Power train JEEP GRAND CHEROKEE 2002 WJ / 2.G Workshop Manual

POSITION SENSOR
DESCRIPTION
The transfer case position sensor (Fig. 95) is an
electronic device whose output can be interpreted to
indicate the transfer case's current operating mode.
The sensor consists of a five position, resistive multi-
plexed circuit which returns a specific resistance
value to the Powertrain Control Module (PCM) for
each transfer case operating mode. The sensor is
located on the top of the transfer case, just left of the
transfer case centerline and rides against the sector
plate roostercomb. The PCM supplies 5VDC (+/-
0.5V) to the sensor and monitors the return voltage
to determine the sector plate, and therefore the
transfer case, position.
OPERATION
During normal vehicle operation, the Powertrain
Control Module (PCM) monitors the transfer case
position sensor return voltage to determine the oper-
ating mode of the transfer case. Refer to the Operat-
ing Mode Versus Resistance table for the correct
resistance for each position (Fig. 96).
OPERATING MODE VERSUS RESISTANCE
SENSOR POSITION OPERATING MODE SENSOR RESISTANCE (ohms)
1 2WD 1124-1243
2 4WD PART TIME 650-719
3 4WD FULL TIME 389-431
4 NEUTRAL 199-221
5 4WD LOW 57-64
Fig. 96 Position Sensor Linear Movement
1 - POSITION 1 - 10mm  0.5mm
2 - POSITION 2 - 12mm  0.5mm
3 - POSITION 3 - 14mm  0.5mm
4 - POSITION 4 - 16mm  0.5mm
5 - POSITION 5 - 18mm  0.5mm
6 - POSITION 6 - 20mm 0.5mm - FULL EXTENSION
Fig. 95 Transfer Case Position Sensor and
Connector
1 - TRANSFER CASE POSITION SENSOR CONNECTOR
2 - TRANSFER CASE POSITION SENSOR
3 - TRANSFER CASE
4 - OUTPUT SPEED SENSOR CONNECTOR
WJTRANSFER CASE - NV242 21 - 311

FRONT HEADREST SLEEVE
REMOVAL
(1) Remove head restraint (Refer to 23 - BODY/
SEATS/FRONT HEADREST - REMOVAL).
(2) Remove seat back cover (Refer to 23 - BODY/
SEATS/FRONT SEAT BACK COVER - REMOVAL).
(3) Remove hog rings attaching cushion pad to
seat back frame (Fig. 2).
(4) Remove cushion pad from seat back frame.
(5) Rotate head restraint sleeve 1/4 turn counter-
clockwise to release retaining tab.
(6) Pull sleeve from seat back frame (Fig. 3).
INSTALLATION
(1) Position sleeve in seat back frame.
(2) Rotate head restraint sleeve 1/4 turn clockwise
to engage retaining tab.
(3) Install cushion pad onto seat back frame.
(4) Install hog rings attaching cushion pad to seat
back frame.
(5)
Install seat back cover (Refer to 23 - BODY/
SEATS/FRONT SEAT BACK COVER - INSTALLATION).
(6) Install head restraint (Refer to 23 - BODY/
SEATS/FRONT HEADREST - INSTALLATION).
FRONT SEAT
REMOVAL
(1) Move seat to full rearward position.(2) Remove front bolts attaching seat to floor pan
(Fig. 4).
(3) Move seat to full forward position.
(4) Using a trim stick, pry cover from seat track
(power seat only).
(5) Remove rear bolts attaching seat to floor pan.
(6) If equipped, disconnect power seat wire har-
ness connector.
(7) Remove seat from vehicle.
Fig. 2 Cushion Pad
1 - HOG RING
2 - SEAT BACK CUSHION PAD
Fig. 3 Head Restraint Sleeve
1 - HEAD RESTRAINT SLEEVE
2 - SEAT BACK FRAME
3 - RETAINING TAB
Fig. 4 Front Bucket Seat
1 - POWER BUCKET SEAT
2 - FLOOR PAN
3 - SEAT TRACK COVER
23 - 84 SEATSWJ

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)

(8) Position head restraint release button caps on
head restraint sleeves and press to secure.
(9) Install head restraint (Refer to 23 - BODY/
SEATS/FRONT HEADREST - INSTALLATION).
