1988 JEEP CHEROKEE set clock

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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.

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.

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

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STA R TE R - B O SC H/M IT S U BIS H I

1 988 J e ep C hero ke e
1988 Starters
BOSCH & MITSUBISHI
Jeep with 4.0L 6-Cyl.
DESCRIPTION
NOTE: Information on Jeep 2.5L starter not available from
manufacturer.
Bosch and Mitsubishi use a permanent magnet starter. A
planetary gear train transmits power between starter motor and pinion
shaft. The starter magnetic field is produced by 6 permanent magnets.
The Mitsubishi starter is a 12-volt unit that has the solenoid mounted
on the starter housing. See Fig. 3.
TROUBLE SHOOTING
NOTE: See the TROUBLE SHOOTING - BASIC PROCEDURES article
in the GENERAL TROUBLE SHOOTING section.
TESTING (ON VEHICLE)
AMPERAGE DRAW TEST
NOTE: Engine should be at operating temperature before performing
this test. Heavy duty oil or a tight engine will increase
starter draw amperage. Tests are performed with standard
volt-ammeter tester.
1) Connect tester and remote starter switch. Set voltmeter
selector to 16-volt position. Select function to 0-500-amp scale.
Connect voltmeter leads to corresponding polarity battery terminals.
2) Connect ammeter leads to corresponding battery terminals.
Disconnect coil wire from distributor cap and attach to ground to
prevent engine from starting.
3) Crank engine and observe exact reading on voltmeter. Stop
cranking engine. Turn tester control knob clockwise until voltmeter
reads exactly the same as when engine was cranked with remote starter
switch. Ammeter should indicate starter draw of about 150-220 amps.
STARTER RESISTANCE TEST
Use a voltmeter that will indicate tenths of a volt. Without
disconnecting any starter connections, perform the following
resistance tests:
1) Perform following tests with engine cranking and all
terminals connected. Connect a voltmeter at following locations:
* Positive lead to battery positive post and negative lead
to battery terminal on starter.
* Positive lead to starter housing and negative lead to
negative post on battery.
* Positive lead to battery negative post and negative lead
to battery cable connector on engine block.
2) Each of these 3 connections should show a voltmeter

Install input shaft seal with spring in seal facing adjuster plug.
2) Install dust seal into adjuster plug. Rubber face of seal
must face away from plug. Install retainer ring. Install adjuster plug
"O" ring.
3) Assemble thrust bearing, thrust bearing race, and thrust
bearing spacer on adjuster plug. Using a brass or wooden dowel, press
bearing retainer into needle bearing bore.
RACK/PISTON & WORM
Disassembly
Remove worm, lower thrust bearing and bearing races from rack
piston. Remove piston ring and back-up "O" ring from rack/piston.
Remove ball return guide clamp, ball return guide and all ball
bearings from rack/piston.
Inspection
1) Clean and dry all parts. Inspect worm and rack/piston
grooves for scoring. Inspect ball bearings for damage. If any ball
bearings are damaged, replace entire set. Check ball guides for
pinching of ends.
2) Inspect lower thrust bearing races for cracking, scoring,
or pitting. Replace wormshaft and rack/piston as an assembly if either
part is damaged. Inspect rack/piston teeth for chips, cracks, dents or
scoring.
Reassembly
1) Install "O" ring and piston ring onto rack/piston using
care not to twist them. Install worm into rack/piston until worm is
against piston shoulder. Install ball bearings into rack/piston while
slowly rotating worm counterclockwise.
NOTE: See RACK PISTON & WORM ASSEMBLY BALL BEARINGS table for
number of balls to be installed. BE SURE to install light
and dark colored balls alternately, as Black balls are
.0005" smaller than Silver balls.
2) Install correct number of balls in ball guide. Bearings in
guide must be in sequence with bearings in rack/piston. Hold balls in
place with chassis lubricant and install return ball guide assembly
into position.
3) Install clamp and tighten attaching bolts. Alternate light
and dark colored balls when installing. See Fig. 10. Insert
rack/piston arbor into rack/piston until it contacts worm. Maintain
pressure on arbor, and back worm out of rack/piston. DO NOT allow ball
bearings to drop out of circuits.
RACK PISTON & WORM ASSEMBLY BALL BEARINGS TABLE









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Application Rack/Piston Guide
Jeep ...................... 18 ....................... 6









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