Vacuum JEEP LIBERTY 2002 KJ / 1.G Repair Manual

(11) Remove module lockring (Fig. 40) using a
brass drift and hammer (counter-clockwise).
(12) Carefully lift upper section of pump module
from fuel tank a few inches(lift upper section
from tank very slowly until rubber gasket can
be retained. If not, gasket will fall into fuel
tank).
(13) Using an approved gas holding tank, drain
fuel tank through fuel pump module opening.
Tank Removal
(1) After draining tank, temporarily place upper
section of fuel pump module back into fuel tank.
(2) Raise vehicle.
(3) If equipped, remove fuel tank skid plate and
tow hooks. Certain equipment packages will also
require removal of the trailer hitch. Refer to Tow
Hooks, Trailer Hitch or Skid Plate in 23, Body for
removal/installation procedures.
(4) Disconnect fuel filter ground strap.
(5) Disconnect fuel filter outlet line from body
retention clip located on frame near front/center of
tank (Fig. 41). Place a small screwdriver into side of
clip and twist for removal. Also disconnect Leak
Detection Pump (LDP) line (Fig. 41) from this clip.(6) Remove both 3/4º hoses at sides of Leak Detec-
tion Pump (LDP) (Fig. 41).
(7) Disconnect 3/4º flow management valve hose
(Fig. 41) at EVAP canister.
(8) Remove fuel fill hose clamp (Fig. 42) at fuel
tank, and disconnect hose from fuel tank.
(9) A third fuel line is attached to bottom of fuel
filter. The disconnection point (quick-connect fitting)
for this 3rd line is approximately 1 foot from front of
tank towards front of vehicle (Fig. 41). Clean connec-
tion point before disconnection. Disconnect by press-
ing on tabs at side of quick-connect fitting. Also
disconnect LDP vent line near this same point.
(10) Disconnect 2 vacuum/vent hoses from plastic
retention clip at left/front of fuel tank line (Fig. 41).
(11) Support tank with a hydraulic jack.
(12) Remove 4 fuel tank strap bolts (Fig. 41) (2 at
front of tank; 2 at rear of tank), and remove both
tank support straps (Fig. 41).
(13) Carefully lower tank a few inches and discon-
nect electrical connector at top of LDP (Fig. 43). To
disconnect electrical connector: Push upward on red
colored tab to unlock. Push on black colored tab
while removing connector.
Fig. 40 TOP OF FUEL PUMP MODULE
1 - LOCK RING
2 - ALIGNMENT NOTCH
3 - FUEL FILTER FITTINGS (2)
4 - ORVR SYSTEM HOSE AND CLAMP
5 - FLOW MANAGEMENT VALVE
6 - ELECTRICAL CONNECTOR
7 - LEAK DETECTION PUMP
8 - FUEL TANK CHECK (CONTROL) VALVE
9 - FUEL PUMP MODULE (UPPER SECTION)Fig. 41 FRONT OF FUEL TANK
1 - TANK MOUNTING BOLTS (4)
2 - TANK MOUNTING STRAPS (2)
3 - LEAK DETECTION PUMP (LDP)
4 - BODY RETENTION CLIP (CENTER)
5 - LDP HOSES
6 - HOSE TO FUEL MANAGEMENT VALVE
7 - BODY RETENTION CLIP (LEFT/FRONT)
8 - QUICK-CONECT FITTING
9 - LDP LINE
14 - 26 FUEL DELIVERYKJ
FUEL TANK (Continued)

