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A/C SYSTEM GENERAL SERVICING

1988 Jeep Cherokee

1988 AIR CONDITIONING & HEAT

A/C General Servicing

Diagnostic Procedures

Eagle & Jeep

* 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.

INTRODUCTION

This article is to be used for general service and diagnosis.

For specific repair or replacement procedures, use the appropriate

repair article in this section.

R-12 REFRIGERANT - SAFETY PRECAUTIONS

1) Always work in a well-ventilated, clean area. Refrigerant

(R-12) is heavier than oxygen, and will displace oxygen in a confined

area. Always wear eye protection when working around air conditioning

systems and R-12. The systems high pressure can cause severe injury

to eyes and skin if a hose were to burst. R-12 evaporates quickly

when exposed to atmosphere, freezing anything it contacts.

2) Use care when handling refrigerant containers. Do not

drop or strike containers. Do not expose refrigerant containers to

excessive heat. Containers must never be heated more than 125

Never expose R-12 directly to open flame.

CAUTION: When R-12 is exposed to an open flame, drawn into a running

engine, or detected with a Halide (propane) leak tester,

poisonous phosgene gas is formed. Keep work areas

ventilated and keep vehicles with running engines away.

USING INDIVIDUAL R-12 CANS

Disposable refrigerant cans (referred to as one pound cans)

have a flat type seal or a screw type seal, and the proper can tap

must be used for each type. Be sure sealing gasket on can tap is in

good condition. A proper safety can tap will prevent refrigerant from

flowing back into open can, as the tap has a one-way flow control.

NOTE: Recent findings by the EPA indicate that R-11, R-12 and

R-113 are harmful to the Earths protective Ozone layer.

Make every attempt possible, to avoid discharging R-11, R-12

or R-113 into the atmosphere.

USING MULTI-CAN DISPENSING VALVES

A multi-can dispensing valve allows the attachment of

several cans of refrigerant, and is a good substitute when a bulk

container is not available. Cans are installed onto each leg of the

multi-can dispensing valve in the same manner as the individual cans,

and each leg has its own can tap.

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. (16

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.

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

index notch is 110

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.

Fig. 1: 5-Cylinder Compressor Oil Check (Use dipstick J-29642-12)

YORK 2-CYLINDER COMPRESSOR SERVICING

from TDC of the cam rotor. Rotate the hub plate lobe until the�� from bottom center. See Fig. 1. Check this

JEEP WITH 2-CYLINDER 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

BEFORE OPENING THE SYSTEM

Before disconnecting any lines or fittings, the system must

be completely discharged using approved refrigerant recovery/recycling

equipment.

DISCONNECTING LINES & FITTINGS

1) After system is discharged, carefully clean entire area

around coupling nut to prevent dirt entering system. Always use two

wrenches to avoid twisting or distorting lines and fittings (hold

fitting with one wrench while loosening coupling nut with second

wrench).

2) Ford spring-coupling fittings require a special coupling

tool (Motorcraft YT-1056) to open or close. See procedure under

CONNECTING LINES & FITTINGS.

3) Cap or plug all LINES and FITTINGS immediately to prevent

entry of air and moisture into the system. Do not remove these caps

until connections are being made.

COMPONENT REPLACEMENT

When components are replaced, system oil level must be

adjusted. Add refrigeration oil to replacement component. See

Compressor Oil Check article, as well as, Component Oil Replacement

Quantities" chart under A/C SYSTEM SERVICE SPECIFICATIONS in this

article.

CONNECTING LINES & FITTINGS

All Except Ford Spring-Coupling Fitting

1) A new "O" ring should be used in all instances when

connecting lines and fittings (dip "O" ring in clean refrigeration oil

and make certain it is not twisted during installation). Always use

two wrenches to avoid twisting or distorting lines and fittings.

Tighten coupling nuts securely.

2) Ford spring-coupling fittings require a special coupling

tool (Motorcraft YT-1056) to open or close. Use the following

procedure to connect or disconnect the spring-coupling fitting.

Ford Spring-Coupling Fitting

1) Discharge system using approved refrigerant

recovery/recycling equipment. Place proper end of tool over

refrigerant line. Tool fits both 3/8" and 1/2" fittings. Push tool

into fitting cage to release spring inside. Pull lines apart and

remove tool.

2) Before connecting, check internal spring for damage. If

Necessary, pry spring out and replace it. Clean fittings and install

new "O" rings.

CAUTION: Use ONLY "O" rings designed for these Ford fittings

(Motorcraft YF-982). Normal refrigerant "O" rings will NOT

seal.

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.

ALTITUDE PRESSURE VARIATIONS

ALTITUDE PRESSURE VARIATIONS


Altitude (Ft. Absolute Pressure Gauge Altitude

Above Sea Level) of Atmosphere(psi) Correction(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) - Subtract correction shown from gauge readings.


