1994 JEEP CHEROKEE maint

WARNING: LARGE AMOUNTS OF REFRIGERANT
RELEASED IN A CLOSED WORK AREA WILL DIS-
PLACE THE OXYGEN AND CAUSE SUFFOCATION.
ALWAYS MAINTAIN GOOD VENTILATION SUR-
ROUNDING THE WORK AREA.
R-12 gas, under normal conditions, is non-poison-
ous.
WARNING: THE DISCHARGE OF R-12 GAS NEAR
AN OPEN FLAME CAN PRODUCE A VERY POISON-
OUS GAS CALLED PHOSGENE. PHOSGENE IS
GENERATED WHEN A FLAME-TYPE LEAK DETEC-
TOR IS USED.
CAUTION: When charging an A/C system always
keep the tank in an upright position. If the tank is
on its side or upside down, liquid refrigerant will
enter the system and may damage the compressor.
In most instances when charging or adding refrig-
erant, moderate heat is required to bring the pres-
sure of the refrigerant above the pressure of the
system. A bucket or large pan of hot water, not over
52ÉC (125ÉF), is all the heat required for this pur-
pose. DO NOT heat the refrigerant container with a
blow torch or any other means that would raise the
temperature and pressure above this temperature.
CAUTION: DO NOT allow liquid refrigerant to touch
bright metal. Refrigerant will tarnish bright metal
and chrome surfaces. Refrigerant in combination
with moisture is very corrosive and can cause ex-
tensive damage to all metal surfaces.
Avoid splashing the refrigerant on any surface.
RECYCLING
(R-12) refrigerant is a chloroflorocarbon (CFC) that
can contribute to the depletion of the ozone layer in
the upper atmosphere. Ozone filters out harmful ra-
diation from the sun. To assist in protecting the
ozone layer, Chrysler Corporation requires that an
(R-12) refrigerant recovery device that meets SAE
standard J1991 be used. Contact an automotive ser-
vice equipment supplier for refrigerant recycling
equipment that is available in your area. Refer to
the operating instructions provided with the recy-
cling equipment for proper operation.
SERVICE PRECAUTIONS
Never open or loosen a connection before discharg-
ing the system refrigerant.
A system which has been opened to replace a com-
ponent or one which has discharged through leakage
must be evacuated before charging.
Immediately after disconnecting a component from
the system, seal the open fittings with a cap or plug.Before disconnecting a component from the system,
clean the outside of the fittings thoroughly.
DO NOT remove the sealing caps from a replace-
ment component until ready to install.
Refrigerant oil will absorb moisture from the atmo-
sphere if left uncapped. DO NOT open an oil con-
tainer until ready to use and install the cap
immediately after using. Store the oil only in a clean
moisture-free container.
Before connecting an open fitting always install a
new seal ring. Coat the fitting and seal with clean
refrigerant oil before connecting.
When installing a refrigerant line avoid sharp
bends. Position the line away from the exhaust or
any sharp edges which may chafe the line.
Tighten fittings only to the specified torque. The
copper and aluminum fittings used in the A/C system
will not tolerate over tightening.
When disconnecting a fitting use a wrench on both
halves of the fitting to prevent twisting of the refrig-
erant lines or tubes.
DO NOT open a refrigerant system or uncap a re-
placement component unless it is as close as possible
to room temperature. This will prevent condensation
from forming inside of a component which is cooler
than the surrounding air.
Keep service tools and the work area clean. Con-
tamination of A/C system through careless work hab-
its must be avoided.
PRESSURE GAUGE AND MANIFOLD ASSEMBLY
Pressure Gauge and Manifold Assembly Tool
C-3740-B (Fig. 1) is the most important tool used to
service the air conditioning system. The gauge as-
sembly is used to determine:
²System high side gauge pressures
²System low side gauge pressures
²The correct refrigerant charge
²System diagnosis
It is designed to provide simultaneous high and low
side pressure indications, because these pressures
must be compared to determine the correct system
operation.
