check engine JEEP CHEROKEE 1988 Service Owner's Manual
[x] Cancel search | Manufacturer: JEEP, Model Year: 1988, Model line: CHEROKEE, Model: JEEP CHEROKEE 1988Pages: 1378, PDF Size: 19.9 MB
Page 107 of 1378
housing attaching nuts from studs on engine compartment side of dash
panel. Remove evaporator drain tube.
4) Remove right kick panel. Detach instrument panel support
bolt. Gently pull on right side of dash, then rotate housing downward
and toward rear of vehicle to disengage housing studs from dash panel.
Remove evaporator-blower housing.
5) To remove heater core, detach retaining screws. Remove
heater core by pulling straight out of housing. To remove evaporator
core, detach top housing retaining screws, then remove top of
evaporator housing.
6) Remove thermostatic switch and capillary tube. Detach 2
evaporator retaining screws and lift evaporator core from housing.
Remove expansion valve from evaporator.
Installation
1) To install components, reverse removal procedure. When
installing evaporator core, install thermostatic switch and capillary
tube before installing top of housing.
2) When installing heater core, ensure seal is properly
cemented in place to prevent it from moving when blower assembly is
installed. Evacuate, leak test, recharge and check A/C system
operation.
NOTE: The evaporator housing mounting location is similar to
Wrangler, except blower motor is mounted horizontally to
firewall.
Removal (Wrangler)
1) Discharge system using approved refrigerant
recovery/recycling equipment. Disconnect inlet line at compressor.
Disconnect hose, at quick-disconnect coupling, between receiver-drier
and evaporator. Remove hose clamps and dash grommet retaining screws.
See Fig. 2 .
Fig. 2: Wrangler Evaporator Housing Mounting Screw Locations
Courtesy of Chrysler Motors.
NOTE: It is not necessary to discharge system to service blower
motor. Evaporator housing may be lowered from instrument
Page 115 of 1378
System Charge Test
1) To check system refrigerant level, a sight glass has been
incorporated into the receiver-to-evaporator hose at the receiver end.
A continuous stream of bubbles will appear in the sight glass of a
system that is not properly charged. However, both properly charged
systems and discharged systems will appear the same because of a lack
of bubbles.
2) To test for discharge condition, cycle the clutch off and
on with engine at 1500 RPM. When clutch is off, bubbles will appear if
there is refrigerant in the system. If no bubbles appear, system is
discharged. If discharged, leak test, repair and recharge system.
A/C SYSTEM OPERATION CHART & VACUUM DIAGRAM
A/C SYSTEM OPERATION TABLE \
\
\
\
\
\
\
MODE
LEVER BLOWER PANEL FLOOR DEFROST WATER
POSITION AIR DISCHARGE SPEEDS DOOR DOOR DOOR VALVE
\
\f\
\f\
\f\
\f\
\f\
\f\
Off(
1)( 2) Closed None Open ( 3) Closed Closed
\
\f\
\f\
\f\
\f\
\f\
\f\
Max A/C Panel Regis- 4
(
1)( 4) ters With Open Bleed Closed Open( 5)
Floor Bleed
\
\f\
\f\
\f\
\f\
\f\
\f\
Norm A/C Panel Regis- 4(
6) Open Bleed Closed Open( 5)
(
7)( 4) ters With
Floor Bleed
\
\f\
\f\
\f\
\f\
\f\
\f\
Bi-Level Panel 4(
6) Open Open Bleed Open( 1)
(
7)( 4) Registers
and Floor
With Def.
Bleed
\
\f\
\f\
\f\
\f\
\f\
\f\
Vent Panel 4 Open Bleed Closed Closed
(
7)( 2) Registers
With Floor
Bleed
\
\f\
\f\
\f\
\f\
\f\
\f\
Heat Floor With 4 Closed Open Bleed Open(
1)
(
7)( 2) Def. Bleed
\
\f\
\f\
\f\
\f\
\f\
\f\
Def. Defroster 4 Closed Bleed Open Open(
1)
(
7)( 2) With Floor
Bleed
\
\
\
\
\
\
\
(
1) - Recirculating Door is in Recirc. position.
(
2) - Indeterminate
(
3) - A/C Compressor is OFF
(
4) - A/C Compressor is ON
(
5) - Water valve closes in full "COOL" temperature lever position.
(
6) - Speeds are reduced by approximately 2.0 Volts.
(
7) - Recirculating Door is in Outside position.
\
\
\
\
\
\
\
\b
Page 136 of 1378
Threads damaged ......... A .. Require repair or replacement.
Threads stripped (threads
missing) ............... A ............ Require 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) - Refer to manufacturer's diagnostic trouble code
procedure and require repair or replacement of
affected component(s).
( 2) - Determine cause and correct prior to repair or
replacement of part.
( 3) - Determine source of contamination, such as engine coolant,
fuel, metal particles, or water. Require repair or
replacement. Check for accepted cleaning procedure.
