Heated seat JEEP GRAND CHEROKEE 2003 WJ / 2.G Owner's Guide

DRIVER DOOR MODULE C3 - BLACK 4 WAY
CAV CIRCUIT FUNCTION
1 BK MEMORY SWITCH RETURN
2 BR MEMORY SWITCH MUX
3 OR MEMORY SET INDICATOR DRIVER
4 GY SWITCH ILLUMINATION DRIVER
DRIVER FRONT DOOR COURTESY LAMP - BLACK 2 WAY
CAV CIRCUIT FUNCTION
1 M21 20PK/DG COURTESY LAMP DRIVER
2 L121 20BK/RD COURTESY LAMP GROUND
DRIVER FRONT POWER WINDOW MOTOR - BLACK 2 WAY
CAV CIRCUIT FUNCTION
1 Q21 16WT DRIVER WINDOW DRIVER (DOWN)
2 Q11 16LB DRIVER WINDOW DRIVER (UP)
DRIVER HEATED SEAT BACK (PREMIUM I/III)-3WAY
CAV CIRCUIT FUNCTION
1 P88 16BK/BR HEATED SEAT DRIVER
2 Z6 16BK/YL GROUND
3- -
DRIVER HEATED SEAT CUSHION (PREMIUM I/III)-4WAY
CAV CIRCUIT FUNCTION
1 P131 16BK/OR DRIVER SEAT HEATER B(+) DRIVER
2 P88 16BK/BR HEATED SEAT DRIVER
3 P135 20LB/BK DRIVER SEAT TEMPERATURE SENSOR INPUT
4 P29 20BR/WT SEAT SENSOR 5 VOLT SUPPLY
WJ8W-80 CONNECTOR PIN-OUT 8W - 80 - 69

DRIVER HEATED SEAT SWITCH - WHITE 6 WAY
CAV CIRCUIT FUNCTION
1 P133 20TN/DG DRIVER SEAT HEATER SWITCH MUX
2 E2 20OR PANEL LAMPS DRIVER
3 F22 20WT/PK FUSED IGNITION SWITCH OUTPUT (RUN)
4- -
5 Z300 20BK GROUND
6 P132 20OR/BK SEAT HEATER SWITCH SENSOR GROUND
DRIVER LUMBAR MOTOR (MIDLINE/PREMIUM) - BLACK 2 WAY
CAV CIRCUIT FUNCTION
1 P105 16LG/DB LUMBAR FORWARD SWITCH SENSE
2 P104 16YL/RD LUMBAR REARWARD SWITCH SENSE
DRIVER LUMBAR SWITCH (MIDLINE/PREMIUM) - WHITE 6 WAY
CAV CIRCUIT FUNCTION
1- -
2 Z238 16BK (RHD) GROUND
2 Z243 16BK (LHD) GROUND
3 P105 16LG/DB (RHD) LUMBAR FORWARD SWITCH SENSE
3 P104 16YL/RD (LHD) LUMBAR REAR WARD SWITCH SENSE
4 P104 16YL/RD (RHD) LUMBAR REAR WARD SWITCH SENSE
4 P105 16LG/DB (LHD) LUMBAR FORWARD SWITCH SENSE
5 Z238 16BK (RHD) GROUND
5 Z243 16BK (LHD) GROUND
6 F35 16RD FUSED B(+)
DRIVER POWER MIRROR - BLACK 12 WAY
CAV CIRCUIT FUNCTION
1 C117 20BK MIRROR HEATER 12 VOLT SUPPLY
2 P65 20DG MIRROR HORIZONTAL POSITION SIGNAL
3 P69 20GY MIRROR SENSOR GROUND
4 P64 20VT MIRROR VERTICAL POSITION SIGNAL
5 C118 20BK/WT MIRROR HEATER GROUND
6 P95 20OR MIRROR HORIZONTAL DRIVER
7 P114 20YL/RD AUTO DAY/NIGHT MIRROR(-)
8 P99 20DB (BUILT-UP-EXPORT) FOLDING MIRROR FEED
9 P110 20YL (BUILT-UP-EXPORT) FOLDING MIRROR RETURN
10 P112 20YL/WT AUTO DAY/NIGHT MIRROR(+)
11 P93 20RD MIRROR VERTICAL DRIVER
12 P91 20WT MIRROR COMMON DRIVER
8W - 80 - 70 8W-80 CONNECTOR PIN-OUTWJ

