid discharging refrigerant into the atmosphere.
If compressor has stem-type service valves, it can be
isolated and removed without discharging entire system. Otherwise,
discharge system completely using approved refrigerant
recovery/recycling equipment before loosening any fittings.
DISCONNECTING LINES & FITTINGS
After system is discharged, carefully clean area around all
fittings to be opened. Always use 2 wrenches when tightening or
loosening fittings to avoid twisting or distorting lines. Cap or plug
all openings as soon as lines are removed. Do not remove caps until
immediately before connections are made. This will keep entry of air
and moisture to a minimum, reducing the chance of damage to
components.
Page 103 of 1378
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.
YORK - 2-CYLINDER COMPRESSOR OIL CHECKING
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, then install plug with new "O" ring. Purge compressor of
air.
Fig. 2: York A/C Compressor Oil Level Dipstick (Check oil w/ shaft
keyway facing head)
Courtesy of Chrysler Motors.
Page 161 of 1378
Discharge air warm when low
side gauge drops into vacuum.
Normal Normal Thermostatic switch system Defective Thermo-
only-compressor cycles off static Switch
and on too rapidly.
Normal Normal Cycling clutch systems Misadjusted Thermo-
only-Compressor doesn't static Switch or
turn on soon enough. or Defective
Discharge air becomes Pressure Sensing
warm as low side pressure Switch
rises.
Low Low Bubbles in sight glass. Low R-12 Charge
Outlet air slightly cool.
Low Low Sight glass clear or oil- Excessively Low
streaked. Outlet air very R-12 Charge
warm.
Low Low Outlet air slightly cool. Expansion Valve
Sweating or frost at Stuck Closed.
at expansion valve. Screen Plugged or
Sensing Bulb
Malfunction.
Low Low Outlet air slightly Restriction on High
cool. High side line Side
cool to touch. Sweating
or frost on high side.
Low High Evaporator outlet pipe STV Stuck Open
cold. Low side goes
into vacuum when blower
is disconnected.
High Low Evaporator outlet pipe STV Stuck Open
warm. Outlet air warm.
High Low Noise from compressor. Compressor
Malfunction
High High Outlet air warm. Liquid Condenser
line very hot. Bubbles Malfunction or R-12
in sight glass. Overcharge.
High High Outlet air slightly cool. Large Amount of Air
Bubbles in sight glass. and Moisture in
System.
High High Outlet air warm. Expansion Valve
Evaporator outlet Stuck Open
sweating and frost.
(1) - If equipped with a low refrigerant charge protection system,
compressor operation may have stopped.
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Page 164 of 1378
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
Page 169 of 1378
Fig. 3: Assembling Ford Spring-Coupling Fitting
3) Lubricate both sides of fitting with clean refrigeration
oil. Assemble the fitting by pushing together with a slight twisting
motion. Check to make sure spring is over flared end of female
fitting.
PLACING SYSTEM IN OPERATION
After component replacement and/or system servicing has been
completed and all connections have been made, proceed as follows:
1) Evacuate the system using vacuum pump.
2) Charge the system with R-12. See REFRIGERANT CAPACITY in
the A/C SYSTEM SERVICE SPECIFICATIONS in this article.
3) Leak test the system, with particular attention to all new
connections and components.
4) Make a performance test of the system. Never assume that a
recharging has automatically corrected a problem.
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 sections of this article. The charts in this
article 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.
Page 174 of 1378
![JEEP CHEROKEE 1988 Service User Guide Tiny bubbles in sight
glass. Discharge air warm
when low side gauge drops
into vacuum.
\](/img/16/57037/w960_57037-173.png "JEEP CHEROKEE 1988 Service User Guide Tiny bubbles in sight
glass. Discharge air warm
when low side gauge drops
into vacuum.
\")
Tiny bubbles in sight
glass. Discharge air warm
when low side gauge drops
into vacuum.
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Normal Normal Thermostatic switch system Defective Thermo-
only-compressor cycles off static Switch
and on too rapidly.
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Normal Normal Cycling clutch systems Misadjusted Thermo
to High only-Compressor doesn't static Switch or
turn on soon enough. Defective Pressure
Discharge air becomes Sensing Switch
warm as low side
pressure rises.
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Low Low Bubbles in sight glass. Low R-12 Charge
Outlet air slightly cool.
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Low Low Sight glass clear or oil- Excessively Low
streaked. Outlet air very R-12 Charge
warm.
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Low Low Outlet air slightly cool. Expansion Valve
Sweating or frost at Stuck Closed.
expansion valve. Screen Plugged or
Sensing Bulb
Malfunction
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Low Low Outlet air slightly cool. Restriction on
High side line cool to High Side.
touch. Sweating or frost
on high side.
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Low High Evaporator outlet pipe STV Stuck Open
cold. Low side goes into
vacuum when blower is
disconnected.
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High Low Evaporator outlet pipe STV Stuck Open
warm. Outlet air warm.
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High Low Noise from compressor Compressor
Malfunction
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High High Outlet air warm. Condenser
Liquid line very hot. Malfunction or
Bubbles in sight glass. R-12 Overcharge
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High High Outlet air slightly cool. Large Amount of
Bubbles in sight glass. Air and Moisture
in System.
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High High Outlet air warm. Expansion Valve
Evaporator outlet Stuck Open.
sweating and frost.
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(1) - If equipped with a low refrigerant charge protection system,
compressor operation may have stopped.
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A/C SYSTEM SERVICE SPECIFICATIONS
Page 187 of 1378
reading and reverse leads. If readings are the same, replace diode
trio.
2) A good diode trio will give a high and low reading. Repeat
tests between single connector and each of the 3 connectors. Connect
ohmmeter to each of the 3 connectors. If any readings are zero,
replace diode trio.
NOTE: Before replacing diode trio, also check rectifier bridge.
DO NOT use high voltage, such as 110
volt test light, when
testing diode trio.
Fig. 4: Bench Testing Diode Trio
Rectifier Bridge Test
1) Position ohmmeter with one lead touching grounded heat
sink and the other lead touching flat metal on one of the 3 terminals