(14) Continue lowering tank while guiding remain-
ing hoses and lines.
(15) If fuel tank is to be replaced, remove LDP,
fuel filter and fuel pump module from tank. Refer to
Leak Detection Pump, Fuel Filter and Fuel Pump
Module Removal/Installation procedures.
INSTALLATION
(1) If fuel tank is to be replaced, install LDP, fuel
filter and fuel pump module to tank. Refer to Leak
Detection Pump, Fuel Filter and Fuel Pump Module
Removal/Installation procedures.
(2) Position fuel tank to hydraulic jack.
(3) Raise tank while carefully guiding vent tubes/
hoses through frame rail and crossmember. Before
tank reaches body, connect electrical connector to
Leak Detection Pump (LDP).
(4) Continue raising tank until positioned to body.
(5) Attach two fuel tank mounting straps and 4
mounting bolts. Tighten bolts to 61 N´m (45 ft. lbs.)
torque.
(6) Connect 2 hoses to body retention clip at left/
front of tank.
(7) Connect fuel filter fuel line to main fuel line
(snaps together). After connecting, snap this line into
body retention clip. Also connect LDP vacuum hose
near this point.(8) Install fuel fill hose and hose clamp to fuel
tank fitting. Rotate hose until white painted index
mark on hose (Fig. 42) is located between alignment
notches on fuel tank fitting. Tighten clamp to 3.4
N´m (30 in. lbs.) torque.
(9) Connect fresh air and recirculation lines to fuel
fill tube.
(10) Connect 3/4º lines to Leak Detection Pump
(LDP).
(11) Connect 3/4º flow management valve hose to
EVAP canister.
(12) Snap remaining lines into body retention clip
at front/center of fuel tank.
(13) If equipped, install fuel tank skid plate,
trailer hitch and tow hooks. Refer to Tow Hooks,
Trailer Hitch or Skid Plate in 23, Body for removal/
installation procedures.
(14) Lower vehicle.
(15) Attach (snap on) 2 fuel filter fuel lines to top
of fuel pump module.
(16) Install electrical connector to top of fuel pump
module.
(17) Connect negative battery cable to battery.
(18) Fill fuel tank with fuel.
(19) Start engine and check for fuel leaks near top
of module.
(20) Apply silicone sealant to bottom of fuel pump
module metal access plate.
Fig. 42 FUEL FILL HOSE AT TANK
1 - FUEL FILL HOSE AT TANK
2 - HOSE CLAMP
3 - WHITE PAINTED INDEX MARK
4 - ALIGNMENT NOTCHES
5 - LEFT SIDE OF FUEL TANK
6 - FUEL FILL FITTINGFig. 43 LDP ELECTRICAL CONNECTOR
1 - LEAK DETECTION PUMP (LDP)
2 - ELECTRICAL CONNECTOR
3 - FUEL FILTER
KJFUEL DELIVERY 14 - 27
FUEL TANK (Continued)