PASSENGER DOOR MODULE C2 - BLACK 12 WAY
CAV CIRCUIT FUNCTION
1 P95 20OR MIRROR HORIZONTAL DRIVER
2 C118 20BK/WT MIRROR HEATER GROUND
3 P64 20VT MIRROR VERTICAL POSITION SIGNAL
4 P69 20GY MIRROR SENSOR GROUND
5 P65 20DG MIRROR HORIZONTAL POSITION SIGNAL
6 C117 20BK MIRROR HEATER 12 VOLT SUPPLY
7 P91 20WT MIRROR COMMON DRIVER
8 P93 20RD MIRROR VERTICAL DRIVER
9 M21 20PK/DG COURTESY LAMP DRIVER
10 P110 20YL (BUILT-UP-EXPORT) FOLDING MIRROR RETURN
11 P99 20DB (BUILT-UP-EXPORT) FOLDING MIRROR FEED
12 L121 20BK/RD COURTESY LAMP GROUND
PASSENGER FRONT DOOR COURTESY LAMP - BLACK 2 WAY
CAV CIRCUIT FUNCTION
1 M21 20PK/DG COURTESY LAMP DRIVER
2 L121 20BK/RD COURTESY LAMP GROUND
PASSENGER FRONT POWER WINDOW MOTOR - BLACK 2 WAY
CAV CIRCUIT FUNCTION
1 Q22 16VT PASSENGER WINDOW DRIVER (DOWN)
2 Q12 16BR PASSENGER WINDOW DRIVER (UP)
PASSENGER HEATED SEAT BACK (PREMIUM I/III)-3WAY
CAV CIRCUIT FUNCTION
1 P88 16BK/BR HEATED SEAT DRIVER
2 Z5 16BK/VT GROUND
3- -
WJ8W-80 CONNECTOR PIN-OUT 8W - 80 - 103

PASSENGER HEATED SEAT CUSHION (PREMIUM I/III)-4WAY
CAV CIRCUIT FUNCTION
1 P130 16DG/WT PASSENGER SEAT HEATER B(+) DRIVER
2 P88 16BK/BR HEATED SEAT DRIVER
3 P86 20DG/YL PASSENGER SEAT TEMPERATURE SENSOR INPUT
4 P29 20BR/WT SEAT SENSOR 5 VOLT SUPPLY
PASSENGER HEATED SEAT SWITCH - BLACK 6 WAY
CAV CIRCUIT FUNCTION
1 P134 20TN/LG PASSENGER SEAT HEATER SWITCH MUX
2 E2 20OR PANEL LAMPS DRIVER
3 F22 20WT/PK FUSED IGNITION SWITCH OUTPUT (RUN)
4- -
5 Z300 20BK GROUND
6 P132 20OR/BK SEAT HEATER SWITCH SENSOR GROUND
PASSENGER LUMBAR MOTOR (MIDLINE/PREMIUM) - BLACK 2 WAY
CAV CIRCUIT FUNCTION
1 P105 16LG/DG LUMBAR FORWARD SWITCH SENSE
2 P104 16YL/RD LUMBAR REARWARD SWITCH SENSE
PASSENGER LUMBAR SWITCH (MIDLINE/PREMIUM) - WHITE 6 WAY
CAV CIRCUIT FUNCTION
1- -
2 Z1 16BK GROUND
3 P104 16YL/RD (RHD) LUMBAR REARWARD SWITCH SENSE
3 P105 16LG/DB (LHD) LUMBAR FORWARD SWITCH SENSE
4 P105 16LG/DB (RHD) LUMBAR FORWARD SWITCH SENSE
4 P104 16YL/RD (LHD) LUMBAR REARWARD SWITCH SENSE
5 Z1 16BK GROUND
6 F37 16RD/LB FUSED B(+)
8W - 80 - 104 8W-80 CONNECTOR PIN-OUTWJ

