1988 JEEP CHEROKEE oil pressure

of the scale, a symbol for defroster indicates defrost position. In
"BI-LEVEL" position, a mixture of floor heat and defroster air is
obtained.
The lower temperature control lever operates blend-air door
in heater core housing. At full right position, all air is directed
through heater core, providing maximum heat flow. At full left
position, all air is directed around heater core providing fresh air.
Control can be set in any intermediate position to provide a blend of
heated and unheated air. Heater must be in heat or defrost mode before
any air can enter vehicle.
TROUBLE SHOOTING
See JEEP TROUBLE SHOOTING at the end of this article.
REMOVAL & INSTALLATION
CONDENSER
Removal (Cherokee, Comanche & Wagoneer) NOTE: On these
models, condenser and receiver-drier are replaced
as a unit.
1) Drain radiator. Disconnect fan shroud and radiator hoses.
Disconnect automatic transmission cooler lines (if equipped).
Discharge A/C system using approved refrigerant recovery/recycling
equipment.
2) Disconnect A/C hoses from condenser. Unplug low pressure
switch. Remove radiator and condenser as an assembly. Detach condenser
retaining bolts. Separate condenser from radiator. Remove receiver-
drier from condenser.
NOTE: Plug receiver-drier openings whenever unit is removed from
condenser. Add 1 oz. of refrigerant oil (AMC No. 8132400) to
system when replacing condenser.
Installation
To install, reverse removal procedure. Fill radiator.
Evacuate, leak test, recharge and check A/C system operation.
Removal (Wrangler)
1) Discharge system (slowly to prevent loss of compressor
oil) using approved refrigerant recovery/recycling equipment. Drain
coolant. Remove fan shroud and radiator. Disconnect pressure line at
condenser. Remove condenser mounting screws. Tilt bottom of condenser
toward engine.
2) From underside of vehicle, disconnect hose attaching
receiver-drier to evaporator. Plug all openings to prevent entry of
dirt or moisture. Remove receiver-drier and condenser assembly. Remove
receiver-drier from condenser.
Installation
To install, reverse removal procedure. Fill radiator.
Evacuate, leak test, recharge and check A/C system operation.
RECEIVER-DRIER
NOTE: On Cherokee, Comanche and Wagoneer, receiver-drier is
removed with condenser and radiator as an assembly.
Removal (Wrangler)









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Compressor Runs Rough
* Incorrect oil or refrigerant level.
* Internal compressor damage.
Compressor Intermittent or Inoperative
* Drive belt slipping.
* Faulty clutch air gap.
* Clutch coil wiring broken or frayed.
Noisy Compressor
* Mounting bolts loose.
* Clutch slipping.
* Improper charge in system.
* Bad clutch or pulley bearings.
* Incorrect oil level.
* Valve plate damaged.
* Piston slap.
Excessive Vibration
* Incorrect belt tension.
* Clutch loose.
* Pulley misaligned.
* System overcharged.
A/C Air Flow Stops on Acceleration
* Defective vacuum storage tank.
* Vacuum line separated or defective.
* Vacuum switch defective.
* Vacuum leak.
High Suction Pressure with Very Low Discharge Pressure
* Valve plate or gasket broken or deformed.
Very Low Suction and Discharge Pressure
* Low refrigerant charge.
* Compressor leak.
* System leak.
Heater Control Valve Does Not Close with Vacuum Applied
* Faulty heater control valve.
No Vacuum at Heater Control Valve with Lever at Extreme Left
* Vacuum source hose disconnected.
* Leaking vacuum hose.
* Faulty check valve.
* Control panel switch defective or misadjusted.
Frozen Evaporator Core
* Faulty thermostat.
* Thermostat capillary tube improperly installed.
* Thermostat not adjusted properly.
Condensation Dripping in Passenger Compartment
* Drain hose plugged or improperly installed.
* Insulation missing or improperly installed.









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TESTING
Note: The following test applies to all Jeep models except Cherokee
and Wagoneer.

HEATER HOSES
HIGH PRESSURE RELIEF VALVES (HPRV)
IDLERS
IN-LINE FILTERS
METAL FITTINGS
METAL LINES
MIX AND AIR CONTROL DOORS (BLEND DOORS)
O-RINGS
ORIFICE TUBES
PILOT-OPERATED ABSOLUTES (POAS)
PLENUMS
PRESSURE CONTROL VALVES
PRESSURE SENSORS
PULLEYS
RADIATORS
RECEIVER-DRIERS
REFRIGERANT
REFRIGERANT OIL
RELAYS
SEALS
SERVICE PORTS
SPRING LOCK COUPLINGS
SUCTION THROTTLING VALVES (STVS)
SWITCHES (ELECTRICAL)
TENSIONERS
THERMISTORS AND PRESSURE SENSORS
THERMOSTATS AND HOUSINGS
VACUUM HOSES AND TUBES
VACUUM RESERVOIRS
VACUUM TUBES
VALVES IN RECEIVER (VIRS)
WATER PUMPS (ELECTRIC AUXILIARY)
WIRING HARNESSES AND CONNECTORS
MOTORIST ASSURANCE PROGRAM (MAP)
OVERVIEW
The Motorist Assurance Program is the consumer outreach
effort of the Automotive Maintenance and Repair Association, Inc.
(AMRA). Participation in the Motorist Assurance Program is drawn from
retailers, suppliers, independent repair facilities, vehicle
manufacturers and industry associations.
Our organization's mission is to strengthen the relationship
between the consumer and the auto repair industry. We produce
materials that give motorists the information and encouragement to
take greater responsibility for their vehicles-through proper,
manufacturer-recommended, maintenance. We encourage participating
service and repair shops (including franchisees and dealers) to adopt
(1) a Pledge of Assurance to their Customers and (2) the Motorist
Assurance Program Standards of Service. All participating service
providers have agreed to subscribe to this Pledge and to adhere to the
promulgated Standards of Service demonstrating to their customers that
they are serious about customer satisfaction.
These Standards of Service require that an inspection of the
vehicle's (problem) system be made and the results communicated to the\
customer according to industry standards. Given that the industry did
not have such standards, the Motorist Assurance Program successfully
promulgated industry inspection communication standards in 1994-95 for
the following systems: Exhaust, Brakes, ABS, Steering and Suspension,
Engine Maintenance and Performance, HVAC, and Electrical Systems.
Further, revisions to all of these inspection communication standards

missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Contaminated, affecting
performance ............ A ............ Require 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.
Fusible plug leaking .... A .... Require replacement of plug.
Leaking ................. A ............ Require 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.









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REFRIGERANT
NOTE: Refrigerants include any SNAP (Significant New Alternative
Policy)-approved blends.
REFRIGERANT INSPECTION









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Condition Code Procedure
Contaminated (other than
refrigerant blends) .... B ........ Require service to remove
contamination.
Different types of
refrigerants in the same
system (other than
refrigerant blends) .... B ................. Require repair.
Overcharged ............. B ................. Require repair.
Refrigerant type
does not match
fittings and label ..... B ................. Require repair.
Undercharged ............ B ................. Require repair.









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REFRIGERANT OIL
REFRIGERANT OIL INSPECTION








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Condition Code Procedure
Contaminated ............ 1 .. Require repair or replacement.
Overfilled .............. B ................. Require repair.

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.\
)
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.

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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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.

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.