1994 JEEP CHEROKEE engine

CLIMATE CONTROL SYSTEMÐYJ VEHICLES
INDEX
page page
A/C Blower Motor........................ 43
A/C Condenser.......................... 42
A/C Control Panel........................ 41
Blower Motor (Heating).................... 40
Blower Motor/Air Door Motor Switch Replacement . 39
Defroster Nozzle and Duct................. 40
Description (Air Conditioning)................ 41
Description (Heating)...................... 37
Evaporator and Housing................... 42
Expansion (H) Valve...................... 43Fresh Air Door Vacuum Motor............... 41
Fresh Air Intake Duct..................... 41
Fresh Air Ventilation...................... 39
Heater Control Panel Replacement........... 39
Heater Core and Housing.................. 40
Heater/Defroster Operation................. 37
Receiver-Drier Replacement................ 42
Sight Glass............................. 41
Vent Door Control Cables.................. 39
DESCRIPTION (HEATING)
A blend-air heating system is used in YJ vehicles.
The blend-air system provides a constant flow of en-
gine coolant through the heater core.
The temperature of heated air entering the passen-
ger compartment is controlled by regulating the
quantity of air flow through the heater core. This is
accomplished by blending a controlled amount of un-
heated air from outside the vehicle with heated air
from the heater core.
HEATER/DEFROSTER OPERATION
The heater core is connected to the engine cooling
system. It operates on the circulation of heated en-
gine coolant through the core and a supply of fresh
air drawn in through the intake grille on the cowl.
Engine coolant flows through the heater core at all
times.
The heater controls are on the heater control panel
(Fig. 1).
The air control lever (Fig. 1) operates a door in the
fresh air intake duct. The door controls the amount
of fresh air flow into the heater housing and core.
When the lever is in the OFF position, the intake
door is closed preventing air flow into the housing.The temperature control lever (Fig. 1) determines
air flow through the heater core. The lever operates
the heater housing blend-air door which controls air
flow through the core.
The blower motor is operated by the control switch
(Fig. 1). The switch provides 3 blower speeds for in-
creased air flow in heat or defrost mode.
HEATING
Maximum air flow and heater output occurs when
the air control lever is in HEAT position and the
temperature control lever is in WARM position. The
blend-air door is closed and all intake air is directed
through the heater core in this operating mode (Fig.
2).
Temperature regulation of the heated air is deter-
mined by position of the temperature control lever.
Moving the control lever from WARM to an in-be-
tween position, opens the blend-air door in the heater
housing. As the door opens, unheated outside air is
drawn into the system and blended with heated air
from the core.
DEFROSTING
The heater housing contains a defroster door to di-
vert heated air to the defroster duct and windshield
outlets (Fig. 2). Defrost air flow is controlled by the
air control lever.
For defroster operation, the air control lever must
be moved to the defrost detent. The detent is identi-
fied by the defrost symbol on the control panel. In
this position, the defroster door in the heater housing
diverts all heated air (from the core) to the defroster
duct windshield outlets.
If the air control lever is moved to any position be-
tween the heat and defrost detents, the defroster door
does not close completely. In this mode, the door re-
mains partially open causing heated air to be divided
equally between the heat and defrost outlets.
Fig. 1 Heater Control Panel
JHEATING AND AIR CONDITIONING 24 - 37

HEATER CORE AND HOUSING
REMOVAL
WARNING: HOT ENGINE COOLANT CAN CAUSE
SEVERE BURNS. DO NOT OPEN THE RADIATOR
DRAIN COCK WHEN THE COOLING SYSTEM IS
HOT AND PRESSURIZED. ALLOW THE COOLANT
TO DECREASE TO ROOM TEMPERATURE BEFORE
STARTING REPAIR OPERATIONS.
(1) Drain approximately 1.9 liters (2 qts) of coolant
from the radiator. Drain the coolant into a clean con-
tainer.
(2) Disconnect the heater hoses.
(3) Disconnect the vent door cables.
(4) Disconnect the blower motor wire.
(5) Disconnect the defroster duct.
(6) Remove the nuts that attach the heater hous-
ing studs to the engine compartment side of the dash
panel.
(7) Remove the heater housing assembly by tilting
it downward, to disengage it from the defroster duct.
Pull it rearward and out from under the instrument
panel.
(8) Remove the heater hosing cover from the hous-
ing.
(9) Remove the heater core from the housing.
INSTALLATION
(1) Install the heater core in the housing and in-
stall the cover on the housing.
(2) Position the heater housing on the dash panel.
Be sure the housing studs all extend through the
dash panel.
