tow JEEP GRAND CHEROKEE 2002 WJ / 2.G Workshop Manual

ING & AIR CONDITIONING/CONTROLS/A/C
PRESSURE TRANSDUCER - INSTALLATION).
(9) Evacuate the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE)
(10) Charge the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
(11) Connect the negative battery cable.
INSTALLATION
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
Any kinks or sharp bends in the refrigerant plumb-
ing will reduce the capacity of the entire air condi-
tioning system. Kinks and sharp bends reduce the
flow of refrigerant in the system. A good rule for the
flexible hose refrigerant lines is to keep the radius of
all bends at least ten times the diameter of the hose.
In addition, the flexible hose refrigerant lines should
be routed so they are at least 80 millimeters (3
inches) from the exhaust manifold.
High pressures are produced in the refrigerant sys-
tem when the air conditioning compressor is operat-
ing. Extreme care must be exercised to make sure
that each of the refrigerant system connections is
pressure-tight and leak free. It is a good practice to
inspect all flexible hose refrigerant lines at least once
a year to make sure they are in good condition and
properly routed.
(1) Remove the tape or plugs from the discharge
line block fitting and the manifold on the compressor.
Install the discharge line block fitting to the manifold
on the compressor. Tighten the mounting bolt to 25.4
N´m (225 in. lbs.).
(2) Remove the tape or plugs from the refrigerant
line fittings on the condenser inlet and the discharge
line. Connect the discharge line to the condenser
inlet. Tighten the retaining nut to 28 N´m (250 in.
lbs.).
(3) Install the a/c high pressure transducer(Refer
to 24 - HEATING & AIR CONDITIONING/CON-
TROLS/A/C PRESSURE TRANSDUCER - INSTAL-
LATION).
(4) Connect the battery negative cable.
(5) Evacuate the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE)(6) Charge the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
A/C EXPANSION VALVE
DESCRIPTION
The ªHº valve type thermal expansion valve (TXV)
is located at the front of the heater-A/C housing
between the liquid and suction lines and the evapo-
rator coil.
The expansion valve is a factory calibrated unit
and cannot be adjusted or repaired. If faulty or dam-
aged, the expansion valve must be replaced.
OPERATION
High-pressure, high temperature liquid refrigerant
from the liquid line passes through the expansion
valve orifice, converting it inot a low-pressure, low-
temperature mixture of liquid and gas before it
enters the evaporator coil. A temperature sensor in
the expansion valve control head monitors the tem-
perature of the refrigerant leaving the evaporator coil
throught the suction line, and adjusts the orifice size
at the liquid line to let the proper amoount of refrig-
erant into the evaporator coil to meet the vehicle
cooling requirements. Controlling the refrigerant flow
through the evaporator ensures that none of the
refrigerant leaving the evaporator is still in a liquid
state, which could damage the compressor.
DIAGNOSIS AND TESTING - A/C EXPANSION
VALVE
The expansion valve is located on the engine side
of the dash panel near the shock tower.
The expansion valve can fail in three different
positions (open, closed or restricted).
In an Open Position: this will result in a noisy
compressor or no cooling. The cause can be broken
spring, broken ball or excessive moisture in the A/C
system. If the spring or ball are found to be defective,
replace the expansion valve. If excessive moisture is
found in the A/C system, recycle the refrigerant.
In a Closed Position: There will be low suction
pressure and no cooling. This may be caused by a
failed power dome or excessive moisture in the A/C
system. If the power dome on the expansion valve is
found to be defective replace the expansion valve. If
excessive moisture is found recycle the refrigerant.
A Restricted Orifice: There will be low suction
pressure and no cooling. This may be caused by
debris in the refrigerant system. If debris is believed
to be the cause, recycle the refrigerant and replace
the expansion valve and the receiver/drier.
WJPLUMBING 24 - 65
A/C DISCHARGE LINE (Continued)