LOW SIDE GAUGE
The low side gauge is a compound gauge, which
means that it will register both pressure and vacuum
(Fig. 1). The compound gauge is calibrated 0-1034
kPa (0-150 psi) pressure and 0-760 mm (0-30 in.) of
mercury vacuum. It is connected to the suction ser-
vice valve to check the low side pressure or vacuum.
HIGH SIDE GAUGE
The high side gauge is used to check the pressure
in the discharge side of the air conditioning system
(Fig. 1).
24 - 2 HEATING AND AIR CONDITIONINGJ

(18) Disconnect the charging hoses from the ser-
vice valves.
COMPRESSOR OIL LEVEL
The compressor oil level must be checked and ad-
justed if the system has been discharged rapidly, or
when a component has been replaced. If a replace-
ment compressor is being installed, it must be filled
with new compressor oil (Suniso 5GS, or equivalent).
The normal quantity of oil required for the com-
pressor and entire system is 136 ml (4.6 fluid oz.) for
SD 709 compressor. DO NOT overfill the compressor.
Excessive amounts of oil in the system will hinder
compressor operation and reduce A/C performance.
CAUTION: The compressor is a high speed unit.
Satisfactory operation is dependent on sufficient lu-
brication; however, excess oil will hinder A/C per-
formance.
Two oil level checking procedures are necessary.
Use Procedure (A) when the compressor is being re-
placed and the system was discharged properly (no
oil loss). Use Procedure (B) for routine maintenance
or when checking oil level after replacing a system
component.
In cases where rapid loss of refrigerant and oil
occurred, the system must be evacuated and
purged. Then the compressor must be filled with
the necessary amount of oil to fill the entire sys-
tem.
PROCEDURE A
(1) Remove the oil filler plug, discharge cap and
suction port caps from the original and replacement
compressor.
(2) Use a clean container to drain the oil from the
replacement compressor. Drain the oil through the
oil filler plug hole, the discharge and suction. Then
rotate clutch front plate several times to push the oil
on cylinder out to discharge chamber of cylinder
head and drain the oil from discharge port.
(3) Drain the oil from the original compressor into
a measuring cup or graduated beaker in the same
way as Step 2. Note the amount of oil drained.
(4) Fill the replacement compressor with the same
amount of oil drained from the original compressor
plus 30 ml (1 fluid oz.).
FOR EXAMPLE:ÐIf the old compressor contained
103.5 ml (3.5 fluid oz.) of oil, fill the replacement
compressor with a total of 133 ml (4.5 fluid oz.) of oil.
PROCEDURE B
(1) Start the engine and operate the engine at idle.
(2) Operate the air conditioning system for 10 min-
utes to return the maximum amount of oil in the sys-
tem to the compressor.(3) Stop the engine and disconnect the magnetic
clutch feed wire.
(4) Front-seat the discharge and suction service
valves.
(5) Determine the mounting angle.
(a) Position an Angle Gauge across the flat sur-
faces of the front mounting ears.
(b) Center the bubble.
(c) Read the mounting angle to the closest de-
gree.
(d) These vehicles should have 0É mounting an-
gle.
(6) Remove the oil filler plug. Position internal
parts by rotation of front plate counterweight to 30É
angle (Fig. 5).
(7) Insert the dipstick tool to its STOP position.
The Dipstick Tool is part of Tool Kit 7851. The stop
is the angle near the top of the dipstick. The bottom
surface of the angle must be flush with the surface of
the oil filler hole.
(8) Remove dipstick. Count increments of oil.
(9) Use mounting angle table to determine correct
oil level for the compressor (Fig. 6).
(10) If the increments read on the dipstick do not
match the table, add or subtract oil to the mid-range
value.
FOR EXAMPLE:ÐIf the mounting angle is 10É
and the dipstick increment is 3, add oil in 30 ml (1
fluid oz.) increments until 5 is read on dipstick.
(11) Check that the sealing O-ring is not twisted.
(12) Seat and O-ring must be clean.
Fig. 5 Check Oil Level
24 - 6 HEATING AND AIR CONDITIONINGJ

²Used belt tensionÐ623-712 N (140-160 lb-f).
(5) Remove the tape or plastic plugs from all the
suction and discharge openings and install the ser-
vice valves on the compressor.
