2003 JEEP GRAND CHEROKEE ods

SEALER LOCATIONS
SPECIFICATIONS
SEALER LOCATIONS
INDEX
DESCRIPTION FIGURE
APPLICATION METHODS 6
COWL PLENUM AND DASH PANEL 7
DASH, COWL AND PLENUM 8
INNER FENDER AND COWL 9
LOWER PLENUM AND BAFFLE 10
A-PILLAR 11
COWL SIDE ATTACHMENT 12
BODYSIDE ATTACHMENT 13
BODYSIDE INNER AND OUTER TO COWL 14
FENDER ATTACHMENT 15
DOOR HINGE BOLT HOLES 16
A-PILLAR AND B-PILLAR HINGE AREA 17
B-PILLAR AND SILL 18
SILL AND B-PILLAR 19
BODYSIDE APERTURE AND REAR WHEELHOUSE 20
FUEL FILLER GUSSET 21
OUTER WHEELHOUSE FLANGE 22
LIFTGATE OPENING 23
INNER WHEELHOUSE FLANGE TO BODYSIDE APERTURE 24
WHEELHOUSE LOWER 25
REAR INNER CROSSMEMBER 26
ROOF TO BODY SIDE APERTURE 27
23 - 118 BODY STRUCTUREWJ

Fig. 6 APPLICATION METHODS
WJBODY STRUCTURE 23 - 119
SEALER LOCATIONS (Continued)

OPERATION
OPERATION - HEATER AND AIR CONDITIONER
Outside fresh air enters the vehicle through the
cowl top opening at the base of the windshield, and
passes through a plenum chamber to the HVAC sys-
tem blower housing. Air flow velocity can then be
adjusted with the blower motor speed selector switch
on the a/c heater control panel. The air intake open-
ings must be kept free of snow, ice, leaves, and other
obstructions for the HVAC system to receive a suffi-
cient volume of outside air.
It is also important to keep the air intake openings
clear of debris because leaf particles and other debris
that is small enough to pass through the cowl ple-
num screen can accumulate within the HVAC hous-
ing. The closed, warm, damp and dark environment
created within the HVAC housing is ideal for the
growth of certain molds, mildews and other fungi.
Any accumulation of decaying plant matter provides
an additional food source for fungal spores, which
enter the housing with the fresh air. Excess debris,
as well as objectionable odors created by decaying
plant matter and growing fungi can be discharged
into the passenger compartment during HVAC sys-
tem operation.
Both the manual and AZC heater and air condi-
tioner are blend-air type systems. In a blend-air sys-
tem, a blend door controls the amount of
unconditioned air (or cooled air from the evaporator)
that is allowed to flow through, or around, the heater
core. A temperature control knob on the a/c heater
control panel determines the discharge air tempera-
ture by energizing the blend door actuator, which
operates the blend door. This allows an almost imme-
diate control of the output air temperature of the sys-
tem. The AZC system will have separate blend doors
and temperature controls for each front seat occu-
pant.
The mode control knob on the a/c heater control
panel is used to direct the conditioned air to the
selected system outlets. On manual temperature con-
trol systems, the mode control knob switches engine
vacuum to control the mode doors, which are oper-
ated by vacuum actuators. On AZC systems, the
mode control knob switches electrical current to con-
trol the mode doors, which are operated by electronic
actuators.
The outside air intake can be shut off on manual
temperature control systems by selecting the Recircu-
lation Mode with the mode control knob. The outside
air intake can be shut off on Automatic Zone Control
(AZC) type system by pushing the Recirculation
Mode button. This will operate the recirculation door
that closes off the outside fresh air intake and recir-
culates the air that is already inside the vehicle.The air conditioner for all models is designed for
the use of non-CFC, R-134a refrigerant. The air con-
ditioning system has an evaporator to cool and dehu-
midify the incoming air prior to blending it with the
heated air. This air conditioning system uses a ther-
mal expansion valve to meter refrigerant flow to the
evaporator coil. To maintain minimum evaporator
temperature and prevent evaporator freezing, the
system utilizes an evaporator thermister probe with
the appropriate operating logic located in the body
control module (BCM).
OPERATION - REFRIGERANT SYSTEM SERVICE
PORT
The high pressure service port is located on the liq-
uid line near the receiver/drier. The low pressure ser-
vice port is located on the suction line near the
evaporator at the rear of the engine compartment.
Each of the service ports has a threaded plastic
protective cap installed over it from the factory. After
servicing the refrigerant system, always reinstall
both of the service port caps.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - A/C
PERFORMANCE
The air conditioning system is designed to provide
the passenger compartment with low temperature
and low specific humidity air. The evaporator, located
in the HVAC housing on the dash panel below the
instrument panel, is cooled to temperatures near the
freezing point. As warm damp air passes through the
cooled evaporator, the air transfers its heat to the
refrigerant in the evaporator and the moisture in the
air condenses on the evaporator fins. During periods
of high heat and humidity, an air conditioning sys-
tem will be more effective in the Recirculation Mode.
With the system in the Recirculation Mode, only air
from the passenger compartment passes through the
evaporator. As the passenger compartment air dehu-
midifies, the air conditioning system performance
levels improve.
Humidity has an important bearing on the tempera-
ture of the air delivered to the interior of the vehicle. It
is important to understand the effect that humidity has
on the performance of the air conditioning system.
When humidity is high, the evaporator has to perform a
double duty. It must lower the air temperature, and it
must lower the temperature of the moisture in the air
that condenses on the evaporator fins. Condensing the
moisture in the air transfers heat energy into the evap-
orator fins and tubing. This reduces the amount of heat
the evaporator can absorb from the air. High humidity
greatly reduces the ability of the evaporator to lower
the temperature of the air.
24 - 2 HEATING & AIR CONDITIONINGWJ
HEATING & AIR CONDITIONING (Continued)