(8)Do not attempt to clean the old PCV valve.
(9) Return PCV valve back to oil filler tube by
placing valve locating tabs (Fig. 21) into cam lock.
Press PCV valve in and rotate valve upward. A slight
click will be felt when tabs have engaged cam lock.
Valve should be pointed towards rear of vehicle.
(10) Connect PCV line/hose and connecting rubber
hose to PCV valve.
(11) Disconnect rubber hose from fresh air fitting
at left side of air cleaner resonator box (Fig. 22).
Start engine and bring to idle speed. Hold a piece of
stiff paper (such as a parts tag) loosely over the
opening of the disconnected rubber hose.
(12) The paper should be drawn against the hose
opening with noticeable force. This will be after
allowing approximately one minute for crankcase
pressure to reduce.
(13) If vacuum is not present, disconnect each PCV
system hose at top of each breather (Fig. 22). Check
for obstructions or restrictions.(14) If vacuum is still not present, remove each
PCV system breather (Fig. 22) from each cylinder
head. Check for obstructions or restrictions. If
plugged, replace breather. Tighten breather to 12
N´m (106 in. lbs.) torque. Do not attempt to clean
breather
(15) If vacuum is still not present, disconnect each
PCV system hose at each fitting and check for
obstructions or restrictions.
Fig. 21 PCV Valve/Oil Filler TubeÐ4.7L V-8 Engine
1 - O-RING
2 - LOCATING TABS
3 - CAM LOCK
4 - OIL FILLER TUBE
5 - PCV LINE/HOSE
6 - P C V VA LV E
Fig. 22 PCV Breathers/Tubes/HosesÐ4.7L V-8
Engine
1 - FRESH AIR FITTING
2 - CONNECTING TUBES/HOSES
3 - CRANKCASE BREATHERS (2)
4 - RUBBER HOSE
5 - AIR CLEANER RESONATOR
25 - 38 EVAPORATIVE EMISSIONSWJ
PCV VALVE (Continued)

REMOVAL - PCV VALVE - 4.7L
The PCV valve is located on the oil filler tube (Fig.
23). Two locating tabs are located on the side of the
valve (Fig. 23). These 2 tabs fit into a cam lock in the
oil filler tube. An o-ring seals the valve to the filler
tube.
(1) Disconnect PCV line/hose (Fig. 23) by discon-
necting rubber hose at PCV valve fitting.
(2) Remove PCV valve at oil filler tube by rotating
PCV valve downward (counter-clockwise) until locat-
ing tabs have been freed at cam lock (Fig. 23). After
tabs have cleared, pull valve straight out from filler
tube.To prevent damage to PCV valve locating
tabs, valve must be pointed downward for
removal. Do not force valve from oil filler tube.
(3) After valve is removed, check condition of valve
o-ring (Fig. 23).
INSTALLATION - PCV VALVE - 4.7L
The PCV valve is located on the oil filler tube (Fig.
23). Two locating tabs are located on the side of the
valve (Fig. 23). These 2 tabs fit into a cam lock in the
oil filler tube. An o-ring seals the valve to the filler
tube.
(1) Return PCV valve back to oil filler tube by
placing valve locating tabs (Fig. 23) into cam lock.
Press PCV valve in and rotate valve upward. A slight
click will be felt when tabs have engaged cam lock.
Valve should be pointed towards rear of vehicle.
(2) Connect PCV line/hose and rubber hose to PCV
valve.
VACUUM LINES
DESCRIPTION
A vacuum schematic for emission related items can
be found on the VECI label. Refer to Vehicle Emis-
sion Control Information (VECI) Label for label loca-
tion.
VAPOR CANISTER
DESCRIPTION
A maintenance free, EVAP canister is used on all
gasoline powered models. The canister is attached to
a two-piece support bracket located behind the left-
rear wheel.
OPERATION
The EVAP canister is filled with granules of an
activated carbon mixture. Fuel vapors entering the
EVAP canister are absorbed by the charcoal granules.
The canister serves two functions: as a temporary
fuel vapor storage point while refueling the vehicle
for the ORVR system, as a temporary vapor storage
point while the engine is running.
Fuel tank pressure vents into the EVAP canister.
Fuel vapors are temporarily held in the canister until
they can be drawn into the intake manifold. The duty
cycle EVAP canister purge solenoid allows the EVAP
canister to be purged at predetermined times and at
certain engine operating conditions.
Refer to ORVR for additional information.
Fig. 23 PCV Valve/Oil Filler Tube Location
1 - O-RING
2 - LOCATING TABS
3 - CAM LOCK
4 - OIL FILLER TUBE
5 - PCV LINE/HOSE
6 - P C V VA LV E
WJEVAPORATIVE EMISSIONS 25 - 39
PCV VALVE (Continued)