(6) Connect the clutch lead wire.
(7) Connect negative cable to battery.
(8) Evacuate, charge and test the system for leaks.
MAGNETIC CLUTCH
The magnetic clutch consists of a stationary elec-
tro-magnetic coil and a rotating pulley and plate as-
sembly.
The electromagnetic coil is retained on the com-
pressor with a snap ring and is dimpled to maintain
its position.The pulley and plate assembly are mounted on the
compressor shaft.
When the compressor is not in operation, the pul-
ley free wheels on the clutch hub bearing. When the
coil is energized the plate is magnetically engaged
with the pulley and turns the compressor shaft.
REMOVAL
(1) Insert the 2 pins of the front plate spanner into
any 2 threaded holes of the clutch front plate (Fig.
3). Hold clutch plate stationary. Remove hex nut
with 19 mm (3/4 inch) socket (Fig. 3).
(2) Remove clutch front plate using puller. Align
puller center bolt to compressor shaft (Fig. 4). Thumb
tighten the puller bolts into the threaded holes.
(3) Turn center bolt clockwise with 19 mm (3/4
inch) socket until front plate is loosened.
Fig. 1 Compressor and Mounting Bracket (LH Drive
Vehicles)
Fig. 2 Compressor and Mounting Bracket (RH Drive
Vehicles)
Fig. 3 Hex Nut Removal
Fig. 4 Clutch Front Plate Removal
24 - 18 HEATING AND AIR CONDITIONINGJ

CLIMATE CONTROL SYSTEMÐXJ VEHICLES
INDEX
page page
A/C Recirculating Air Door Vacuum Motor
Replacement.......................... 31
Blower Motor Resistors Replacement......... 35
Blower Motor/Fan Replacement.............. 26
CondenserÐ4.0L Engines.................. 32
Condenser/Receiver DrierÐ2.5L Engines....... 31
Defroster Duct Replacement................ 29
Description............................. 22
Evaporator Coil.......................... 34
Evaporator/Blower Housing................. 33Expansion (H) Valve...................... 35
Heater and A/C Control Panel Replacement.... 26
Heater Control Cable Replacement........... 30
Heater Core............................ 28
Heater Core Housing Replacement........... 29
Heater/Defroster/Instrument Panel Outlet Door
Vacuum Motor Replacement............... 30
Receiver DrierÐ4.0L Engines............... 32
Temperature Control Thermostat............. 35
DESCRIPTION
The Climate Control System combines air condi-
tioning, heating and ventilating capabilities for vehi-
cles equipped with air conditioning. Vehicles without
air conditioning perform heating and ventilating
functions without the air conditioning evaporator.
Both systems consist basically of 2 parts:
²Blower and Air Inlet Assembly
²Heater Core and Air Distribution Assembly
These assemblies, initially installed as a single
unit, may be removed separately from under the in-
strument panel as required for service.
HEATER SYSTEM
The heater system is a blend air type. Outside air
is heated and then blended in varying amounts with
cooler outside air to obtain the desired discharge
temperature. A heater coolant valve provides full
flow to the heater core for all heating modes. The
heater coolant valve remains closed for the ventila-
tion mode, allowing discharge air to approach the
outside ambient air temperature.
AIR CONDITIONING SYSTEM
The air conditioning system has an evaporator to
cool and dehumidify the incoming outside air prior to
blending with the heated air. The evaporator is in
operation during the A/C mode and also in the de-
frost mode for defogging purposes. The evaporator is
not in operation at ambient temperatures below ap-
proximately -1ÉC (30ÉF). To maintain minimum evap-
orator temperature, a fixed thermostat setting switch
cycles the compressor clutch. The blower is operatingthe heater or air conditioning systems, except the
OFF mode. In this mode (OFF) the blower and the
outside air are shut off.
The cooling unit is mounted on the dash panel and
the cooled air is discharged from the instrument
panel registers. The registers are adjusted to provide
general or localized cooling.
