Powertrain control JEEP LIBERTY 2002 KJ / 1.G Owners Manual

INSTALLATION
2.4L
The Manifold Absolute Pressure (MAP) sensor is
mounted into the rear of the intake manifold. An
o-ring is used to seal the sensor to the intake mani-
fold (Fig. 19).
(1) Clean MAP sensor mounting hole at intake
manifold.
(2) Check MAP sensor o-ring seal for cuts or tears.
(3) Position sensor into manifold.
(4) Install MAP sensor mounting screws. Tighten
screw to 3 N´m (25 in. lbs.) torque.
(5) Connect electrical connector.
3.7L
The Manifold Absolute Pressure (MAP) sensor is
mounted into the front of the intake manifold (Fig.
18). An o-ring is used to seal the sensor to the intake
manifold (Fig. 19).
(1) Clean MAP sensor mounting hole at intake
manifold.
(2) Check MAP sensor o-ring seal for cuts or tears.
(3) Position sensor into manifold.
(4) Install MAP sensor mounting bolts (screws).
Tighten screws to 3 N´m (25 in. lbs.) torque.
(5) Connect electrical connector.
OXYGEN SENSOR
DESCRIPTION
The Oxygen Sensors (O2S) are attached to, and
protrude into the vehicle exhaust system. Depending
on the engine or emission package, the vehicle may
use a total of either 2 or 4 sensors.
2.4L Engine:Two sensors are used: upstream
(referred to as 1/1) and downstream (referred to as
1/2). With this emission package, the upstream sen-
sor (1/1) is located just before the main catalytic con-
vertor. The downstream sensor (1/2) is located just
after the main catalytic convertor.
3.7L V-6 Engine:On this emissions package, 4
sensors are used: 2 upstream (referred to as 1/1 and
2/1) and 2 downstream (referred to as 1/2 and 2/2).
With this emission package, the right upstream sen-
sor (2/1) is located in the right exhaust downpipe just
before the mini-catalytic convertor. The left upstream
sensor (1/1) is located in the left exhaust downpipe
just before the mini-catalytic convertor. The right
downstream sensor (2/2) is located in the right
exhaust downpipe just after the mini-catalytic con-
vertor, and before the main catalytic convertor. The
left downstream sensor (1/2) is located in the left
exhaust downpipe just after the mini-catalytic con-
vertor, and before the main catalytic convertor.
OPERATION
An O2 sensor is a galvanic battery that provides
the PCM with a voltage signal (0-1 volt) inversely
proportional to the amount of oxygen in the exhaust.
In other words, if the oxygen content is low, the volt-
age output is high; if the oxygen content is high the
output voltage is low. The PCM uses this information
to adjust injector pulse-width to achieve the
14.7±to±1 air/fuel ratio necessary for proper engine
operation and to control emissions.
The O2 sensor must have a source of oxygen from
outside of the exhaust stream for comparison. Cur-
rent O2 sensors receive their fresh oxygen (outside
air) supply through the O2 sensor case housing.
Four wires (circuits) are used on each O2 sensor: a
12±volt feed circuit for the sensor heating element; a
ground circuit for the heater element; a low-noise
sensor return circuit to the PCM, and an input cir-
cuit from the sensor back to the PCM to detect sen-
sor operation.
Oxygen Sensor Heater Relay - 3.7L Engine:On
the 3.7L engine, 4 heated oxygen sensors are used. A
separate oxygen sensor relay is used to supply volt-
age to the sensors heating elements for only the 1/2
and 2/2 downstream sensors. Voltage for the other 2
sensor heating elements is supplied directly from the
Powertrain Control Module (PCM) through a Pulse
Width Module (PWM) method.
Pulse Width Module (PWM):Voltage to the O2
sensor heating elements is supplied directly from the
Powertrain Control Module (PCM) through two sepa-
rate Pulse Width Module (PWM) low side drivers.
PWM is used on both the upstream and downstream
O2 sensors on the 2.4L engine, and only on the 2
upstream sensors (1/1 and 2/1) on the 3.7L engine.
The main objective for a PWM driver is to avoid over-
heating of the O2 sensor heater element. With
exhaust temperatures increasing with time and
engine speed, it's not required to have a full-voltage
duty-cycle on the O2 heater elements.
To avoid the large simultaneous current surge
needed to operate all 4 sensors, power is delayed to
the 2 downstream heater elements by the PCM for
approximately 2 seconds.