(3) Install the seals on the heater core outlet and
inlet tubes and over the blower motor housing.
(4) Install the attaching nuts on the housing studs.
CAUTION: DO NOT over tighten the attaching nuts.
The housing could become distorted causing air
leaks and improper heater door operation. Tighten
the nuts alternately and evenly until 2 stud threads
are visible beyond each nut.
(5) Connect the defroster duct to the housing.
(6) Connect the blower motor wire.
(7) Connect the vent door control cables.
(8) Connect the heater hoses.
(9) Fill and bleed the cooling system.
(10) Check system operation.
BLOWER MOTOR (HEATING)
REMOVAL
(1) Remove the heater housing.
(2) Remove the blower motor-to-heater housing at-
taching screws/nuts.
(3) Remove the blower motor from the housing.
INSTALLATION
(1) Position the blower motor into the housing.
(2) Install and tighten the blower motor-to-heater
housing attaching screws/nuts.
(3) Install the heater housing.
(4) Check blower motor and heater operation.
DEFROSTER NOZZLE AND DUCT
REMOVAL
WARNING: HOT ENGINE COOLANT CAN CAUSE
SEVERE BURNS. DO NOT OPEN THE RADIATOR
DRAIN COCK WHEN THE COOLING SYSTEM IS
HOT AND PRESSURIZED. ALLOW THE COOLANT
TO DECREASE TO ROOM TEMPERATURE BEFORE
STARTING REPAIR OPERATIONS.
(1) Drain approximately 1.9 liters (2 qts) of coolant
from the radiator. Drain the coolant into a clean con-
tainer.
(2) Disconnect the heater hoses.
(3) Remove the nuts attaching the heater housing
studs to the engine compartment side of the dash
panel.
(4) Disconnect the speedometer cable.
(5) Remove the glove box.
(6) Tilt the heater housing back and pull it rear-
ward and out from under the instrument panel.
(7) Disconnect the vent control cables.
(8) Remove the fresh air intake grille from the
cowl.
(9) Remove the fresh air intake duct.
(10) Lower the windshield.
(11) Remove the defroster nozzle attaching screws
and remove the nozzle and duct.
INSTALLATION
(1) Install the defroster nozzle and duct.
(2) Raise and secure the windshield.
(3) Install the fresh air intake duct.
(4) Install the fresh air intake grille on the cowl.
(5) Install the vent cables.
(6) Position the heater housing on the dash panel.
Be sure all the housing studs extend through the
dash panel.
(7) Install the seals on the blower motor and the
heater core inlet and outlet tubes.
(8) Install the attaching nuts on the housing studs.
CAUTION: DO NOT over tighten the attaching nuts.
The housing could become distorted causing air
leaks and improper heater door operation. Tighten
the nuts alternately and evenly until 2 stud threads
are visible beyond each nut.
(9) Install the glove box.
(10) Connect the speedometer cable.
(11) Connect the heater hoses.
24 - 40 HEATING AND AIR CONDITIONINGJ

(12) Fill and bleed the cooling system.
FRESH AIR DOOR VACUUM MOTOR
REMOVAL
(1) Remove the glove box and assist handle.
(2) Disconnect the vacuum hose from the motor.
(3) Remove the motor lever retaining clip.
(4) Remove the motor attaching nuts and remove
the motor from the fresh air duct.
INSTALLATION
(1) Position the motor on the fresh air duct and in-
stall the motor attaching nuts.
(2) Align the motor lever with the air door lever
and install the lever retaining clip.
(3) Connect the vacuum hose to the motor.
(4) Install the glove box and assist handle.
FRESH AIR INTAKE DUCT
REMOVAL
WARNING: HOT ENGINE COOLANT CAN CAUSE
SEVERE BURNS. DO NOT OPEN THE RADIATOR
DRAIN COCK WHEN THE COOLING SYSTEM IS
HOT AND PRESSURIZED. ALLOW THE COOLANT
TO DECREASE TO ROOM TEMPERATURE BEFORE
STARTING REPAIR OPERATIONS.
(1) Drain approximately 1.9 liters (2 qts) of coolant
from the radiator. Drain the coolant into a clean con-
tainer.
(2) Disconnect the heater hoses.
(3) Remove the nuts attaching the heater housing
studs to the dash panel from inside the engine com-
partment.
(4) Disconnect the speedometer cable.
(5) Remove the glove box and assist handle.
(6) Tilt the heater housing back and pull it rear-
ward and out from under the instrument panel.
(7) Disconnect the vent cables.
(8) Remove the fresh air intake grille from the
cowl.