SIGHT GLASS
The sight glass is located on top of the receiver/
drier. The sight glass provides a visual check of the
system refrigerant level. A continuous stream of bub-
bles will appear in the sight glass when the system
charge is low. Bubbles will not appear when the sys-
tem is fully charged.
LOW PRESSURE SWITCH
The low pressure switch disengages the magnetic
clutch if the pressure in the system drops below 193
kPa (28 psi). This will occur with a loss in refriger-
ant or with cold ambient temperature.
HEATER VALVE
The heater valve regulates coolant flow to the
heater core. It requires vacuum to shut off flow to
the heater core.
These vehicles are equipped with a bypass-type
heater water valve. When the heater valve is closed,
coolant flow to the heater core is bypassed back to
the engine. When the heater valve is open, coolant is
directed through the heater core and back to the en-
gine.
24 - 22 HEATING AND AIR CONDITIONINGJ

FRESH AIR VENTILATION
The fresh air ventilating system (Fig. 3) is oper-
ated by the air control lever. When the lever is
moved to VENT position, outside air from the cowl
intake flows into the heater housing. Incoming air is
directed into the vehicle interior through vent doors
in the housing.
A door in the intake duct controls air flow into the
duct. The door is operated by a vacuum motor. The
motor is controlled by a vacuum switch in the heater
control panel. The vent air doors are opened and
closed by a cable and linkage operated by the air
control lever. Fresh air intake occurs only when the
lever is in the VENT position.
HEATER CONTROL PANEL REPLACEMENT
(1) Remove the instrument cluster bezel attaching
screws (Fig. 4).
(2) Remove the instrument cluster bezel.
(3) Remove the screws attaching the heater control
panel to the instrument panel.
(4) Slide the control panel outward and disconnect
the cables, vacuum hoses and electrical wires from
the control panel.
(5) Remove the control panel.
To install the control panel, reverse the removal
procedures.
BLOWER MOTOR/AIR DOOR MOTOR SWITCH
REPLACEMENT
(1) Remove the heater control panel (Fig. 5).
(2) Remove the air door motor switch.
(3) Remove the control knob from the blower
switch.
(4) Remove the screws that attach the switch to
the control panel.
(5) Remove the switch from the control panel.
To install the switches, reverse the removal proce-
dures.
VENT DOOR CONTROL CABLES
REMOVAL
(1) Disconnect the cable from the vent door.(2) Disconnect the cable from the heater control
panel lever. The cables are attached to the control
panel levers with plastic tabs. Press the tabs to-
gether and lift the cable upward to disengage it from
the lever.
(3) Remove the cable. The clip on the cable wire
has 2 functions. It attaches the cable to the vent door
and is also the self adjusting mechanism. Because
the left cable operates the right cable, the cables
must be installed as outlined to maintain the self ad-
justing feature and ensure proper vent door opera-
tion.
INSTALLATION
(1) To install the cables, connect the cables to the
heater control panel.
(2) Connect the right vent door cable. DO NOT
connect the left door cable at this time.
(3) Open and close the right vent door (one time)
using the air control lever on the heater control
panel.
(4) Connect the left vent door cable.
(5) Open and close both vent doors with the air
control lever. Verify that both vent doors open at the
same time.
Fig. 4 Instrument Cluster Bezel
Fig. 5 Control Switches
JHEATING AND AIR CONDITIONING 24 - 39

REFRIGERANT LEAK TESTING, DISCHARGING, EVACUATING AND CHARGING
LEAK TESTING REFRIGERANT
WARNING: REVIEW WARNINGS AND CAUTIONS IN
GENERAL INFORMATION SECTION OF THIS
GROUP BEFORE LEAK TESTING.
If A/C system is not cooling properly, determine if
system is fully charged. Refer to Refrigerant System
Diagnosis Chart. If the system is empty evacuate the
A/C system and charge system with 0.283 kPa (0.6
lbs. or 10 oz.) R-134a refrigerant. Refer to Charging
Refrigerant System for instructions. To detect a leak
in the system, perform the following procedures.
(1) Position the vehicle in a wind free work area.
This will aid in detecting small leaks.
(2) Bring A/C system up to operating temperature
and pressure. This is done by allowing the engine to
run with the A/C on for 5 to 7 minutes.