Oxygen Sensor Heater Elements:
The O2 sensor uses a Positive Thermal Co-efficient
(PTC) heater element. As temperature increases,
resistance increases. At ambient temperatures
around 70ÉF, the resistance of the heating element is
approximately 4.5 ohms. As the sensor's temperature
increases, resistance in the heater element increases.
This allows the heater to maintain the optimum
operating temperature of approximately 930É-1100ÉF
(500É-600É C). Although the sensors operate the
same, there are physical differences, due to the envi-
14 - 40 FUEL INJECTIONKJ
MAP SENSOR (Continued)

WARNING: THE EXHAUST MANIFOLD, EXHAUST
PIPES AND CATALYTIC CONVERTER BECOME
VERY HOT DURING ENGINE OPERATION. ALLOW
ENGINE TO COOL BEFORE REMOVING OXYGEN
SENSOR.
(1) Raise and support vehicle.
(2) Disconnect wire connector from O2S sensor.
CAUTION: When disconnecting sensor electrical
connector, do not pull directly on wire going into
sensor.
(3) Remove O2S sensor with an oxygen sensor
removal and installation tool.
(4) Clean threads in exhaust pipe using appropri-
ate tap.
INSTALLATION
Threads of new oxygen sensors are factory coated
with anti-seize compound to aid in removal.DO
NOT add any additional anti-seize compound to
threads of a new oxygen sensor.
(1) Install O2S sensor. Tighten to 30 N´m (22 ft.
lbs.) torque.
(2) Connect O2S sensor wire connector.
(3) Lower vehicle.
THROTTLE BODY
DESCRIPTION
The throttle body is located on the intake manifold.
Fuel does not enter the intake manifold through the
throttle body. Fuel is sprayed into the manifold by
the fuel injectors.
OPERATION
Filtered air from the air cleaner enters the intake
manifold through the throttle body. The throttle body
contains an air control passage controlled by an Idle
Air Control (IAC) motor. The air control passage is
used to supply air for idle conditions. A throttle valve
(plate) is used to supply air for above idle conditions.
Certain sensors are attached to the throttle body.
The accelerator pedal cable, speed control cable and
transmission control cable (when equipped) are con-
nected to the throttle body linkage arm.
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate.Never attempt to adjust the engine idle
speed using this screw.All idle speed functions are
controlled by the PCM.
REMOVAL
2.4L
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate.Never attempt to adjust the engine idle
speed using this screw.All idle speed functions are
controlled by the Powertrain Control Module (PCM).
(1) Remove air cleaner tube at throttle body.
(2) Disconnect throttle body electrical connectors
at IAC motor and TPS.
(3) Remove all control cables from throttle body
(lever) arm. Refer to the Accelerator Pedal and Throt-
tle Cable section for removal/installation procedures.
(4) Disconnect necessary vacuum lines at throttle
body.
(5) Remove 3 throttle body mounting bolts (Fig.
23).
(6) Remove throttle body from intake manifold.
(7) Check condition of old throttle body-to-intake
manifold o-ring.
3.7L
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate.Never attempt to adjust the engine idle
speed using this screw.All idle speed functions are
controlled by the Powertrain Control Module (PCM).
(1) Remove air cleaner tube at throttle body.
(2) Disconnect throttle body electrical connectors
at IAC motor and TPS.
Fig. 23 THROTTLE BODY MOUNTING BOLTS - 2.4L
1 - THROTTLE BODY
2 - IGNITION COIL
3 - MOUNTING BOLTS (3)
KJFUEL INJECTION 14 - 43
OXYGEN SENSOR (Continued)

THROTTLE POSITION SENSOR
DESCRIPTION
The 3±wire Throttle Position Sensor (TPS) is
mounted on the throttle body and is connected to the
throttle blade shaft.
OPERATION
The 3±wire TPS provides the Powertrain Control
Module (PCM) with an input signal (voltage) that
represents the throttle blade position of the throttle
body. The sensor is connected to the throttle blade
shaft. As the position of the throttle blade changes,
the output voltage of the TPS changes.
The PCM supplies approximately 5 volts to the
TPS. The TPS output voltage (input signal to the
PCM) represents the throttle blade position. The
PCM receives an input signal voltage from the TPS.
This will vary in an approximate range of from .26
volts at minimum throttle opening (idle), to 4.49 volts
at wide open throttle. Along with inputs from other
sensors, the PCM uses the TPS input to determine
current engine operating conditions. In response to
engine operating conditions, the PCM will adjust fuel
injector pulse width and ignition timing.
