1995 JEEP YJ Service And Repair Manual

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JEEP YJ 1995 Service And Repair Manual HEATING AND AIR CONDITIONING
CONTENTS
page page
COMPONENT SERVICEÐXJ VEHICLES...... 23
COMPONENT SERVICEÐYJ VEHICLES...... 32
COMPRESSOR SERVICE.................. 19
GENERAL INFORMATION.............

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JEEP YJ 1995 Service And Repair Manual HEATING SCHEMATICÐXJ
24 - 2 HEATING AND AIR CONDITIONINGJ

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JEEP YJ 1995 Service And Repair Manual HEATERÐYJ
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 air control lever (Fig. 1) operates a door

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JEEP YJ 1995 Service And Repair Manual 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 con-
trol lever. Fresh air intake occurs only wh

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 con-
trol lever. Fresh air intake occurs only when the le-
ver is in the VENT position.
AIR CONDITIONING
The compressor increases the pressure and temper-
ature of the refrigerant. The heated refrigerant vapor
is pumped into the condenser where it is cooled by
air passing over the condenser fins. As the refriger-
ant cools in the condenser, it condenses into a liquid.
Still under high pressure, the liquid refrigerant
passes into the receiver. The receiver acts as a reser-
voir to furnish refrigerant to the expansion valve at
all times. From the receiver, the high pressure liquid
refrigerant passes to the expansion valve. The expan-
sion valve meters refrigerant into the evaporator.
The low pressure is maintained by the suction side of
the compressor. As it enters the evaporator, the re-
frigerant begins to absorb heat from the air passing
over the evaporator core. Having given up its heat to
boil the refrigerant, the air is cooled and passes into
the passenger compartment. From the evaporator the
vaporized refrigerant is drawn back to the compres-
sor to repeat the cycle.
A/C COMPONENTS
COMPRESSOR:The SD7H15 Compressor is used
on all models. The purpose of the compressor is to
compress the low-pressure refrigerant vapor into a
high pressure, high temperature vapor. The compres-
sor is serviced as a assembly only.
CLUTCH PULLEY AND COIL:They 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 SD7H15 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.
CONDENSER:The 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.
EXPANSION VALVE:The 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.
Fig. 3 Fresh Air Intake System Components
24 - 4 HEATING AND AIR CONDITIONINGJ

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JEEP YJ 1995 Service And Repair Manual AIR CONDITIONING SCHEMATICÐXJ
JHEATING AND AIR CONDITIONING 24 - 5

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JEEP YJ 1995 Service And Repair Manual EVAPORATIVE HOUSING COMPONENTSÐYJ
24 - 6 HEATING AND AIR CONDITIONINGJ

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JEEP YJ 1995 Service And Repair Manual EVAPORATOR COIL:The 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 SWITCH:
The switch is attached

EVAPORATOR COIL:The 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 SWITCH:
The switch is attached to the evaporator coil with the
temperature sensing probe inserted into the coil fins.
This switch controls evaporator temperature and pre-
vents condensate water on the evaporator coil from
freezing. It does this by sending signals to the Pow-
ertrain Control Module (PCM) to cycling the com-
pressor clutch on and off. This switch is used onXJ
only.
FILTER-DRIER:The drier is used to remove any
traces of moisture from the refrigerant system. A
sight glass is located on top of the filter drier. It is
used as a diagnostic tool to observe refrigerant flow.
HIGH PRESSURE RELIEF VALVE:The valve is
located on the filter drier. The valve is used to pre-
vent excessive high pressure build of 3445 to 4135
kPa (500 to 600 psi) and above. This prevents dam-
age to the compressor and other system components.
LOW-PRESSURE HIGH-PRESSURE CUT-OFF
SWITCH:The 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.
THERMOSTAT:The thermostat is located in the
evaporator housing. The thermostat temperature
sensing probe is inserted into the evaporator coil. Its
function is to cycles the compressor clutch on and off.
This switch controls temperature and prevents con-
densate water on the evaporator coil from freezing.
The thermostat is used on theYJonly.
REFRIGERANT LINES:The lines are used to
carry the refrigerant between the various system
components.
SERVICE PORTS:The high pressure service port
is located on the discharge line near the compressor.
The low pressure service port is located on the suc-
tion line near the compressor. These ports are used
to attach A/C gauges. After servicing the refrigerant
system, always install service port caps.
REFRIGERANT
XJ and YJ 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. A small amount of R-12 in a R-134a system
will cause compressor failure, oil sludge or poor air
conditioning performance.R-134a refrigerant requires a special type of com-
pressor oil (SP20 PAG). When adding oil, make sure
that it is designed to be used in a R-134a system and
the SD7H15 compressor.
Service ports have been designed to ensure that
the system is not accidentally filled with R-12 refrig-
erant.
REFRIGERANT EQUIPMENT
WARNING: EYE PROTECTION MUST BE USED
WHEN SERVICING AN AIR CONDITIONING REFRIG-
ERANT SYSTEM. TURN OFF (ROTATE CLOCKWISE)
ALL VALVES ON THE EQUIPMENT BEING USED
BEFORE PROCEEDING WITH THIS OPERATION.
PERSONNEL INJURY CAN RESULT.
Chrysler Corporation recommends a (R-134a) recy-
cling device that meets SAE standard J2210 be used
when servicing the refrigerant system. Contact an
automotive service equipment supplier for refrigerant
recycling equipment that is available in your area.
Refer to the operating instructions provided with the
recycling equipment for proper operation.
MANIFOLD GAUGE SET
CAUTION: DO NOT use an R-12 manifold gauge set
on an R-134a system. The refrigerants are not com-
patible and system damage will result.
A manifold gauge set (Fig. 1) may be needed in
conjunction with the charging and or recovery/recy-
cling device. The service hoses on the gauge set being
used should have manual (turn wheel) or automatic
back flow valves at the service port connector ends.
This will prevent refrigerant from being release into
the atmosphere.
LOW PRESSURE GAUGE HOSE
The low pressure hose (BLUE with BLACK STRIP)
should be attached to the charging/service port. This
port is located at the right front of the engine com-
partment in the condenser-to-evaporator line.
HIGH PRESSURE GAUGE HOSE
The high pressure hose (RED with BLACK STRIP)
should be attached to the discharge/service port. This
port is located on the compressor plumbing or mani-
fold.
RECOVERY/RECYCLING/EVACUATION/
CHARGING HOSE
The center manifold hose (YELLOW or WHITE
with BLACK STRIP) is used to recover, evacuate and
charge the refrigerant system. When the low or high
pressure valves on the manifold gauge set are
opened, the refrigerant in the system will escape
through this hose.
JHEATING AND AIR CONDITIONING 24 - 7

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JEEP YJ 1995 Service And Repair Manual Refer to the Recovery/Recycling device operators
manual for proper procedures.
Fig. 1 Manifold Gauge Set
24 - 8 HEATING AND AIR CONDITIONINGJ

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