CONNECTOR NAME/
NUMBERCOLOR LOCATION FIG.
Coil On Plug NO. 8 (4.7L) BK Right Side of Engine Near Fuel
Injector No.814, 15
Coil Rail (4.0L) BK Right Rear of Engine 10, 11
Compact Disc Changer BK Near Radio N/S
Compact Disc Changer BK Right Rear Quarter Panel 37
Controller Antilock Brake BK Left Front Engine Compartment 3, 4
Coolant Level Sensor LT GY Right Rear of Engine 5
Crankcase Heater (Diesel) BK Near T/O for G105 8
Crankshaft Position Sensor
(Diesel)BK Rear of Engine Near Transmission
Bell HousingN/S
Crankshaft Position Sensor
(Gas)BK Rear of Engine Near Transmission
Bell Housing10, 11, 14, 15, 17
Data Link Connector BK Under Lower Driver's Side of
Instrument Panel20, 21, 22
Diagnostic Junction Port BK At Steering Column 23
Driver Airbag Squib 1 BK In Steering Wheel N/S
Driver Airbag Squib 2 BK In Steering Wheel N/S
Driver Blend Door Motor/
Actuator (AZC)BK On HVAC Housing N/S
Driver Cylinder Lock Switch GY In Driver Door 24, 25
Driver Door Lock Motor/Ajar
SwitchBK In Driver Door 24, 25
Driver Door Module - C1 WT In Driver Door 24, 25
Driver Door Module - C2 BK In Driver Door N/S
Driver Door Module - C3 BK In Driver Door N/S
Driver Front Door Courtesy
LampBK In Driver Door N/S
Driver Front Power Window
MotorBK In Driver Door 24, 25
Driver Heated Seat Back
(Premium I/III)GN At Driver Seat N/S
Driver Heated Seat Cushion
(Premium I/III)BK At Driver Seat N/S
Driver Heated Seat Switch WT Center of Instrument Panel 19 20, 21
Driver Lumbar Motor
(Midline/Premium)BK At Driver Seat N/S
Driver Lumbar Switch
(Midline/Premium)WT At Driver Seat N/S
Driver Power Mirror BK At Driver Door N/S
Driver Power Seat Front Riser
MotorRD At Driver Seat N/S
Driver Power Seat Front Riser
Motor Sensor (Premium II/III)BK At Driver Seat N/S
Driver Power Seat Horizontal
MotorBK At Driver Seat N/S
8W - 91 - 4 8W-91 CONNECTOR/GROUND/SPLICE LOCATIONWJ
CONNECTOR/GROUND/SPLICE LOCATION (Continued)

CONNECTOR NAME/
NUMBERCOLOR LOCATION FIG.
Output Speed Sensor (4.0L) GY Left Side of Transmission 12
Output Speed Sensor (4.7L) BK Left Side of Transmission 16
Overhead Map/Courtesy Lamp WT At Overhead Console N/S
Oxygen Sensor 1/1 Upstream
(4.0L)GY Left Side of Engine at Exhaust 9, 12
Oxygen Sensor 1/1 Upstream
(4.7L)GY Left Side of Engine at Exhaust 17
Oxygen Sensor 1/2
Downstream (4.0L)BK Rear of Transmission 9, 12
Oxygen Sensor 1/2
Downstream (4.7L)BK Rear of Transmission 17
Oxygen Sensor 2/1 Upstream Rear of Transmission N/S
Oxygen Sensor 2/2
DownstreamRear of Transmission N/S
Park Brake Switch Center Console Area, Near Airbag
Control Module20, 21, 22
Park/Neutral Position Switch
(4.0L)BK Left Side of Transmission 12
Park/Neutral Position Switch
(Diesel)BK Left Side of Transmission N/S
Passenger Airbag YL Passenger Side of Instrument Panel 19, 20
Passenger Blend Door
Motor/Actuator (AZC)BK Passenger Side of Instrument Panel N/S
Passenger Door Lock
Motor/Ajar SwitchBK In Passenger Door 26, 27
Passenger Door Module - C1 WT In Passenger Door 26, 27
Passenger Door Module - C2 BK In Passenger Door N/S
Passenger Front Door
Courtesy LampBK In Passenger Door N/S
Passenger Front Power
Window MotorBK In Passenger Door 26, 27
Passenger Heated Seat Back
(Premium I/III)GN At Passenger Seat N/S
Passenger Heated Seat
Cushion (Premium I/III)BK At Passenger Seat N/S
Passenger Heated Seat Switch BK Center of Instrument Panel 19, 20, 21
Passenger Lumbar Motor
(Midline/Premium)BK At Passenger Seat N/S
Passenger Lumbar Switch
(Midline/Premium)WT At Passenger Seat N/S
Passenger Power Mirror BK In Passenger Door N/S
Passenger Power Seat Front
Riser MotorRD At Passenger Seat N/S
Passenger Power Seat
Horizontal MotorRD At Passenger Seat N/S
8W - 91 - 8 8W-91 CONNECTOR/GROUND/SPLICE LOCATIONWJ
CONNECTOR/GROUND/SPLICE LOCATION (Continued)