The PCM needs to identify the actions and position
of the throttle blade at all times. This information is
needed to assist in performing the following calcula-
tions:
²Ignition timing advance
²Fuel injection pulse-width
²Idle (learned value or minimum TPS)
²Off-idle (0.06 volt)
²Wide Open Throttle (WOT) open loop (2.608
volts above learned idle voltage)
²Deceleration fuel lean out
²Fuel cutoff during cranking at WOT (2.608 volts
above learned idle voltage)
²A/C WOT cutoff (certain automatic transmis-
sions only)
REMOVAL
2.4L
The Throttle Position Sensor (TPS) is mounted to
the throttle body (Fig. 31).
(1) Disconnect TPS electrical connector.
(2) Remove 2 TPS mounting screws.
(3) Remove TPS.
Fig. 31 TPS/IAC MOTOR - 2.4L
1 - THROTTLE POSITION SENSOR (TPS)
2 - MOUNTING SCREWS
3 - IDLE AIR CONTROL MOTOR (IAC)
4 - MOUNTING SCREWS
KJFUEL INJECTION 14 - 47

(6) Install the serpentine belt (Refer to 7 - COOL-
ING/ACCESSORY DRIVE/DRIVE BELTS - INSTAL-
LATION).
(7) Install the fan shroud.
(8) Install the fan (Refer to 7 - COOLING/EN-
GINE/RADIATOR FAN - INSTALLATION).
(9) Install the radiator crossmember (Refer to 23 -
BODY/EXTERIOR/RADIATOR CROSSMEMBER -
INSTALLATION).
(10) Refill the power steering fluid (Refer to 19 -
STEERING/PUMP - STANDARD PROCEDURE).
INSTALLATION - RETURN HOSE (GEAR TO THE
COOLER)
(1) Install the return hose to the vehicle. (Fig. 7)
(2) Install the return hose mounting bracket bolts
to the front cradle.
(3) Install the return hose at the cooler.
(4) Install the return hose at the gear 28 N´m (21
ft.lbs.).
(5) Install the serpentine belt (Refer to 7 - COOL-
ING/ACCESSORY DRIVE/DRIVE BELTS - INSTAL-
LATION).
(6) Install the fan shroud.
(7) Install the fan (Refer to 7 - COOLING/EN-
GINE/RADIATOR FAN - INSTALLATION).
(8) Install the radiator crossmember (Refer to 23 -
BODY/EXTERIOR/RADIATOR CROSSMEMBER -
INSTALLATION).
(9) Refill the power steering fluid (Refer to 19 -
STEERING/PUMP - STANDARD PROCEDURE).
INSTALLATION - RETURN HOSE (RESERVOIR
TO THE COOLER)
(1) Install the return hose to the vehicle.
(2) Install the return hose to the pump reservoir.
(3) Install the return hose at the cooler.
(4) Refill the power steering fluid (Refer to 19 -
STEERING/PUMP - STANDARD PROCEDURE).
POWER STEERING PRESSURE
SWITCH
DESCRIPTION
A pressure sensing switch is used in the power
steering system. It is mounted on the high-pressure
steering hose. This switch will be used with both
2.4L and 3.7L engines.
OPERATION
The switch is used on both the 2.4L 4±cylinder and
3.7L V-6 engines.
The power steering pressure switch provides an
input to the Powertrain Control Module (PCM). This
input is provided during periods of high steering
pump load and low engine rpm; such as during park-
ing maneuvers. The PCM increases the idle speed
through the Idle Air Control (IAC) motor. This is
done to prevent the engine from stalling under the
increased load.
When steering pump pressure exceeds 3275 kPa  
690 kPa (475 psi   100 psi), the Normally Closed
(NC) switch will open and the PCM will increase the
engine idle speed. This will prevent the engine from
stalling.
When pump pressure drops to approximately 1379
kPa (200 psi), the switch circuit will re-close and
engine idle speed will return to its previous setting.
REMOVAL
The power steering pressure switch is installed in
the power steering high-pressure hose (Fig. 9).
(1) Remove the high pressure power steering
hose(Refer to 19 - STEERING/PUMP/HOSES -
REMOVAL).
(2) Disconnect electrical connector from power
steering pressure switch.
(3) Place a small container or shop towel beneath
switch to collect any excess fluid.
(4) Remove switch. Use back-up wrench on power
steering line to prevent line bending.
INSTALLATION
(1) Install power steering switch into power steer-
ing line. (Fig. 9)
(2) Tighten to 9.6 N´m (85 in. lbs.) torque.