FRONT SEAT CUSHION/COVER
REMOVAL
(1) Remove seat from vehicle (Refer to 23 - BODY/
SEATS/FRONT SEAT - REMOVAL).
(2) Remove seat back (Refer to 23 - BODY/SEATS/
FRONT SEAT BACK - REMOVAL).
(3) Disengage J-straps attaching cushion cover to
seat cushion frame.
(4) Disengage hog rings attaching cushion cover to
cushion frame at rear of seat along bottom of cushion
cover (Fig. 6).
(5) Roll up edges of cover and route seat function
switches through access hole on outboard side of seat
cushion, if equipped.
(6) Disengage seat cushion heater element connec-
tor, if equipped.
(7) Disengage hog rings attaching cover to cushion
along cover insert.
(8) Separate seat cushion cover from seat cushion.
INSTALLATION
(1) Position seat cover on cushion.
(2) Engage hog rings attaching cushion cover to
cushion along insert.
(3) Engage seat cushion heater element connector,
if equipped.
(4) Route seat function switches through access
hole on outboard side of seat cushion, if equipped.(5) Engage J-straps attaching cushion cover to seat
cushion frame.
(6) Engage hog rings attaching cushion cover to
cushion frame.
(7) Install seat back (Refer to 23 - BODY/SEATS/
FRONT SEAT BACK - INSTALLATION).
(8) Install seat (Refer to 23 - BODY/SEATS/
FRONT SEAT - INSTALLATION).
FRONT SEAT SIDE SHIELD
REMOVAL
(1) Remove screws attaching side shield to seat
frame.
(2) Disconnect wire harness connectors from power
seat and power lumbar switches, if equipped.
(3) Separate side shield from seat.
INSTALLATION
(1) Position side shield on seat.
(2) Connect wire harness connectors to power seat
and power lumbar switches, if equipped.
(3) Install screws attaching side shield to seat
frame.
SEAT TRACK & RECLINER
ASSEMBLY
REMOVAL
(1) Remove seat back (Refer to 23 - BODY/SEATS/
FRONT SEAT BACK - REMOVAL).
(2) Disengage J-strap at base of seat back.
(3) Roll seat back cover upward to access bolts
attaching recliner to seat back frame.
(4) Remove bolts attaching recliner to seat back
frame.
(5) Separate recliner from seat back.
INSTALLATION
(1) Position recliner on seat back.
(2) Install bolts attaching recliner to seat back
frame. Tighten bolts to 28 N´m (20 ft. lbs.) torque.
(3) Roll seat back cover downward.
(4) Engage J-strap at base of seat back.
(5) Install seat back (Refer to 23 - BODY/SEATS/
FRONT SEAT BACK - INSTALLATION).Fig. 6 Seat Cushion Cover
1 - HOG RING
2 - CUSHION COVER
23 - 86 SEATSWJ
FRONT SEAT BACK COVER (Continued)

(9) Compare the compressor discharge pressure to
the Performance Temperature and Pressure chart. If
the compressor discharge pressure is high, see the
Pressure Diagnosis chart.
Pressure Diagnosis
Condition Possible Causes Correction
Rapid compressor clutch
cycling (ten or more cycles
per minute).1. Low refrigerant system
charge.1. See Plumbing/Diagnosis and Testing -
Refrigerant System Leaks in this group. Test the
refrigerant system for leaks. Repair, evacuate and
charge the refrigerant system, if required.
Equal pressures, but the
compressor clutch does not
engage.1. No refrigerant in the
refrigerant system.1. See Plumbing/Diagnosis and Testing -
Refrigerant System Leaks in this group. Test the
refrigerant system for leaks. Repair, evacuate and
charge the refrigerant system, if required.
2. Faulty fuse. 2. Check the fuses in the Power Distribution
Center and the junction block. Repair the shorted
circuit or component and replace the fuses, if
required.
3. Faulty a/c compressor
clutch coil.3. See A/C Compressor/Diagnosis and Testing -
Compressor Clutch Coil in this group. Test the
compressor clutch coil and replace, if required.
4. Faulty compressor clutch
relay.4. See A/C Compressor Clutch Relay/Diagnosis
and Testing - Compressor Clutch Relay in this
group. Test the compressor clutch relay and relay
circuits. Repair the circuits or replace the relay, if
required.