SPLICE
NUMBERLOCATION FIG.
S147 (Diesel) In T/O for Controller Anti-Lock Brake 4
S151 In Headlamp Assembly N/S
S152 In Headlamp Assembly N/S
S153 In Headlamp Assembly N/S
S154 In Headlamp Assembly N/S
S155 In Headlamp Assembly N/S
S156 In Headlamp Assembly N/S
S158 4.7L RHD Near T/O for Fuel Injector No. 1 13
S159 In T/O for C101 N/S
S160 (4.7L High
Output)In T/O for C102 N/S
S162 (Diesel) In T/O for Wastegate Solenoid 4, 8
S163 Near T/O for Leak Detection Pump 3
S165 (Diesel) Near T/O for Left Front Wheel Speed Sensor 4
S168 Near T/O for Intake Air Temperature Sensor 7, 8
S169 Near T/O for Engine Control Module C1 7, 8
S170 Near T/O for Engine Control Module C2 7, 8
S171 Near T/O for C113 7
S172 Near T/O for C113 7
S174 Near Washer Fluid Level Switch Connector 3
S176 Near T/O for Intake Air Temperature Sensor 7
S200 In Trough Near T/O for Passenger Heated Seat Switch 21
S200 (RHD) Upper Center Instrument Panel 22
S201 In Trough Near T/O for Front Power Outlet 21
S201 (RHD) Near T/O for Power Connector 22
S202 In Trough Near T/O for Passenger Heated Seat Switch 21
S202 (RHD) Upper Center Instrument Panel 22
S203 In Trough Near T/O for Cigar Lighter 21
S203 (RHD) Lower Center Instrument Panel 22
S204 In Trough Near T/O for Power Connector 21
S204 (RHD) Right Center Instrument Panel 22
S205 Near T/O for Adjustable Pedal Switch 21
S205 (RHD) Upper Center Instrument Panel 22
S206 Near T/O for Adjustable Pedals Switch N/S
S206 (RHD) Upper Center Instrument Panel 22
S207 In Trough Near T/O for Radio Connectors 21
S207 (RHD) Upper Center Instrument Panel 22
S208 In Trough Near T/O for Radio Connectors 21
S208 (RHD) Upper Center Instrument Panel 22
S209 In Trough Near T/O for Left Courtesy Lamp 21
S209 (RHD) Lower Center Instrument Panel 22
S210 In Trough Near T/O for Left Courtesy Lamp 21
8W - 91 - 14 8W-91 CONNECTOR/GROUND/SPLICE LOCATIONWJ
CONNECTOR/GROUND/SPLICE LOCATION (Continued)

INSTRUMENT PANEL CENTER
BEZEL - LOWER
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE AIRBAG SYSTEM BEFORE ATTEMPT-
ING ANY STEERING WHEEL, STEERING COLUMN, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT TWO MIN-
UTES FOR THE AIRBAG SYSTEM CAPACITOR TO DIS-
CHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE TO
TAKE THE PROPER PRECAUTIONS COULD RESULT
IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSI-
BLE PERSONAL INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Using a trim stick or another suitable wide
flat-bladed tool, gently pry each of the four corners of
the center lower bezel away from the instrument
panel far enough to disengage the four snap clips
from their receptacles (Fig. 27).
(3) Pull the center lower bezel away from the
instrument panel far enough to access the instru-
ment panel wire harness connectors.
(4) Squeeze the mounting legs of the ash receiver
lamp hood and remove it from the rectangular hole
in the ash receiver flame shield.(5) If the vehicle is so equipped, disconnect the
instrument panel wire harness connectors for the two
heated seat switches from the switch connector
receptacles.
(6) Disconnect the instrument panel wire harness
connectors for the cigar lighter and accessory power
outlet from the lighter and outlet connector recepta-
cles.
(7) Remove the center lower bezel from the instru-
ment panel.
INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Position the center lower bezel to the instru-
ment panel.
(2) Reconnect the instrument panel wire harness
connectors for the cigar lighter and the accessory
power outlet to the lighter and outlet connector
receptacles.
(3) If the vehicle is so equipped, reconnect the
instrument panel wire harness connectors for the two
heated seat switches to the switch connector recepta-
cles.
(4) Squeeze the mounting legs of the ash receiver
lamp hood and install them into the rectangular hole
in the ash receiver flame shield.
(5) Align the two lower snap clips on the center
lower bezel with their receptacles in the instrument
panel top pad.
(6) Using hand pressure, press firmly and evenly
on the center lower bezel over each of the lower snap
clip locations until each of the snap clips is fully
engaged in its receptacle.
(7) Align the two upper snap clips on the center
lower bezel with their receptacles in the instrument
panel top pad.
(8) Using hand pressure, press firmly and evenly
on the center lower bezel over each of the upper snap
clip locations until each of the snap clips is fully
engaged in its receptacle.
(9) Reconnect the battery negative cable.
Fig. 27 Instrument Panel Center Lower Bezel
Remove/Install
1 - HEATER AND AIR CONDITIONER CONTROLS
2 - TRIM STICK
3 - CENTER LOWER BEZEL
WJINSTRUMENT PANEL SYSTEM 23 - 57