Fig. 8 HIGH PRESSURE HOSE ASSEMBLY
1 - HIGH PRESSURE POWER STEERING HOSE
2 - MOUNTING BRACKET
3 - POWER STEERING PRESURE SWITCH
19 - 22 PUMPKJ
HOSES (Continued)

LATCH
REMOVAL
(1) Remove the grill. (Refer to 23 - BODY/EXTERI-
OR/GRILLE - REMOVAL)
(2) Remove the latch support bracket bolts and
position the latch assembly aside. (Fig. 1)
(3) Remove the two latch nuts.
(4) Disconnect the release cable.
INSTALLATION
(1) Connect the release cable and install the latch
onto the support bracket.
(2) Install the two nuts and tighten to 12 N´m (9
ft. lbs.).
(3) Install the support bracket and the bolts.
(4) Tighten the bolts to 12 N´m (9 ft. lbs.).
(5) Install the grill. (Refer to 23 - BODY/EXTERI-
OR/GRILLE - INSTALLATION)
LATCH RELEASE CABLE
REMOVAL
(1) Remove the battery. (Refer to 8 - ELECTRI-
CAL/BATTERY SYSTEM/BATTERY - REMOVAL)
(2) Remove the hood latch. (Refer to 23 - BODY/
HOOD/LATCH - REMOVAL)(3) Remove the powertrain control module. (Refer
to 8 - ELECTRICAL/ELECTRONIC CONTROL
MODULES/POWERTRAIN CONTROL MODULE -
REMOVAL)
(4) Remove the hood release handle. (Refer to 23 -
BODY/HOOD/LATCH RELEASE HANDLE -
REMOVAL)
(5) Disconnect the attaching clips and remove the
cable from the inside.
INSTALLATION
(1) Install the cable from the inside and attach the
retaining clips.
(2) Install the hood latch release handle. (Refer to
23 - BODY/HOOD/LATCH RELEASE HANDLE -
INSTALLATION)
(3) Install the powertrain control module. (Refer to
8 - ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/POWERTRAIN CONTROL MODULE -
INSTALLATION)
(4) Install the hood latch. (Refer to 23 - BODY/
HOOD/LATCH - INSTALLATION)
(5) Install the battery. (Refer to 8 - ELECTRICAL/
BATTERY SYSTEM/BATTERY - INSTALLATION)
SUPPORT CYLINDER
REMOVAL
(1) Open the hood and support.
(2) Release the upper and lower clips.
(3) Remove the support cylinder.
INSTALLATION
(1) Install the support cylinder over the ball studs
with the thin end down.
(2) Install the retaining clips and remove the sup-
port from the hood.
LATCH RELEASE HANDLE
REMOVAL
(1) Remove the cowl trim panel. (Refer to 23 -
BODY/INTERIOR/COWL TRIM COVER -
REMOVAL)
(2) Remove the three screws and remove the han-
dle.
(3) Disconnect the hood release cable.
INSTALLATION
(1) Connect the hood release cable to the handle.
(2) Install the handle and install the three screws.
(3) Install the cowl trim cover. (Refer to 23 -
BODY/INTERIOR/COWL TRIM COVER - INSTAL-
LATION)
Fig. 1 RADIATOR CROSSMEMBER
1 - CROSSMEMBER
2 - BOLTS (2)
3 - BOLTS (4)
4 - BOLTS (2)
5 - HOOD LATCH SUPPORT
23 - 120 HOODKJ

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 a/c 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.
5. Improperly installed or
faulty a/c low pressure
switch.5. See A/C Low Pressure Switch/Diagnosis and
Testing in this group. Test the a/c low pressure
switch and tighten or replace, if required.
6. Faulty a/c high pressure
switch.6. See A/C High Pressure Switch/Diagnosis and
Testing in this group. Test the a/c high pressure
switch and replace, if required.
7. Faulty Powertrain Control
Module (PCM).7. (Refer to Appropriate Diagnostic Information).
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.
The low side pressure is
normal or slightly low, and
the high side pressure is too
low.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.
2. Refrigerant flow through
the accumulator is restricted.2. See Accumulator in this group. Replace the
restricted accumulator, if required.
3. Refrigerant flow through
the evaporator coil is
restricted.3. See A/C Evaporator in this group. Replace the
restricted evaporator coil, if required.