controlled vehicle accessories during periods of low
engine vacuum such as when the vehicle is climbing
a steep grade, or under other high engine load oper-
ating conditions.
The vacuum reservoir cannot be repaired and, if
faulty or damaged, it must be replaced.
REMOVAL
(1) Remove the right side headlamp mounting
module and headlamp assembly. Refer to Lamps/
Lighting for the procedures.
(2) Remove the two screws that secure the vacuum
reservoir to the base of the radiator closure panel.
(3) Remove the vacuum reservoir.
INSTALLATION
(1) Install the vacuum reservoir in the vehicle and
tighten the two screws to 3.4 N´m (30 in. lbs.).
(2) Install the right side headlamp mounting mod-
ule and headlamp assembly. Refer to Lamps/Lighting
for the procedures.
EVAPORATOR TEMPERATURE
SENSOR
DESCRIPTION
The evaporator probe is a 2 wire temperature sens-
ing element located at the coldest point on the face of
the evaporator. The switch is attached to the evapo-
rator coil fins. The evaporator temperature probe
prevents condensate water on the evaporator coil
from freezing and obstructing A/C system air flow.
OPERATION
The probe is used to switch the clutch OFF before
evaporator freeze-up occurs. Output from the probe is
sampled by the Body Control Module (BCM). The
clutch is switched OFF when the probe temperature
reaches 1.1É C (34É F). It is allowed to switch ON
when the probe temperature reaches 2.2É C (36É F).
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the HVAC housing from the vehi-
cle(Refer to 24 - HEATING & AIR CONDITIONING/
DISTRIBUTION/HVAC HOUSING - REMOVAL).
(3) Disassemble the HVAC housing(Refer to 24 -
HEATING & AIR CONDITIONING/DISTRIBUTION/
HVAC HOUSING - DISASSEMBLY).
(4) Carefully pull the probe out of the evaporator
core.
INSTALLATION
(1) Install the new probe into the evaporator.
NOTE: The new probe must not go into the same
hole (in the evaporator core) that the old probe was
removed from.
(2) Reassemble the HVAC housing(Refer to 24 -
HEATING & AIR CONDITIONING/DISTRIBUTION/
HVAC HOUSING - ASSEMBLY).
(3) Reinstall the HVAC assembly in the vehicle(Re-
fer to 24 - HEATING & AIR CONDITIONING/DIS-
TRIBUTION/HVAC HOUSING - INSTALLATION).
(4) Reconnect the battery negative cable.
Fig. 22 VACUUM RESERVOIR
1 - FAN RELAY
2 - SPEED CONTROL SERVO
3 - VACUUM RESERVOIR
WJCONTROLS 24 - 35
VACUUM RESERVOIR (Continued)