(9) Remove the fresh air intake duct.
INSTALLATION
(1) Install the fresh air intake duct.
(2) Install the defroster nozzle and duct.
(3) Raise and secure the windshield.
(4) Install the fresh air grille on the cowl.
(5) Install the vent cables.
(6) Position the heater housing on the dash panel.
Be sure all the housing studs extend through the
dash panel.
(7) Install the seals on the blower motor and
heater core inlet and outlet tubes.
(8) Install the attaching nuts on the heater hous-
ing studs.CAUTION: DO NOT over tighten the attaching nuts.
The housing could become distorted causing air
leaks and improper heater door operation. Tighten
the nuts alternately and evenly until 2 stud threads
are visible beyond each nut.
(9) Install the glove box and assist handle.
(10) Connect the speedometer cable.
(11) Connect the heater hoses.
(12) Fill and bleed the cooling system.
DESCRIPTION (AIR CONDITIONING)
The evaporator, blower fan and motor, thermostat,
expansion valve, capillary tube, air outlets and sys-
tem controls are located in the evaporator housing.
The evaporator housing is mounted under the instru-
ment panel. The compressor, condenser, receiver-
dryer and refrigerant lines are located in the engine
compartment.
A rotary-type compressor with magnetic clutch op-
erated drive pulley is used for all vehicles equipped
with air conditioning.
SIGHT GLASS
A sight glass is located on the top of the receiver-
drier (Fig. 6). The sight glass provides a visual check
of system refrigerant level. A continuous stream of
bubbles will appear in the sight glass when system
charge is low. Bubbles will not appear when the sys-
tem is fully charged.
A/C CONTROL PANEL
FAN SWITCH
The fan switch may be serviced by removing the
access plate located on the lower evaporator core
housing.
TEMPERATURE CONTROL THERMOSTAT
REMOVAL
(1) Lower the evaporator housing.
(2) Remove the attaching screws holding the top
and bottom housings together.
(3) Separate the housings.
(4) Remove the thermostat.
Fig. 6 Sight Glass (Typical)
JHEATING AND AIR CONDITIONING 24 - 41

INSTALLATION
(1) When installing a replacement temperature
control thermostat, insert the capillary tube into the
evaporator coil a minimum of 50 mm (2 inch) (Fig.
7).
CAUTION: Handle the tube with care to avoid bends
or kinks that could cause the thermostat to mal-
function.
(2) Assemble the housing and install the attaching
screws. DO NOT over tighten the attaching screws.
(3) Install the evaporator housing.
A/C CONDENSER
REMOVAL
WARNING: DO NOT LOOSEN THE RADIATOR
DRAIN COCK WHEN THE COOLING SYSTEM IS
HOT AND PRESSURIZED. HOT COOLANT CAN
CAUSE SERIOUS BURNS.
(1) Discharge the system slowly to prevent loss of
compressor oil.
(2) Drain the radiator. Drain the coolant into a
clean container.
(3) Remove the fan shroud and radiator.
(4) Disconnect the pressure pipe fitting from the
condenser.
(5) Remove the condenser attaching screws and tilt
the bottom of the condenser toward the engine.Plug
all the condenser openings to prevent entry of
dirt or moisture.
(6) Working from under the vehicle, disconnect the
receiver-drier to-evaporator hose fitting from the re-
ceiver-drier.
(7) Remove the condenser and receiver-drier as an
assembly.
(8) Remove the receiver-drier from the condenser,
if necessary.
INSTALLATION
(1) If the condenser is replaced, add 30 ml (1 fluid
oz.) of refrigerant oil to the system.(2) Attach the receiver-drier to the condenser.
(3) Place the condenser in position and connect the
hose fitting to the receiver-drier.
(4) Install the condenser attaching screws.
(5) Connect the condenser pressure pipe fitting.
(6) Install the radiator and fan shroud.
(7) Fill the cooling system.
(8) Evacuate, charge and leak test the air condi-
tioning system.
RECEIVER-DRIER REPLACEMENT
REMOVAL
(1) Discharge the system slowly to prevent loss of
compressor oil.
(2) Disconnect the evaporator and condenser hose
fittings from the receiver-drier.
(3) Remove the receiver-drier attaching screws. Re-
move the receiver-drier.
INSTALLATION
(1) Position the receiver-drier in place. Install and
tighten the receiver-drier attaching screws.
(2) Connect the evaporator and condenser hose fit-
tings to the receiver-drier.
(3) Charge the system.
(4) Preform the leak test on the system.
EVAPORATOR AND HOUSING
REMOVAL
(1) Discharge the system.Discharge the system
slowly to prevent loss of compressor oil.