24 - 4 HEATING & AIR CONDITIONINGKJ
HEATING & AIR CONDITIONING (Continued)

A/C COMPRESSOR CLUTCH
DESCRIPTION - 3.7L and 2.4L
The compressor clutch assembly consists of a sta-
tionary electromagnetic coil, a rotor bearing and
rotor assembly, and a clutch plate (Fig. 1). The elec-
tromagnetic coil unit and the rotor bearing and rotor
assembly are each retained on the nose of the com-
pressor front housing with snap rings. The clutch
plate is keyed to the compressor shaft and secured
with a nut. These components provide the means to
engage and disengage the compressor from the
engine serpentine accessory drive belt.
OPERATION - 3.7L and 2.4L
When the clutch coil is energized, it magnetically
draws the clutch into contact with the rotor and
drives the compressor shaft. When the coil is not
energized, the rotor freewheels on the clutch rotor
bearing, which is part of the rotor. 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 Heater mode control
switch, the A/C low pressure switch, the A/C high
pressure switch, the compressor clutch relay, 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 - A/C COMPRESSOR
CLUTCH COIL
For circuit descriptions and diagrams, (Refer to
Appropriate Wiring Information). 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, 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 DRB IIItscan tool and (Refer to
Appropriate Diagnostic Information) for testing of the
compressor clutch circuit and PCM control. The fol-
lowing 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
²Compressor clutch relay
²A/C high pressure switch
²A/C low pressure switch
²Powertrain Control Module (PCM).
(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.
STANDARD PROCEDURE - A/C COMPRESSOR
CLUTCH BREAK-IN
After a new compressor clutch has been installed,
cycle the compressor clutch approximately twenty
times (five seconds on, then five seconds off). During
this procedure, set the A/C Heater control to the
Recirculation Mode, the blower motor switch in the
highest speed position, and the engine speed at 1500
Fig. 1 COMPRESSOR CLUTCH - TYPICAL
1 - CLUTCH PLATE
2 - NOT USED ON KJ
3 - ROTOR
4 - COIL
5 - CLUTCH SHIMS
6 - SNAP RING
7 - SNAP RING
24 - 12 CONTROLSKJ

CAUTION: If the snap ring is not fully seated in the
groove it will vibrate out, resulting in a clutch fail-
ure and severe damage to the front housing of the
compressor.
(6) Install the original clutch shims on the com-
pressor shaft.
(7) Install the clutch plate. Install the shaft hex
nut and tighten to 15±20 N´m (11±15 ft. lbs.).
(8) Check the clutch air gap with a feeler gauge
(Fig. 9). If the air gap does not meet the specification,
add or subtract shims as required. The air gap spec-
ification is 0.41 to 0.79 millimeter (0.016 to 0.031
inch).NOTE: The air gap is determined by the spacer
shims. When installing an original, or a new clutch
assembly, try the original shims first. When install-
ing a new clutch onto a compressor that previously
did not have a clutch, use a 1.0, 0.50, and 0.13 mil-
limeter (0.040, 0.020, and 0.005 inch) shims from the
new clutch hardware package that is provided with
the new clutch.
(9) To complete the procedure, (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.
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.
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 Heater mode control
switch, the A/C low pressure switch, and the A/C
high pressure switch. (Refer to 24 - HEATING & AIR
CONDITIONING/CONTROLS/A/C COMPRESSOR
CLUTCH RELAY - DIAGNOSIS AND TESTING)
The compressor clutch relay cannot be repaired
and, if faulty or damaged, it must be replaced.
DIAGNOSIS AND TESTING - COMPRESSOR
CLUTCH RELAY
RELAY TEST
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.
Fig. 8 CLUTCH PULLEY INSTALL
1 - ROTOR BEARING ASSEMBLY
2 - INSTALLER
Fig. 9 CHECK CLUTCH AIR GAP
1 - FEELER GAUGE
KJCONTROLS 24 - 15
A/C COMPRESSOR CLUTCH (Continued)

(2) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 67.5 to 82.5 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 Relay Circuit Test. If not OK,
replace the faulty relay.
RELAY CIRCUIT TEST
For circuit descriptions and diagrams, (Refer to
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
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).
(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
Both the heater-only and A/C heater systems use a
combination of mechanical, electrical, and vacuum
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 features, use, and suggested oper-
ation of these controls.
The heater-only or A/C heater control panel is
located to the right of the instrument cluster on the
instrument panel. The control panel contains a rota-
ry-type temperature control knob, a rotary-type mode
control switch knob, and a rotary-type blower motor
speed switch knob. The control also has a push but-
ton to activate the rear window defogger.