moisture which may have netered and become
trapped within the refrigerant system. In addition,
during periods of high demand air conditioner opera-
tion, the filter-drier acts as a reservoir to store sur-
plus refrigerant. Refrigerant enters the filter-drier as
a high-pressure, low-temperature liquid.
REMOVAL
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)
(1) Recover the refrigerant from the refrigerant
system(Refer to 24 - HEATING & AIR CONDITION-
ING/PLUMBING - STANDARD PROCEDURE).
(2) Remove the battery and the battery tray(Refer
to 8 - ELECTRICAL/BATTERY SYSTEM/BATTERY -
REMOVAL) and (Refer to 8 - ELECTRICAL/BAT-
TERY SYSTEM/TRAY - REMOVAL).
(3) Remove the screw from the receiver/drier
bracket (Fig. 15) or (Fig. 16).
(4) Remove the retaining nut from the evaporator
connection and then slide the suction line off the
stud and liquid line.
(5) Remove the receiver/drier bracket from the
stud and disconnect the liquid line from the evapora-tor inlet. Install plugs in or tape over all of the evap-
orator connection openings and opened refrigerant
line fittings.
(6) Disconnect the liquid line from the condenser
outlet. Install plugs in, or tape over all of the opened
refrigerant line fittings.
(7) Remove liquid line assembly.
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
Fig. 14 HEATER CORE, TUBES, AND O-RINGS
1 - HEATER CORE TUBES
2 - TUBE-TO-CORE CLAMPS
3 - SCREWS
4 - O-RINGS
5 - HEATER CORE
Fig. 15 COMPRESSOR AND A/C LINES - V8
1 - DISCHARGE LINE
2 - A/C COMPRESSOR
3 - SUCTION LINE
4 - A/C/ CONDENSOR
5 - DISCHARGE LINE TO CONDENSOR
6 - A/C PRESSURE TRANSDUCER SWITCH
7 - A/C/ SERVICE PORT
8 - RECEIVER DRIER
WJPLUMBING 24 - 73
RECEIVER / DRIER (Continued)

During periods of high manifold vacuum, such as
idle or cruising speeds, vacuum is sufficient to com-
pletely compress spring. It will then pull the plunger
to the top of the valve (Fig. 6). In this position there
is minimal vapor flow through the valve.
During periods of moderate manifold vacuum, the
plunger is only pulled part way back from inlet. This
results in maximum vapor flow through the valve
(Fig. 7).
SPECIFICATIONS
TORQUE - EVAPORATION SYSTEM
DESCRIPTION N-m Ft. Lbs. In. Lbs.
Crankcase Breathers - 3.7L /
4.7L12 - 106
EVAP Canister Mounting 11 - 100
EVAP Canister Purge
Solenoid Mounting Nuts9- 80
LDP Pump-to-Support Bracket 2 - 20
LDP Pump Support
Bracket-to-Frame28 - 250
Fig. 5 Engine Off or Engine Pop-BackÐNo Vapor
FlowFig. 6 High Intake Manifold VacuumÐMinimal Vapor
Flow
Fig. 7 Moderate Intake Manifold VacuumÐMaximum
Vapor Flow
WJEVAPORATIVE EMISSIONS 25 - 27
EVAPORATIVE EMISSIONS (Continued)