(2) Disconnect the inlet (suction) hose.
(3) Disconnect the receiver-drier-to-evaporator
hoses.
(4) Remove the hose clamps and dash grommet re-
taining screws.
(5) Remove the evaporator housing-to-instrument
panel attaching screws and the housing mounting
bracket screw (Fig. 8).
Fig. 7 Temperature Control Thermostat
Fig. 8 Evaporator Housing
24 - 42 HEATING AND AIR CONDITIONINGJ

(6) Lower the evaporator housing and pull the
hoses and hose grommet through the dash opening.
The blower motor, blower motor housing, evapora-
tor core, control switches and expansion valve can all
be serviced after removing the evaporator housing
(Fig. 9).
INSTALLATION
(1) If the evaporator is replaced, add 30 ml (1 fluid
oz.) of refrigerant oil to the system.
(2) Push the hoses through the grommet openings
and install the hose grommet by pushing it toward
the engine compartment.
(3) Install the hose grommet attaching screws.
(4) Raise the evaporator housing. Install the evap-
orator housing-to- instrument panel attaching screws
and the evaporator housing mounting bracket screw.
(5) Install the hose clamps.
(6) Connect the receiver-drier hoses.
(7) Connect the inlet (suction) hose.
(8) Evacuate, charge and leak test the system.
EXPANSION (H) VALVE
REMOVAL
(1) Discharge the system slowly to prevent loss of
compressor oil.
(2) Remove the evaporator housing.
(3) Remove the insulation wrapped around the suc-
tion hose fitting, expansion valve and evaporator
tubing.(4) Mark the capillary tube location on the evapo-
rator tubing.
(5) Disconnect the inlet and outlet hose fittings,
and remove the capillary tube clamp.
(6) Disconnect and remove the expansion valve.
INSTALLATION
(1) Clean the evaporator tubing to provide a posi-
tive metal-to-metal contact for the replacement ex-
pansion valve capillary tube.
(2) Install the replacement expansion valve.
(3) Clamp the capillary tube at the marked loca-
tion on the evaporator tubing.
(4) Connect the inlet and outlet hose fittings.The
capillary tube must be securely clamped and
have positive metal-to-metal contact with the
evaporator tubing.
(5) Wrap the expansion valve, inlet hose fitting
and capillary tube with insulation.
(6) Install the evaporator housing.
(7) Evacuate, charge and leak test the system.
A/C BLOWER MOTOR
It is not necessary to discharge the system to ser-
vice the blower motor. The evaporator housing need
only be lowered for access to the blower motor at-
taching screws.
JHEATING AND AIR CONDITIONING 24 - 43

AIR CONDITIONING
CONTENTS
page page
AIR CONDITIONING EQUIPMENT........... 4
AIR CONDITIONING PERFORMANCE TESTS . . 5
GENERAL INFORMATION.................. 1
REFRIGERANT LEAK TESTING, DISCHARGING,
EVACUATING AND CHARGING............ 8REFRIGERANT OIL....................... 9
SERVICE PRECAUTIONS.................. 3
WARNINGS AND CAUTIONS FOR R134A
SYSTEM.............................. 3
GENERAL INFORMATION
A/C COMPONENTS
COMPRESSORÐThe SD-709 Compressor is used
on all models. The compressor compresses the low-
pressure refrigerant vapor from the evaporator into a
high pressure, high temperature vapor. The compres-
sor is serviced as an assembly only.
CLUTCH PULLEY AND COILÐThey are
mounted on the compressor and providing a way to
drive the compressor. The compressor clutch and coil
are the only serviced parts on the SD-709 compres-
sor. When the compressor is not in operation, the
pulley free wheels on the clutch hub bearing. When
the coil is energized the clutch plate is magnetically
engaged with the pulley and turns the compressor
shaft.
CONDENSERÐThe condenser is located in front
of the engine radiator. Its function is to cool the hot
high pressure refrigerant gas. This causes it to con-
dense into high pressure liquid refrigerant.
FILTER-DRIERÐThe drier is used to remove con-
taminates and traces of moisture from the refriger-
ant system.
SIGHT-GLASSÐThe sight glass is located on top
of the filter drier. It is used as a diagnostic tool to ob-
serve refrigerant flow.
LOW-PRESSURE HIGH-PRESSURE CUT-OFF
SWITCHÐThe switch is located on the filter drier
and is wired in series with compressor clutch. When
the pressure drops down to 193 kPa (28 psi) the
switch interrupts the power to the compressor clutch.