( 4) - Inoperative includes intermittent operation or out of
OEM specification. Some components may be serviceable.
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COOLANT
COOLANT INSPECTION \
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Condition Code Procedure
Acidity (pH) incorrect .. 1 ........... Suggest correction or
replacement.
Contaminated ............ B ...... ( 1) Require replacement or
recycling. Further
inspection required.
Level incorrect ......... B .......... ( 2) Require filling to
proper level.
Maintenance intervals ... 3 ........ ( 3) Suggest replacement.
Mixture incorrect ....... B ........... Require correction or
replacement.
Type incorrect .......... B ............ Require replacement.
( 1) - Determine source of contamination and require correction
prior to coolant replacement.
( 2) - Determine source of incorrect level and suggest repair.
( 3) - The system should be drained and/or flushed and
refilled with correct coolant according to OEM
recommended service interval and procedures.
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COOLING FAN BLADES
COOLING FAN BLADE 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.
Page 157 of 1378
\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 \
\
\
\
\
\
\
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
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 165 of 1378
Information pertaining to Sanden compressors in this article,
will be found in earlier articles under Sankyo compressors.
AMERICAN MOTORS & JEEP WITH 5-CYLINDER COMPRESSOR
Compressor Overhaul
1) After the compressor and system have been run, stop the
engine. Slowly discharge system using approved refrigerant
recovery/recycling equipment. Clean and cool dipstick with R-12.
2) Loosen the compressor mounting bolts, remove the drive
belt, and move the compressor to a bench for easiest and most accurate
measurement. Position the compressor so that the oil fill plug is at
top dead center.
3) Thoroughly clean the oil fill plug and the area around it.
Loosen the fill plug slowly to allow trapped refrigerant pressure to
escape through the loosened threads.
4) The front plate hub has a lobe, which is indexed (notched)\
180
from TDC of the cam rotor. Rotate the hub plate lobe until the
index notch is 110 from bottom center. See Fig. 1. Check this
position by looking through the oil fill hole and noting that the ball
end of the top piston rod lines up with the fill hole.
5) Looking at the front end of the compressor, insert the
dipstick diagonally from upper left to lower left until the dipstick
stop contacts the filler hole surface. Remove dipstick and note oil
level. Oil level should be between the 4th and 6th increment on the
dipstick (3-4 ounces). Add oil as necessary.
Compressor Replacement
If system was opened by a leak or so quickly that oil was
lost, install new compressor with all the oil it contains. If system
was opened slowly and oil was not lost, drain oil from new compressor
and measure. Reinstall 6 ounces of oil back into new compressor prior
to installation.
Component Replacement
If a hose, receiver-drier, condenser, expansion valve or
evaporator core requires replacement, add 1 ounce of new oil for each
new component installed.
Compressor Oil Check
1) Discharge system, using approved refrigerant
recovery/recycling equipment, or isolate compressor. Remove oil filler
plug. Look through oil filler plug hole and rotate clutch front plate
to position piston connecting rod in center of oil filler plug hole.
2) Insert dipstick (J-29642-12) through oil filler plug hole\
to the right of piston connecting rod until dipstick stop contacts the
compressor housing.
3) Remove dipstick and count number of increments covered
with oil. If compressor is properly filled, oil will cover 4-6
increments on the dipstick. Adjust oil level as necessary.
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 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 180 of 1378
AIR IN JE C TIO N S YSTE M
1988 J e ep C hero ke e
1988 Exhaust Emission Systems
JEEP PULSE AIR INJECTION SYSTEM
4.2L
DESCRIPTION
Pulse air injection system is used to inject fresh air into
exhaust system. When fresh air is injected into hot exhaust gases,
combustion takes place. This reduces amount of unburned fuel that
escapes into the atmosphere.
System consists of check valves, control valves, control
valve solenoids, vacuum reservoir, vacuum lines and air lines. Pulse
air system is capable of injecting air at both catalytic converter
(downstream) or at front exhaust pipe.
OPERATION
Pulse air system uses alternating positive and negative
pressure pulsations in exhaust system to draw in fresh air through
air cleaner. Check valves are used to allow fresh air into exhaust,
but prevent exhaust from flowing back into intake system.
Air is switched between upstream and downstream injection by
2 vacuum-operated control valves. Each control valve is switched by
an electrically operated-vacuum solenoid.
Vacuum solenoids are switched on and off by MCU according to
engine operating conditions. Vacuum storage tank maintains vacuum
supply to switching solenoids.
DIAGNOSIS & TESTING
1) Check condition of all hoses and lines in system. Reroute
any kinked or restricted hoses. Repair or replace any cracked or
broken hoses. To check system operation, feel for suction in
injection hoses at air cleaner.
2) If problem exists, check to see if vacuum is being
supplied to the valve. If vacuum is not present at valve(s), check
vacuum lines or ports.