6. Faulty a/c high pressure
transducer.6. See A/C High Pressure Transducer/Diagnosis
and Testing in this group. Test the a/c high
pressure transducer and replace, if required.
7. Faulty Fin Probe. 7. Check for open circuit.
8. Faulty Powertrain Control
Module (PCM).8. Refer to the proper Diagnostic Procedures
manual for testing of the PCM. Test the PCM and
replace, if required.
Normal pressures, but A/C
Performance Test air
temperatures at center panel
outlet are too high.1. Excessive refrigerant oil in
system.1. See Refrigerant Oil/Standard Procedure -
Refrigerant Oil Level in this group. Recover the
refrigerant from the refrigerant system and
inspect the refrigerant oil content. Restore the
refrigerant oil to the proper level, if required.
2. Blend door inoperative or
sealing improperly.2. See Blend Door in this group. Inspect the
blend door for proper operation and sealing and
correct, if required.
3. Blend door actuator faulty
or inoperative.3. Perform blend door actuator diagnosis, replace
if faulty.
24 - 4 HEATING & AIR CONDITIONINGWJ
HEATING & AIR CONDITIONING (Continued)

A/C COMPRESSOR CLUTCH
DESCRIPTION
The compressor clutch assembly consists of a sta-
tionary electromagnetic coil, a hub bearing and pul-
ley assembly, and a clutch plate (Fig. 4). The
electromagnetic coil unit and the hub bearing and
pulley assembly are each retained on the nose of the
compressor front housing with snap rings. The clutch
plate is keyed to the compressor shaft and secured
with a bolt.
OPERATION
The compressor clutch components provide the
means to engage and disengage the compressor from
the engine serpentine accessory drive belt. When the
clutch coil is energized, it magnetically draws the
clutch into contact with the pulley and drives the
compressor shaft. When the coil is not energized, the
pulley freewheels on the clutch hub bearing, which is
part of the pulley. The compressor clutch and coil are
the only serviced parts on the compressor.
The compressor clutch engagement is controlled by
several components: the a/c switch on the a/c heater
control panel, the Automatic Zone Control (AZC) con-
trol module (if the vehicle is so equipped), the evap-
orator probe, the a/c high pressure transducer, the
a/c compressor clutch relay, the body control module
(BCM) and the Powertrain Control Module (PCM).
The PCM may delay compressor clutch engagement
for up to thirty seconds. Refer to Electronic Control
Modules for more information on the PCM controls.
DIAGNOSIS AND TESTING - COMPRESSOR
CLUTCH COIL
For circuit descriptions and diagrams, refer to the
appropriate wiring diagrams. The battery must be
fully-charged before performing the following tests.
Refer to Battery for more information.
(1) Connect an ammeter (0 to 10 ampere scale) in
series with the clutch coil terminal. Use a voltmeter
(0 to 20 volt scale) with clip-type leads for measuring
the voltage across the battery and the compressor
clutch coil.
(2) With the a/c heater mode control switch in any
a/c mode, the a/c heater control a/c switch in the ON
position, and the blower motor switch in the lowest
speed position, start the engine and run it at normal
idle.
(3) The compressor clutch coil voltage should read
within 0.2 volts of the battery voltage. If there is
voltage at the clutch coil, but the reading is not
within 0.2 volts of the battery voltage, test the clutch
coil feed circuit for excessive voltage drop and repair
as required. If there is no voltage reading at the
clutch coil, use a DRBIIItscan tool and the appro-
priate diagnostic information for testing of the com-
pressor clutch circuit. The following components
must be checked and repaired as required before you
can complete testing of the clutch coil:
²Fuses in the junction block and the Power Dis-
tribution Center (PDC)
²A/C heater mode control switch
²A/C compressor clutch relay
²A/C high pressure transducer
²A/C evaporator probe
²Powertrain Control Module (PCM)
²Body Control Module (BCM)
(4) The compressor clutch coil is acceptable if the
current draw measured at the clutch coil is 2.0 to 3.9
amperes with the electrical system voltage at 11.5 to
12.5 volts. This should only be checked with the work
area temperature at 21É C (70É F). If system voltage
is more than 12.5 volts, add electrical loads by turn-
ing on electrical accessories until the system voltage
drops below 12.5 volts.