(3) Open hood 5 minutes prior to leak test. This
will dissipate any accumulated refrigerant in the en-
gine compartment.
(4) With the engine not running, use an R-134a
Electronic Leak Detector and search for leaks. Move
probe slowly along the bottom side of lines and fit-
tings, because R-134a is heavier than air. Fittings,
lines, or components that appear to be oily usually
indicates a refrigerant leak.
(5) To inspect the evaporator core for leaks. Set the
blower at low speed and the selector in PANEL and
RECIRC mode check for leaks at CENTER panel ou-
lets.
DISCHARGING REFRIGERANT SYSTEM
WARNING: REVIEW WARNINGS AND CAUTIONS IN
GENERAL INFORMATION SECTION OF THIS
GROUP BEFORE DISCHARGING SYSTEM.
R-134a refrigrant is a hydrofluorocarbon (HFC)
that does not contain chlorine. R-134a refrigerant Re-
covery/Recycling Station that meets SAE standard
J2210 must be used to discharge the refrigerant sys-
tem. Refer to the operating instructions provided
with the equipment for proper operation.
EVACUATING REFRIGERANT SYSTEM
WARNING: REVIEW WARNINGS AND CAUTIONS IN
GENERAL INFORMATION SECTION OF THIS
GROUP BEFORE EVACUATING SYSTEM.If the A/C system has been open to the atmosphere,
it must be evacuated before the system can be
charged. Moisture and air mixed with refrigerant will
raise the compressor head pressure above acceptable
operating levels. This will reduce the performance of
the air conditioner and damage the compressor. Mois-
ture will boil at near room temperature when ex-
posed to vacuum. To evacuate the refrigerant system
use following procedure:
(1) Connect a suitable charging station and mani-
fold gauge set to the vehicle.
(2) Open the low and high side valves and start
vacuum pump. When suction gauge reads 88 kPag
(26 in. Hg) vacuum or greater, close all valves and
turn off vacuum pump. If system fails to reach spec-
ified vacuum, the system has a leak that must be
corrected. If system maintains the specified vacuum
for 30 minutes, start the vacuum pump. Then open
the suction and discharge valves and evacuate an ad-
ditional 10 minutes.
(3) Close all valves. Turn off and disconnect the
vacuum pump.
The system is now ready to be charged with refrig-
erant.
CHARGING REFRIGERANT SYSTEM
WARNING: REVIEW WARNINGS AND CAUTIONS IN
GENERAL INFORMATION SECTION OF THIS
GROUP BEFORE CHARGING SYSTEM.
After the system has been tested for leaks and
evacuated, a refrigerant charge can be injected into
the system. Refer to refrigerant capacities for proper
amount of refrigerant charge.
The most accurate method of charging is to com-
pletely evacuate the system. Then charge the system
using a Recovery/Recycling Station approved for
R-134a refrigerant. Refer to the operating instruc-
tions provided with the equipment for proper opera-
tion.
CAUTION: Do not over charge refrigerant system.
This will cause excessive compressor head pres-
sure and can cause noise and system failure.
REFRIGERANT CHARGE CAPACITY
The R-134a system charge capacity is 0.9 kPag (32
oz.) for XJ and YJ vehicles.
8 AIR CONDITIONINGJ

EMISSION CONTROL SYSTEMS
CONTENTS
page page
COMPONENT REMOVAL/INSTALLATION...... 8
EVAPORATIVE EMISSION CONTROLS....... 4EXHAUST EMISSION CONTROLS........... 7
GENERAL INFORMATION.................. 1
GENERAL INFORMATION
INDEX
page page
DRB Scan Tool........................... 2
Service Reminder Indicator (SRI) Lamp......... 1Vacuum Hose Routing Schematics............ 1
Vehicle Emission Control Information (VECI) Label . 1
SERVICE REMINDER INDICATOR (SRI) LAMP
The instrument panel mounted SRI lamp was for-
merly referred to as the emission maintenance re-
minder (EMR) lamp. It isnot usedon any Jeep
model for the 1994 model year.
