JEEP CHEROKEE 1988 Service Repair Manual

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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.

PLACING SYSTEM IN OPERATION
After component service or replacement has been completed and
all connections have been made, evacuate system throughly with a
vacuum pump. Charge system with proper amount of refrigerant and
perform a leak test. Be sure to check all fittings that have been
opened. After system has been leak tested, make a system performance
check.
SANDEN SD508 5-CYLINDER OIL CHECKING
1) Discharge system using approved refrigerant
recovery/recycling equipment. Remove compressor belt and loosen
mounting bolts. Rotate compressor in brackets until filler plug is at
top. Clean area around filler plug and remove plug slowly. Rotate
front hub plate so notch in lobe is 110 degrees from the bottom. This
rotates ball end of top piston to align with oil fill port and allows
clearance for dipstick. See Fig. 1.
2) Insert compressor dipstick diagonally from right to left
until stop on dipstick contacts filler plug surface. Remove dipstick
and note oil fill level. Each mark on dipstick represents one ounce
of oil. Add oil if necessary to reach 3-4 ounce level.
Fig. 1: Sanden 5-Cylinder Oil Level Checking
YORK - 2-CYLINDER - PURGINE 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.
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.

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A/C -H EA TE R S YSTE M - M AN UAL

1988 J e ep C hero ke e
1988 Manual A/C-Heater Systems
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.
DESCRIPTION
On Cherokee, Comanche and Wagoneer, the Climate Control
System is an integral assembly combining air conditioning, heating and
ventilating capabilities for models with air conditioning. The A/C
registers are built into instrument panel.
On Wrangler models, a dual flow unit with the capability of
recirculating air or drawing air from outside is used. It incorporates
under-dash registers and uses a blend-air type system.
The A/C components include a compressor, condenser, receiver-
drier, a sight glass (in the receiver-to-evaporator line) and
evaporator housing. Evaporator housing contains evaporator core,
expansion valve, thermostat, wiring and drain tube. Blower motor and
fan are located in blower housing, which is attached to evaporator
housing.
Vents provided in evaporator housing are adjustable to direct
air to different positions in vehicle's interior. System controls
include fan and temperature control knobs built into lower evaporator
housing assembly or temperature and mode levers on control panel
integrated with instrument panel.
OPERATION
A/C SYSTEM CONTROLS
Temperature & Fan Control Knobs
(Wrangler)
The right rotary control knob allows selection of desired
temperature. Knob has "OFF" "1", "2" and "3" positions for different
levels of cooling. The left rotary fan switch (knob) controls blower
motor speed. Knob has "OFF", "LOW", "MED" and "HI" positions. Fan will
operate unless mode control lever is in "OFF" position.
The A/C fan switch is a 3-speed unit used in conjunction with
a blower motor resistor. Fan switch controls low, medium and high
speed operation. Switch may be serviced by removing access plate
located on lower evaporator core housing, below control panel.
The A/C temperature control switch has a thermostat unit
built-in. Cooling adjustment is done by turning knob in a clockwise
rotation. For fast, efficient system operation in hot weather, vehicle
should be purged of hot air by driving about 2-3 city blocks with at
least one window open. During this time, temperature control knob
should be rotated clockwise to "MAX" position and fan control knob
placed in "HI" position. This allows evaporator to pre-cool and avoid
typical first blast of warm air.
Temperature Control Panel
(Cherokee, Comanche & Wagoneer)
The upper temperature control (mode) lever includes "MAX",
"NORM", "BI-LEVEL", "VENT", "HEAT" and "OFF" positions. At the far end

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)