When the pressure increases above 3100 to 3375 kPa
(450 to 490 psi) the switch interrupts the power to
the compressor clutch.
HIGH PRESSURE RELIEF VALVEÐThe valve
is located on the filter drier. The valve is used to pre-
vent excessive pressure up build of 3445 to 4135
kPag (500 to 600 psi) and above. This will prevent
damage to the compressor and other system compo-
nents.EXPANSION VALVEÐThe expansion valve is lo-
cated in the engine compartment on XJ vehicles. On
YJ vehicles it is located behind the A/C housing. Its
function is to meter refrigerant into the evaporator in
accordance with cooling requirements.
EVAPORATOR COILÐThe coil is located in the
A/C housing. Its function is to remove heat and de-
humidify the air before it enters the vehicle.
FIN SENSING CYCLING CLUTCH SWITCHÐ
The switch is attached to the evaporator coil. This
switch prevents condensate water on the evaporator
coil from freezing. It does this by cycling the com-
pressor clutch on and off. This switch is used onXJ
only
THERMOSTATÐThe thermostat is located in the
evaporator housing. Its function is to cycle the com-
pressor clutch to control temperature. The thermo-
stat is used on theYJonly.
REFRIGERANT LINESÐThe lines are used to
carry the refrigerant between the various system
components.
SERVICE PORTSÐThe high pressure service
port is located on the discharge line near the com-
pressor. The low pressure service port is located on
the suction line near the compressor. The compressor
no longer uses service valves.
After servicing the refrigerant system, always in-
stall service port caps.
REFRIGERANT
The vehicles use a new type of refrigerant called
R-134a. It is a non-toxic, non-flammable, clear color-
less liquified gas.
R-134a refrigerant is not compatible with R-12 re-
frigerant in an air conditioning system. A small
amount of R-12 in a R-134a system will cause com-
pressor failure, refrigerant oil sludge or poor A/C per-
formance.
JAIR CONDITIONING1

AIR CONDITIONING PERFORMANCE TESTS
Humidity has an improtant bearing on the tempra-
ture of the air delivered to the vehicle's interior. It is
important to understand the effect humidity has on
the performance of the system. When humidity is
high, the evaporator has to perform a double duty. It
must lower the air temperature and the temperature
of the moisture carried in the air. Condensing the
moisture in the air transfers heat energy into the
evaporator fins and tubing. This reduces the amount
of heat the evaporator can absorb from the air. High
humidity greatly reduces the evaporator 's ability to
lower the temperature of the air.
Evaporator capacity used to reduce the amount of
moisture in the air is not wasted. Wringing some of
the moisture out of the air entering the vehicle adds
to the comfort of the passengers. However, an owner
may expect too much from their air conditioning sys-
tem on humid days. A performance test is the best
way to determine whether or not the system is per-
forming up to standard. This test also provides valu-
able clues to the possible cause of trouble.
PERFORMANCE TEST
Air temperature in test room must be 21ÉC (70ÉF)
minimum for this test.
(1) Connect a Tachometer and manifold gauge set.
(2) Set A/C controls to Max A/C, temperature lever
on full cool and blower on high.
(3) Start engine and adjust idle to 1,000 RPM with
A/C clutch engaged.
(4) Engine should be warmed up with doors, win-
dows and hood closed.(5) Insert a thermometer in the left center A/C out-
let. Operate the engine for 5 minutes. The A/C clutch
may cycle depending on ambient temperatures.
(6) After 5 minutes note the discharge air temper-
ature. If the clutch cycles, take the reading before
the clutch disengages.
(7) Open the hood and disconnect vacuum line go-
ing to the heater water control valve. Observe the
valve arm for movement as the line is disconnected.
If it does not move repair vacuum circuit. Plug the
vacuum line to prevent leakage.
(8) Operate the A/C for 2 more minutes and take
the discharge air temperature reading again. On XJ
vehicles if the temperature increased by more than
2ÉC (5ÉF) check the blend air door cable for correct
operation.
(9) Compare the discharge air temperature to the
A/C Performance (Temperature and Pressure) Chart.
If discharge air temperature is high, refer to Refrig-
erant Leak Testing and Refrigerant System Diagno-
sis Chart.
(10) Compare the compressor discharge and suc-
tion pressures to the A/C Performance (Temperature
and Pressure) Chart. If the discharge or suction pres-
sure is not normal, check the operation of the refrig-
erant system, referring to Refrigerant System
Diagnosis Chart.
The following charts have been developed for quick
reference.
YJ PERFORMANCE TEMPERATURE AND PRESSURE CHART
JAIR CONDITIONING5

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