The heater-only or A/C heater control panel cannot
be repaired. If faulty or damaged, the entire unit
must be replaced. The illumination lamps are avail-
able for service replacement.
Fig. 10 COMPRESSOR CLUTCH RELAY
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
24 - 16 CONTROLSKJ
A/C COMPRESSOR CLUTCH RELAY (Continued)

electric cooling fan operations. The switch is located
on the discharge line near the compressor. The
switch is screwed onto a fitting that contains a
Schrader-type valve, which allows the switch to be
serviced without discharging the refrigerant system.
The discharge line fitting is equipped with an O-ring
to seal the switch connection.
OPERATION
The A/C high pressure switch is connected in series
electrically with the A/C low pressure switch between
ground and the Powertrain Control Module (PCM).
The switch contacts open and close causing the PCM
to turn the compressor clutch on and off. This pre-
vents compressor operation when the discharge line
pressure approaches high levels, and also reduces
electrical surging from compressor clutch engage-
ment.
The A/C high pressure switch controls the electric
cooling fan operation by monitoring refrigerant line
pressures. When the discharge line pressure rises
above 1900 to 2200 kPa (280 to 320 psi) the fan will
turn on. The cooling fan will turn off when the dis-
charge line pressure drops to 1600 kPa (235 psi).
The A/C high pressure switch controls the A/C
clutch operation by disengaging the clutch when the
discharge line pressure rises above 3100 to 3375 kPa
(450 to 490 psi). The switch contacts will close and
allow A/C clutch engagement when the discharge line
pressure drops to 1860 to 2275 kPa (270 to 330 psi).
The A/C high pressure switch is a factory-cali-
brated unit. The switch cannot be adjusted or
repaired and, if faulty or damaged, it must be
replaced.
DIAGNOSIS AND TESTING - A/C HIGH
PRESSURE SWITCH
Before performing diagnosis of the A/C high pres-
sure switch, verify that the refrigerant system has
the correct refrigerant charge. (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - STAN-
DARD PROCEDURE - REFRIGERANT SYSTEM
CHARGE)
For circuit descriptions and diagrams, (Refer to
Appropriate Wiring Information).
(1) Disconnect and isolate the battery negative
cable.
(2) Unplug the A/C high pressure switch wire har-
ness connector from the switch on the refrigerant
system fitting.
(3) On the four terminal A/C high pressure switch,
check for continuity between terminals C and D. On
the two terminal A/C high pressure switch, check for
continuity between both terminals of the switch.
There should be continuity. If OK, test and repair theA/C switch sense circuit as required. If not OK,
replace the faulty switch.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Unplug the wire harness connector from the
A/C high pressure switch, which is mounted to a fit-
ting on the non-flexible section of the discharge line
nearest the compressor.
(3) Unscrew the A/C high pressure switch from the
discharge line fitting.
(4) Remove the A/C high pressure switch from the
vehicle.
(5) Remove the O-ring seal from the discharge line
fitting and discard.
INSTALLATION
(1) Lubricate a new O-ring seal with clean refrig-
erant oil and install it on the discharge line fitting.
Use only the specified O-rings as they are made of a
special material for the R-134a system. Use only
refrigerant oil of the type recommended for the com-
pressor in the vehicle(Refer to 24 - HEATING & AIR
CONDITIONING - SPECIFICATIONS). (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING/RE-
FRIGERANT OIL - DESCRIPTION)
(2) Install and tighten the a/c high pressure switch
on the discharge line fitting. The switch should be
hand-tightened onto the discharge line fitting.
(3) Plug the wire harness connector into the a/c
high pressure switch.
(4) Connect the battery negative cable.
A/C LOW PRESSURE SWITCH
DESCRIPTION
The a/c low pressure switch is located on the top of
the accumulator. The switch is screwed onto an accu-
mulator fitting that contains a Schrader-type valve,
which allows the switch to be serviced without dis-
charging the refrigerant system. The accumulator fit-
ting is equipped with an O-ring to seal the switch
connection.
OPERATION
The a/c low pressure switch is connected in series
electrically with the a/c high pressure switch,
between ground and the Powertrain Control Module
(PCM). The switch contacts open and close causing
the PCM to turn the a/c compressor clutch on and
off. This regulates the refrigerant system pressure
and controls evaporator temperature. Controlling the
evaporator temperature prevents condensate water
24 - 18 CONTROLSKJ
A/C HIGH PRESSURE SWITCH (Continued)