(a) If the clutch coil current reading is four
amperes or more, the coil is shorted and should be
replaced.
(b) If the clutch coil current reading is zero, the
coil is open and should be replaced.
Fig. 4 COMPRESSOR CLUTCH - TYPICAL
1 - CLUTCH PLATE
2 - SHAFT KEY
3 - PULLEY
4 - COIL
5 - CLUTCH SHIMS
6 - SNAP RING
7 - SNAP RING
WJCONTROLS 24 - 13

gap should be between 0.35 to 0.65 millimeter (0.014
to 0.026 inch). If the proper air gap is not obtained,
add or subtract shims as needed until the desired air
gap is obtained.
(9) Install the compressor shaft bolt. Tighten the
bolt to 13 N´m (115 in. lbs.).
NOTE: The shims may compress after tightening
the shaft bolt. Check the air gap in four or more
places to verify the air gap is still correct. Spin the
pulley before performing a final check of the air
gap.
(10) To complete the installation, (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING/A/C
COMPRESSOR - INSTALLATION)
A/C COMPRESSOR CLUTCH
RELAY
DESCRIPTION
The compressor clutch relay is a International
Standards Organization (ISO) micro-relay. The termi-
nal designations and functions are the same as a con-
ventional ISO relay. However, the micro-relay
terminal orientation (footprint) is different, the cur-
rent capacity is lower, and the relay case dimensions
are smaller than those of the conventional ISO relay.
OPERATION
The compressor clutch relay is a electromechanical
device that switches battery current to the compres-
sor clutch coil when the Powertrain Control Module
(PCM) grounds the coil side of the relay. The PCM
responds to inputs from the a/c compressor switch on
the a/c heater control panel, the Automatic Zone Con-
trol (AZC) control module (if the vehicle is so
equipped), the a/c fin probe, and the a/c high pres-
sure transducer. (Refer to 24 - HEATING & AIR
CONDITIONING/CONTROLS/A/C COMPRESSOR
CLUTCH RELAY - DIAGNOSIS AND TESTING)
The compressor clutch relay is located in the Power
Distribution Center (PDC) in the engine compart-
ment. Refer to the PDC label for relay identification
and location.
The compressor clutch relay cannot be repaired
and, if faulty or damaged, it must be replaced.
DIAGNOSIS AND TESTING - A/C COMPRESSOR
CLUTCH RELAY
For circuit descriptions and diagrams, refer to the
appropriate wiring information.
The compressor clutch relay (Fig. 10) is located in
the Power Distribution Center (PDC). Refer to the
PDC label for relay identification and location.Remove the relay from the PDC to perform the fol-
lowing tests:
(1) A relay in the de-energized position should
have continuity between terminals 87A and 30, and
no continuity between terminals 87 and 30. If OK, go
to Step 2. If not OK, replace the faulty relay.
(2) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 75   5 ohms. If OK, go to Step
3. If not OK, replace the faulty relay.
(3) Connect a battery to terminals 85 and 86.
There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, see the Relay Circuit Test procedure
in this group. If not OK, replace the faulty relay.
RELAY CIRCUIT TEST
For circuit descriptions and diagrams, refer to the
appropriate wiring information..
(1) The relay common feed terminal cavity (30) is
connected to fused battery feed. There should be bat-
tery voltage at the cavity for relay terminal 30 at all
times. If OK, go to Step 2. If not OK, repair the open
circuit to the fuse in the PDC as required.
(2) The relay normally closed terminal (87A) is not
used in this application. Go to Step 3.
(3) The relay normally open terminal cavity (87) is
connected to the compressor clutch coil. There should
be continuity between this cavity and the A/C com-
pressor clutch relay output circuit cavity of the com-
pressor clutch coil wire harness connector. If OK, go
to Step 4. If not OK, repair the open circuit as
required.
(4) The relay coil battery terminal (86) is con-
nected to the fused ignition switch output (run/start)
circuit. There should be battery voltage at the cavity
for relay terminal 86 with the ignition switch in the
On position. If OK, go to Step 5. If not OK, repair the
Fig. 10 A/C COMPRESSOR CLUTCH RELAY
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
24 - 16 CONTROLSWJ
A/C COMPRESSOR CLUTCH (Continued)

open circuit to the fuse in the junction block as
required.