Discharge system (slowly to prevent loss of compressor oil)
using approved refrigerant recovery/recycling equipment. Disconnect
evaporator and condenser lines from receiver-drier. Detach mounting
screws from receiver-drier bracket. Remove receiver-drier.
Installation
To install, reverse removal procedure. Evacuate, leak test,
recharge. Check A/C system for proper operation.
Fig. 1: Exploded View of Wrangler Evaporator Housing
Courtesy of Chrysler Motors.
EVAPORATOR-BLOWER HOUSING &
HEATER & EVAPORATOR CORES
NOTE: The following procedures are for vehicles with A/C-heater
systems only. For replacement of heater cores on vehicles
with heater systems only, see HEATER SYSTEMS, JEEP article.
Removal (Cherokee, Comanche & Wagoneer)
1) Disconnect battery ground. Discharge A/C system using
approved refrigerant recovery/recycling equipment. Disconnect A/C
hoses from expansion valve. Drain cooling system. Disconnect heater
hoses at core tubes. Disconnect blower motor wires and vent tube.
2) Remove console (if equipped). Remove lower instrument
panel. Disconnect electrical connectors at A/C relay, blower motor
resistors and A/C thermostat. Disconnect vacuum hose at vacuum motor.
Cut plastic retaining strap holding evaporator-blower housing to
heater core housing.
3) Disconnect blend-air heater control cable. Detach clip at
rear of blower housing flange and remove retaining screws. Remove

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

panel to gain access to blower motor mounting screws.
2) Remove screws attaching evaporator housing to instrument
panel and mounting bracket. Lower evaporator housing and pull hoses
and grommet through opening.
Installation
To install, reverse removal procedure. Evacuate, leak test,
recharge and check A/C system for proper operation.
EXPANSION VALVE
Removal (Cherokee, Comanche & Wagoneer)
Discharge A/C system using approved refrigerant
recovery/recycling equipment. Disconnect A/C hoses from expansion
valve. Disconnect expansion valve from evaporator core inlet and
outlet tubes. Remove expansion valve.
Installation
To install, reverse removal procedure. Evacuate, leak test,
recharge and check A/C system operation.
NOTE: The expansion valve is pre-set and should not be adjusted. A
faulty valve requires replacement.
Removal (Wrangler)
1) Discharge system using approved refrigerant
recovery/recycling equipment. Remove evaporator housing. Remove
insulation wrapped around suction line and expansion valve.
2) Mark capillary tube location on suction line. Disconnect
inlet and outlet connections, capillary tube clamp and equalizer tube.
Remove expansion valve.
Installation
1) Clean suction line to provide positive contact with
replacement expansion valve capillary tube. Connect inlet and outlet
hoses. Clamp capillary tube securely at marked position and connect
equalizer tube.
2) Wrap expansion valve and line with insulation. Install
evaporator housing assembly. Evacuate, leak test, recharge and check
A/C system operation.
TEMPERATURE CONTROL THERMOSTAT
Removal (Cherokee, Comanche & Wagoneer)
1) Disconnect battery ground. Remove console (if equipped).
Remove lower instrument panel. Disconnect electrical connection at
thermostat. See Fig. 3.
2) Remove capillary tube retaining screw. Remove thermostat
retaining screws. Remove capillary tube from tube guide hole.
Installation
1) To install, feed capillary tube through tube guide hole
until Red tape on capillary tube just enters hole in housing. Install
capillary tube retaining screw and clip.
2) Install thermostat retaining screws and attach electrical
connection. To complete installation, reverse removal procedure.
CAUTION: Handle capillary tube with care to avoid bends or kinks
which could cause thermostat to malfunction.
Removal (Wrangler)
Remove evaporator housing assembly. Remove lower cover.

Carefully remove thermostat and capillary tube.
NOTE: On Wrangler models, servicing temperature control thermostat
requires disassembly of evaporator core housing.
Installation
To install, insert capillary tube into evaporator coil a
minimum of 2" (51 mm). See Fig. 4. Install thermostat and evaporator
housing lower cover.
Fig. 3: Capillary Tube & Temperature Control Thermostat Locations
Cherokee, Comanche and Wagoneer locations are shown.

Fig. 4: Wrangler Capillary Tube Position
Courtesy of Chrysler Motors.
TROUBLE SHOOTING