VEHICLE EMISSION CONTROL INFORMATION
(VECI) LABEL
All vehicles are equipped with a combined VECI
label. The label is located in the engine compartment
(Figs. 1 or 2). The label contains the following:
²Engine family and displacement
²Evaporative family
²Emission control system schematic
²Certification application
²Engine timing specifications (if adjustable)
²Idle speeds (if adjustable)
²Spark plug and plug gap
The label also contains an engine vacuum sche-
matic. There are unique labels for vehicles built for
sale in the state of California and the country of
Canada. Canadian labels are written in both the En-
glish and French languages. These labels are perma-
nently attached and cannot be removed without
defacing information and destroying it.
The VECI label illustration (Fig. 3) is used as
an example only.Refer to the VECI label located in
the engine compartment (Figs. 1 or 2) for actual
emission information.
VACUUM HOSE ROUTING SCHEMATICS
The vacuum hose routing schematics are used
as examples only.If there are any differences be-
tween these schematics and the Vehicle Emission
Fig. 1 VECI Label LocationÐXJ Models
Fig. 2 VECI Label LocationÐYJ Models
JEMISSION CONTROL SYSTEMS 25 - 1

EVAPORATIVE EMISSION CONTROLS
INDEX
page page
Crankcase Ventilation System................ 5
EVAP (Evaporation) Control System........... 4
EVAP Canister........................... 4Fuel Tank Filler Tube Cap.................. 4
Pressure Relief/Rollover Valve................ 5
EVAP (EVAPORATION) CONTROL SYSTEM
GENERAL INFORMATION
The function of the EVAP control system is to pre-
vent the emissions of gasoline vapors from the fuel
tank into the atmosphere. When fuel evaporates in
the fuel tank, the vapors pass through vent hoses or
tubes to a carbon filled EVAP canister. They are
temporarily held in the canister until they can be
drawn into the intake manifold when the engine is
running.
The EVAP canister is a feature on all models for
the storage of fuel vapors from the fuel tank.
The hoses used in this system are specially
manufactured. If replacement becomes neces-
sary, it is important to use only fuel resistant
hose.
EVAP CANISTER
A sealed, maintenance free, EVAP canister is used
on all vehicles. On XJ models, the EVAP canister is
located in the engine compartment on the passenger
side frame rail (Fig. 4). On YJ models, the EVAP
canister is located in the engine compartment on the
dash panel and below the brake master cylinder (Fig.
5). The EVAP canister is filled with granules of an
activated carbon mixture. Fuel vapors entering the
EVAP canister are absorbed by the charcoal gran-
ules.
CANISTER OPERATION
The EVAP canister is equipped with a vacuum con-
trolled purge shutoff switch (orifice) (Figs. 4 or 5)
that controls canister purge operation. The switch is
open when manifold vacuum is applied to it. When
the engine is operating, the EVAP canister purge
function draws fresh air through the top of the can-
ister. This causes the stored vapors to be drawn out
of the canister and into the airstream in the air
cleaner snorkel (Fig. 6).
The air cleaner contains a venturi in the air
cleaner cover used as a purge line vacuum source
(Fig. 6). The venturi effect increases the speed of the
intake air flowing by the slots in the venturi wall.
This creates a low pressure area around the slots.
When the purge shutoff switch is open, vapors from
the canister are drawn through slots and into the
airstream flowing through the venturi (Fig. 7). The
vapors pass through the intake manifold into the en-
gine combustion chambers where they are consumed
during engine combustion.
FUEL TANK FILLER TUBE CAP
The fuel tank filler tube cap incorporates a two-
way relief valve that is closed to atmosphere during
normal operating conditions. The relief valve used in
fuel filler caps of all models is calibrated at a pres-
sure of 10 kPa (1.5 psi) or a vacuum of 6 kPa (1.8 in.
Hg). When the pressure or vacuum is relieved, the
valve returns to the normally closed position.
Fig. 4 EVAP Canister LocationÐXJ Models
Fig. 5 EVAP Canister LocationÐYJ Models
25 - 4 EMISSION CONTROL SYSTEMSJ