(5) The coil ground terminal cavity (85) is switched
to ground through the Powertrain Control Module
(PCM). There should be continuity between this cav-
ity and the A/C compressor clutch relay control cir-
cuit cavity of the PCM wire harness connector C
(gray) at all times. If not OK, repair the open circuit
as required.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the cover from the Power Distribution
Center (PDC) (Fig. 11).
(3) Refer to the label on the PDC for compressor
clutch relay identification and location.
(4) Unplug the compressor clutch relay from the
PDC.
INSTALLATION
(1) Install the compressor clutch relay by aligning
the relay terminals with the cavities in the PDC and
pushing the relay firmly into place.
(2) Install the PDC cover.
(3) Connect the battery negative cable.
(4) Test the relay operation.
A/C HEATER CONTROL
DESCRIPTION
The manual temperature control HVAC system
uses a combination of electrical, and vacuum con-trols. The Automatic Zone Control (AZC) HVAC sys-
tem uses only electrical controls. These controls
provide the vehicle operator with a number of setting
options to help control the climate and comfort
within the vehicle. Refer to the owner's manual in
the vehicle glove box for more information on the
suggested operation and use of these controls.
Both a/c heater control panels are located on the
instrument panel inboard of the steering column and
below the radio (Fig. 12). Both control panels contain
rotary-type temperature control knob(s), a rotary-
type mode control switch knob, a rotary-type blower
motor speed switch knob and an air conditioning
compressor push button switch. The rear window
defogger push button switch is also located on a/c
heater control panel. The AZC control panel also fea-
tures a recirculation push button switch and a vac-
uum fluorescent display area.
OPERATION
The AZC control module uses infrared sensing
technology to control occupant comfort levels, not the
actual passenger compartment air temperature. Dual
infrared sensors mounted in the face of the control
unit independently measure the surface temperature
to maintain customer-perceived comfort temperature
under changing conditions. Dual Zone temperature
control provides wide side-to-side variation in comfort
temperature to exceed the needs of either front seat
occupant. This sensing system replaces interior air
temperature and solar sensors used to approximate
direct sensing control through complex control pro-
grams.
Fig. 11 POWER DISTRIBUTION CENTER (PDC)
1 - TRANSMISSION CONTROL MODULE (TCM)
2 - NEGATIVE CABLE
3 - POSITIVE CABLE
4 - POWER DISTRIBUTION CENTER (PDC)
Fig. 12 A/C HEATER CONTROL PANELS
WJCONTROLS 24 - 17
A/C COMPRESSOR CLUTCH RELAY (Continued)

INSTALLATION
(1) Plug the wire harness and/or vacuum harness
connectors into the back of the a/c heater control.
(2) Position the a/c heater control in the instru-
ment panel and secure it with 4 screws. Tighten the
screws to 2.2 N´m (20 in. lbs.).
(3) Reinstall the center upper, and center lower
bezels onto the instrument panel. Refer to Instru-
ment Panel System for the procedures.
(4) Connect the battery negative cable.
A/C PRESSURE TRANSDUCER
DESCRIPTION
The A/C pressure transducer is installed on a fit-
ting located on the refrigerant discharge line near
the condenser. An internally threaded hex fitting on
the transducer connects it to the externally threaded
Schrader-type fitting on the discharge line. A rubber
O-ring seals the connection between the transducer
and the discharge line fitting. Three terminals within
a molded plastic connector receptacle on the top of
the transducer connect it to the vehicle electrical sys-
tem through a take out and connector of the head-
lamp and dash wire harness.
The A/C pressure transducer cannot be adjusted or
repaired and if faulty or damaged, it must be
replaced.
OPERATION
The A/C pressure transducer monitors the pres-
sures in the high side of the refrigerant system
through its connection to a fitting on the discharge
line. The transducer will change its internal resis-
tance in response to the pressures it monitors. The
Powertrain Control Module (PCM) provides a five
volt reference signal and a sensor ground to the
transducer, then monitors the output voltage of the
transducer on a sensor return circuit to determine
refrigerant pressure. The PCM is preporgrammed to
respond to this and other sensor inputs by controlling
the operation of the air conditioning compressor
clutch and the radiator cooling fan to help optimize
air conditioning system performance and to protect
the system components from damage. The A/C pres-
sure transducer input to the PCM will also prevent
the air conditioning compressor clutch from engaging
when the ambient temperatures are below about
0.556É C (33É F) due to the pressure/temperature
relationship of the refrigerant. The Schrader-type
valve in the liquid line fitting permits the A/C pres-
sure transducer to be removed or installed without
distrubing the refrigerant in the system. The A/C
pressure transducer is diagnosed using the DRBIIIt
scan tool. Refer to the appropriate diagnostic infor-
mation.