INSTALLATION
(1) Position seat on floor pan.
(2) If equipped, connect power seat wire harness
connector.
(3) Install rear bolts attaching seat to floor pan.
Tighten bolts to 40 N´m (30 ft. lbs.) torque.
(4) If equipped, install cover on seat track.
(5) Move seat to full rearward position.
(6) Install front bolts attaching seat to floor pan.
Tighten bolts to 40 N´m (30 ft. lbs.) torque.
FRONT SEAT BACK
REMOVAL
(1) Move seat to full rearward position.
(2) Remove inboard bolt attaching seat back frame
to seat cushion frame.
(3) Move seat to full forward position.
(4) Move seat back to full recline position.
(5) Remove screws attaching seat side shield to
seat frame.
(6) Disconnect wire harness connector from
recliner motor, if equipped.
(7) From the underside of the seat, disconnect the
wire harness connector for the power lumber and/or
heated seat, if equipped.
(8) Remove outboard bolts attaching recliner to
seat cushion frame.
(9) Route the power lumber and/or heated seat
harness through the seat cushion cover, if equipped.
(10) Separate seat back from seat cushion.
INSTALLATION
(1) Position seat back on seat cushion.
(2) Route the power lumber and heater harness
through the seat cushion cover, if equipped.
(3) Install recliner bolts attaching seat back frame
to seat cushion frame. Tighten bolts to 28 N´m (20 ft.
lbs.) torque.
(4) Install the inboard bolt attaching seat back
frame to seat cushion frame. Tighten bolt to 47N´m
(35 ft.lbs.).
(5) Connect wire harness connector to recliner
motor and/or heated seat, if equipped.
(6) From the underside of the seat, connect the
power lumber and/or heated seat wire harness con-
nector to the seat harness, if equipped.
(7) Install screws attaching seat side shield to seat
frame.
FRONT SEAT BACK COVER
REMOVAL
(1) Remove head restraint (Refer to 23 - BODY/
SEATS/FRONT HEADREST - REMOVAL).
(2) Using a trim stick, carefully pry head restraint
release button caps from the top of seat back.
(3) Remove seat back (Refer to 23 - BODY/SEATS/
FRONT SEAT BACK - REMOVAL).
(4) Disengage J-strap at base of seat back.
(5) Slide hand between the face of the seat back
pad and the cushion cover and carefully separate
hook and loop fastener (Fig. 5).
(6) Roll cover upward and disengage hog rings.
(7) Roll cover upward to top of seat back.
(8) Separate cover from seat back.
INSTALLATION
(1) Position cover inside-out at the top of seat
back.
(2) Roll cover downward.
(3) Engage hog rings.
(4) Align seat back cover with hook and loop fas-
teners and secure.
(5) Roll cover downward.
(6) Engage J-strap at base of seat back.
(7) Install seat back (Refer to 23 - BODY/SEATS/
FRONT SEAT BACK - INSTALLATION).
NOTE: The taller head restraint release button cap
is positioned on the left hand side and the head
restraint button cap with the hidden button is posi-
tioned on the right hand side.
Fig. 5 Seat Back Cover
1 - SEAT BACK COVER
2 - HOOK AND LOOP FASTENER
3 - SEAT BACK PAD
WJSEATS 23 - 85
FRONT SEAT (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)