Panel JEEP GRAND CHEROKEE 2003 WJ / 2.G Workshop Manual

Fig. 67 COWL PANEL TO FRONT FLOOR PAN
23 - 168 BODY STRUCTUREWJ
WELD LOCATIONS (Continued)

Fig. 69 COWL SIDE PANEL DASH INNER BODYSIDE AND OUTER BODYSIDE PANELS
23 - 170 BODY STRUCTUREWJ
WELD LOCATIONS (Continued)

Fig. 85 TAIL LAMP MOUNTING PANELS
23 - 184 BODY STRUCTUREWJ
WELD LOCATIONS (Continued)

Fig. 86 ROOF PANEL TO BODYSIDE APERTURE
WJBODY STRUCTURE 23 - 185
WELD LOCATIONS (Continued)

Fig. 87 ROOF PANEL TO REAR HEADER
23 - 186 BODY STRUCTUREWJ
WELD LOCATIONS (Continued)

Fig. 89 FRONT HEADER AND ROOF BOWS TO INNER PANEL
23 - 188 BODY STRUCTUREWJ
WELD LOCATIONS (Continued)

Fig. 90 FRONT SEAT/SHOULDER BELT TO INNER PANEL REINFORCEMENT
WJBODY STRUCTURE 23 - 189
WELD LOCATIONS (Continued)

Fig. 91 REAR SEAT/SHOULDER BELT TO INNER PANEL REINFORCEMENT
Fig. 92 FUEL FILLER GUSSET TO INNER QUARTER PANEL
23 - 190 BODY STRUCTUREWJ
WELD LOCATIONS (Continued)

HEATING & AIR CONDITIONING
TABLE OF CONTENTS
page page
HEATING & AIR CONDITIONING
DESCRIPTION
DESCRIPTION - COOLING SYSTEM
REQUIREMENTS.......................1
DESCRIPTION - HEATER AND AIR
CONDITIONER........................1
DESCRIPTION - REFRIGERANT SYSTEM
SERVICE PORT........................1
OPERATION
OPERATION - HEATER AND AIR
CONDITIONER........................2
OPERATION - REFRIGERANT SYSTEM
SERVICE PORT........................2DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - A/C
PERFORMANCE.......................2
DIAGNOSIS AND TESTING - HEATER
PERFORMANCE.......................6
STANDARD PROCEDURE - DIODE
REPLACEMENT.......................6
SPECIFICATIONS
A/C APPLICATION TABLE................7
TORQUE SPECIFICATIONS..............8
CONTROLS.............................9
DISTRIBUTION..........................36
PLUMBING.............................51
HEATING & AIR
CONDITIONING
DESCRIPTION
DESCRIPTION - COOLING SYSTEM
REQUIREMENTS
To maintain the performance level of the heating-
air conditioning system, the engine cooling system
must be properly maintained. The use of a bug
screen is not recommended. Any obstructions in front
of the radiator or condenser will reduce the perfor-
mance of the air conditioning and engine cooling sys-
tems.
The engine cooling system includes the heater core
and the heater hoses. Refer to Cooling for more infor-
mation before opening, or attempting any service to
the engine cooling system.
DESCRIPTION - HEATER AND AIR
CONDITIONER
A manual temperature control type heating-air
conditioning system is standard factory-installed
equipment on this model. An electronically controlled
Automatic Zone Control (AZC) type heating-air con-
ditioning system is an available factory-installed
option.
All vehicles are equipped with a common HVAC
housing assembly (Fig. 1). The system combines air
conditioning, heating, and ventilating capabilities in
a single unit housing mounted under the instrument
panel.DESCRIPTION - REFRIGERANT SYSTEM
SERVICE PORT
The two refrigerant system service ports are used
to charge, recover/recycle, evacuate, and test the air
conditioning refrigerant system. Unique service port
coupler sizes are used on the R-134a system to
ensure that the refrigerant system is not accidentally
contaminated by the use of the wrong refrigerant
(R-12), or refrigerant system service equipment.
Fig. 1 Blend-Air HVAC System - (typical)
1 - Blend Door
2 - Expansion Valve
3 - Evaporator Core
4 - Blower Assembly
5 - Recirculation Door
6 - Evaporator Probe
7 - Heater Core
8 - Heat/Defrost Door
9 - Panel/Defrost Door
WJHEATING & AIR CONDITIONING 24 - 1

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)