ALTITUDE VACUUM VARIATIONS


Altitude (Ft. Complete Vacuum Gauge Altitude

Above Sea Level) (In. Hg) Correction (In. Hg)

0 ...................... 29.92 ....................... 0

1000 ................... 28.92 .................... +1.0

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.


OPERATIONAL TEST GAUGE READINGS

Normal System Operating Pressures (PSI) (1)


Low Side Gauge High Side Gauge

Application (Suction) (Discharge)

Thermostatic Switch .... 5-24 .................. 208-250

(1) - Pressure readings given are for a system in good

operating condition, at sea level and an ambient

temperature of 80

o F (27o C).


A/C SYSTEM PERFORMANCE CHECK TABLE

AIR CONDITIONING SYSTEM PERFORMANCE CHECK


PERFORM TESTS: SHOULD BE: IF:


Temperature Check Temperature Check Is

* 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

o F (1.7-7.2o C)


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 retouch

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.


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.


PRESSURE CHARTS

Fig. 4: Ambient Temperature/Pressure

Fig. 5: Evaporator Temperature/Pressure

A/C SYSTEM DIAGNOSIS WITH GAUGES

DIAGNOSIS WITH GAUGES - SYSTEMS WITH INSUFFICIENT OR NO COOLING


LOW SIDE HIGH SIDE OTHER SYMPTOMS(1) DIAGNOSIS

GAUGE GAUGE

Normal Normal No or few bubbles in sight Some Air and

glass. High side gauge may Moisture in System

go high. Low side gauge

does not fluctuate with

compressor on/off cycle.


Normal Normal Cools okay in morning but Excessive Moisture

not during hot part of day. in System

Tiny bubbles in sight

glass. Discharge air warm

when low side gauge drops

into vacuum.


Normal Normal Thermostatic switch system Defective Thermoonly-

compressor cycles off static Switch

and on too rapidly.


Normal Normal Cycling clutch systems Misadjusted Thermo

to High only-Compressor doesnt static Switch or

turn on soon enough. Defective Pressure

Discharge air becomes Sensing Switch

warm as low side

pressure 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.

expansion valve. Screen Plugged or

Sensing Bulb

Malfunction


Low Low Outlet air slightly cool. Restriction on

High side line cool to High Side.

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. Condenser

Liquid line very hot. Malfunction or

Bubbles in sight glass. R-12 Overcharge


High High Outlet air slightly cool. Large Amount of

Bubbles in sight glass. Air 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.


A/C SYSTEM SERVICE SPECIFICATIONS

REFRIGERANT OIL & R-12 CAPACITY TABLE


(1) Oil R-12

Application Ounces Ounces

Eagle ......................... 5.7 ........................... 36

(1) - Total system capacity, unless otherwise noted.


SYSTEM REFRIGERANT CAPACITIES


Application Pounds Ounces

Eagle

Medallion & Premier ..... 1 7/8 .............. 29

Summit (FX105V) ......... 2 1/4 .............. 36

Jeep

CJ Models ............... 2 1/2 .............. 40

Comanche .................. 2 ................ 32

All Other Jeep Models . 2 1/4 .............. 36


COMPONENT OIL REPLACEMENT QUANTITIES


Component Ounces

Accumulator ................................... (1)

Condenser ....................................... 1

Evaporator ...................................... 1

Receiver-Drier .................................. 1

Compressor

Premier ....................................... (1)

Medallion ..................................... 5.7

Grand Wagoneer .................................. 8

All Other Jeep Models ........................... 7

(1) - Add amount drained plus 1 ounce.


COMPRESSOR BELT TENSION (Lbs.) (1)


Application New Belt Used Belt

Eagle

1.4L & 1.7L ............ 120-160 ......... 90-115

Jeep

Regular Belt ........... 125-155 ......... 90-115

Serpentine Belt ........ 180-200 ........ 140-160

(1) - Using standard strand tension gauge.


COOLING SYSTEM CAPACITIES (1)


Application Quarts (Liters)

Eagle

Medallion & Premier

With A/C .............................. 4.8 (4.5)

Without A/C ........................... 4.4 (4.2)

Jeep

Cherokee & Wagoneer (2)

4-Cylinder ........................... 10.0 (9.5)

V6 .................................. 12.0 (11.4)

CJ & Scrambler

4-Cylinder ............................ 9.0 (8.5)

6-Cylinder ........................... 10.5 (9.9)

Grand Wagoneer & Truck (3)

6-Cylinder .......................... 12.5 (11.8)

V8 .................................. 15.5 (14.7)

(1) - May vary +/- 15% due to system variations.

(2) - Includes 2.3 qts. (2.2L) in recovery bottle.

(3) - Includes 1 qt. (.9L) for heater.