Fig. 13 A/C HEATER CONTROL REMOVE/INSTALL
1 - MOUNTING SCREW TABS
Fig. 14 A/C HEATER CONTROL CONNECTIONS
1 - MODE SWITCH
2 - ELECTRICAL CONNECTIONS
3 - VACUUM HARNESS
WJCONTROLS 24 - 25
A/C HEATER CONTROL (Continued)

DIAGNOSIS AND TESTING - A/C PRESSURE
TRANSDUCER
The A/C pressure transducer is tested using a
DRBIIItscan tool. Refer to the appropriate diagnos-
tic information. Before testing the A/C pressure
transducer, be certain that the transducer wire har-
ness connection is clean of corrosion and properly
connected. For the air conditioning system to operate,
an A/C pressure transducer voltage reading between0.7 and 4.56 volts is required. Voltage outside this
range indicate a low or high refrigerant system pres-
sure condition to the Powertrain Control Module
(PCM). The PCM is programmed to respond to a low
or high refrigerant system pressure by suppressing
operation of the compressor. Refer to the A/C Pres-
sure Transducer Voltage table for the possible condi-
tion indicated by the transducer voltage readings.
A/C PRESSURE TRANSDUCER VOLTAGE
VOLTAGE POSSIBLE INDICATION
0.0 1. NO SENSOR SUPPLY VOLTAGE FROM PCM.
2. SHORTED SENSOR CIRCUIT.
3. FAULTY TRANSDUCER
0.150 TO 0.450 1. AMBIENT TEMPERATURE BELOW 10É c (50É F).
2. LOW REFRIGERANT SYSTEM PRESSURE.
0.451 TO 4.519 1. NORMAL REFRIGERANT SYSTEM PRESSURE.
4.520 TO 4.850 1. HIGH REFRIGERANT SYSTEM PRESSURE.
5.0 1. OPEN SENSOR CIRCUIT.
2. FAULTY TRANSDUCER.
REMOVAL
WARNING: Transducer can be removed without
recoverying the system, but some loss of refriger-
ant can be expected(Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING - WARNING) and (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING -
CAUTION).
(1) Disconnect and isolate the battery negative
cable.
(2) Disconnect the headlamp and dash wire har-
ness connector for the A/C pressure transducer from
the transducer connector receptacle.
(3) Using an open end wrench, unscrew the A/C
pressure transducer from the fitting on the discharge
line.
(4) Remove the seal from the A/C pressure trans-
ducer fitting and discard.
INSTALLATION
(1) Lubricate a new O-ring seal with clean refrig-
erant oil and install it on the A/C pressure trans-
ducer fitting.
(2) Using an open end wrench, install and tighten
the A/C pressure transducer onto the fitting on the
discharge line.
(3) Reconnect the headlamp and dash wire harness
connector for the A/C pressure transducer to the
transducer connector receptacle.(4) Reconnect the battery negative cable.
BLOWER MOTOR
CONTROLLER
DESCRIPTION
Models equipped with the optional Automatic Zone
Control (AZC) system have a blower motor controller.
The controller allows the selection of almost infi-
nitely variable blower motor speeds. The controller is
mounted to the HVAC housing, under the instrument
panel and just inboard of the blower motor, in the
same location used for the blower motor resistor on
manual temperature control systems. It can be
accessed without removing any other components.
OPERATION
The blower motor controller output to the blower
motor can be adjusted by the blower motor speed
switch knob on the AZC A/C Heater control panel, or
it can be adjusted automatically by the logic circuitry
and programming of the AZC control module. In
either case, the AZC control module sends the correct
pulse width modulated signal to the blower motor
controller to obtain the selected or programmed
blower motor speed.
The blower motor controller cannot be repaired
and, if faulty or damaged, it must be replaced.
24 - 26 CONTROLSWJ
A/C PRESSURE TRANSDUCER (Continued)