INSTALLATION
2.4L
The intake manifold air temperature (IAT) sensor
is installed into the intake manifold plenum at the
rear end of the intake manifold.
(1) Check condition of sensor o-ring.
(2) Clean sensor mounting hole in intake manifold.
(3) Position sensor into intake manifold and rotate
clockwise until past release tab.
(4) Install electrical connector.
3.7L
The intake manifold air temperature (IAT) sensor
is installed into the left side of intake manifold ple-
num (Fig. 16).
(1) Check condition of sensor o-ring.
(2) Clean sensor mounting hole in intake manifold.
(3) Position sensor into intake manifold and rotate
clockwise until past release tab (Fig. 16).
(4) Install electrical connector.
MAP SENSOR
DESCRIPTION
2.4L
The Manifold Absolute Pressure (MAP) sensor is
mounted into the rear of the intake manifold with 1
screw.
3.7L
The Manifold Absolute Pressure (MAP) sensor is
mounted into the front of the intake manifold with 2
screws.
OPERATION
The MAP sensor is used as an input to the Power-
train Control Module (PCM). It contains a silicon
based sensing unit to provide data on the manifold
vacuum that draws the air/fuel mixture into the com-
bustion chamber. The PCM requires this information
to determine injector pulse width and spark advance.
When manifold absolute pressure (MAP) equals
Barometric pressure, the pulse width will be at max-
imum.
A 5 volt reference is supplied from the PCM and
returns a voltage signal to the PCM that reflects
manifold pressure. The zero pressure reading is 0.5V
and full scale is 4.5V. For a pressure swing of 0±15
psi, the voltage changes 4.0V. To operate the sensor,
it is supplied a regulated 4.8 to 5.1 volts. Ground is
provided through the low-noise, sensor return circuit
at the PCM.The MAP sensor input is the number one contrib-
utor to fuel injector pulse width. The most important
function of the MAP sensor is to determine baromet-
ric pressure. The PCM needs to know if the vehicle is
at sea level or at a higher altitude, because the air
density changes with altitude. It will also help to cor-
rect for varying barometric pressure. Barometric
pressure and altitude have a direct inverse correla-
tion; as altitude goes up, barometric goes down. At
key-on, the PCM powers up and looks at MAP volt-
age, and based upon the voltage it sees, it knows the
current barometric pressure (relative to altitude).
Once the engine starts, the PCM looks at the voltage
again, continuously every 12 milliseconds, and com-
pares the current voltage to what it was at key-on.
The difference between current voltage and what it
was at key-on, is manifold vacuum.
During key-on (engine not running) the sensor
reads (updates) barometric pressure. A normal range
can be obtained by monitoring a known good sensor.
As the altitude increases, the air becomes thinner
(less oxygen). If a vehicle is started and driven to a
very different altitude than where it was at key-on,
the barometric pressure needs to be updated. Any
time the PCM sees Wide Open Throttle (WOT), based
upon Throttle Position Sensor (TPS) angle and RPM,
it will update barometric pressure in the MAP mem-
ory cell. With periodic updates, the PCM can make
its calculations more effectively.
The PCM uses the MAP sensor input to aid in cal-
culating the following:
²Manifold pressure
²Barometric pressure
²Engine load
²Injector pulse-width
²Spark-advance programs
²Shift-point strategies (certain automatic trans-
missions only)
²Idle speed
²Decel fuel shutoff
The MAP sensor signal is provided from a single
piezoresistive element located in the center of a dia-
phragm. The element and diaphragm are both made
of silicone. As manifold pressure changes, the dia-
phragm moves causing the element to deflect, which
stresses the silicone. When silicone is exposed to
stress, its resistance changes. As manifold vacuum
increases, the MAP sensor input voltage decreases
proportionally. The sensor also contains electronics
that condition the signal and provide temperature
compensation.
The PCM recognizes a decrease in manifold pres-
sure by monitoring a decrease in voltage from the
reading stored in the barometric pressure memory
cell. The MAP sensor is a linear sensor; meaning as
pressure changes, voltage changes proportionately.
14 - 38 FUEL INJECTIONKJ
INTAKE AIR TEMPERATURE 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)

(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.
24).
(6) Remove throttle body from intake manifold.
(7) Check condition of old throttle body-to-intake
manifold o-ring (Fig. 25).
INSTALLATION
2.4L
(1) Check condition of throttle body-to-intake man-
ifold o-ring. Replace as necessary.
(2) Clean mating surfaces of throttle body and
intake manifold.(3) Install throttle body-to-intake manifold o-ring.
(4) Install throttle body to intake manifold.
(5) Install 3 mounting bolts. Tighten bolts to 12
N´m (105 in. lbs.) torque.
(6) Install control cables.
(7) Install electrical connectors.
(8) Install necessary vacuum lines.
(9) Install air cleaner duct at throttle body.
3.7L
(1) Check condition of throttle body-to-intake man-
ifold o-ring. Replace as necessary.
(2) Clean mating surfaces of throttle body and
intake manifold.
(3) Install throttle body-to-intake manifold o-ring.
(4) Install throttle body to intake manifold.
(5) Install 3 mounting bolts. Tighten bolts to 12
N´m (105 in. lbs.) torque.
(6) Install control cables.
(7) Install electrical connectors.
(8) Install necessary vacuum lines.
(9) Install air cleaner duct at throttle body.
Fig. 24 THROTTLE BODY MOUNTING BOLTS - 3.7L
1 - THROTTLE BODY
2 - MOUNTING BOLTS (3)
Fig. 25 THROTTLE BODY O-RING - 3.7L
1 - INTAKE MANIFOLD
2 - THROTTLE BODY O-RING
14 - 44 FUEL INJECTIONKJ
THROTTLE BODY (Continued)

(14) Remove the two roll down bracket bolts at the
left cowl side panel. (Fig. 6)
(15) Remove the ground strap bolt and disconnect
the restraint module electrical connector. (Fig. 3)
(16) Remove the glove box. (Refer to 23 - BODY/
INSTRUMENT PANEL/GLOVE BOX - REMOVAL)
(17) Remove the two HVAC mounting bolts behind
the center trim. (Fig. 3)
(18) Remove the passenger side trim bezel. (Refer
to 23 - BODY/INSTRUMENT PANEL/IP PASSEN-
GER SIDE BEZEL - REMOVAL)(19) Remove the HVAC mounting bolt above the
glove box striker. (Fig. 4)
(20) Remove the HVAC bolt at the lower outside
corner of the glove box opening. (Fig. 5)
(21) Remove the passenger side cowl trim cover.
(Refer to 23 - BODY/INTERIOR/COWL TRIM
COVER - REMOVAL)
(22) Disconnect the blower resistor electrical con-
nector. (Fig. 5)
(23) Remove the two roll down bracket bolts at the
right cowl side panel.
Fig. 2 PEDAL SUPPORT BRACKET
1 - PEDAL SUPPORT BRACKET
2 - BOLTS
3 - BOLTS
4 - ELECTRICAL CONNECTOR
Fig. 3 HVAC BOLTS
1 - RESTRAINT MODULE
2 - HVAC BOLTS
3 - RADIO WIRE HARNESS
Fig. 4 HVAC UPPER BOLT
1 - BOLT
2 - GLOVE BOX STRIKER
3 - HVAC UNIT
Fig. 5 HVAC CONNECTIONS
1 - GLOVE BOX STRIKER
2 - BLOWER RESISTOR
3 - VACUUM CHECK VALVE
4 - BOLT
23 - 150 INSTRUMENT PANELKJ
INSTRUMENT PANEL ASSEMBLY (Continued)

(24) Disconnect the vacuum check valve and the
vacuum reservoir. (Fig. 5)
(25) Disconnect the blower motor electrical connec-
tor.
(26) Remove the four bolts at the top of the instru-
ment panel connecting to the cowl front panel.
(27) Roll the instrument panel rearward and
remove the wire harness from routing channel in the
rear.
(28) Disconnect the push pin fastener and position
aside the radio wire harness. Note the location of the
harness for installation.
(29) Remove the instrument 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. THISIS 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 instrument panel into the vehicle.
(2) Position the wire harness into the rear routing
channel and roll the instrument panel back against
the cowl.
(3) Position the radio wire harness and seat the
push pin fastener.
NOTE: Position the speaker wires through the
speaker openings.
(4) Install the four bolts at the top of the instru-
ment panel connecting to the cowl front panel and
tighten to 28 N´m (21 ft. lbs.).
(5) Connect the blower motor electrical connector.
(6) Connect the vacuum check valve and the vac-
uum reservoir.
(7) Connect the blower resister electrical connector.
NOTE: Do not push or pull bracket. Tighten at the
rest position.
Fig. 6 INSTRUMENT PANEL ASSEMBLY
1 - TOP BOLTS (4)
2 - CENTER SUPPORT BRACKET
3 - NUTS (4)4 - ROLL DOWN BOLTS (4)
5 - INSTRUMENT PANEL ASSEMBLY
KJINSTRUMENT PANEL 23 - 151
INSTRUMENT PANEL ASSEMBLY (Continued)

INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, SEAT BELT TENSIONER, OR INSTRU-
MENT PANEL COMPONENT DIAGNOSIS OR SER-
VICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT TWO
MINUTES FOR THE AIRBAG SYSTEM CAPACITOR
TO DISCHARGE 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 POSSIBLE PERSONAL INJURY.
(1) Position the appropriate divers side bezels on
either side of the steering column and seat the
attachment clips.
INSTRUMENT PANEL CENTER
BEZEL
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, SEAT BELT TENSIONER, OR INSTRU-
MENT PANEL COMPONENT DIAGNOSIS OR SER-
VICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT TWO
MINUTES FOR THE AIRBAG SYSTEM CAPACITOR
TO DISCHARGE 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 POSSIBLE PERSONAL INJURY.
(1) Remove the ashtray and remove the screw.
(2) Using a trim stick C-4755 or equivalent,
remove the center bezel from the instrument panel
assembly. (Fig. 8)
(3) Disconnect the electrical and vacuum connec-
tors.
INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, SEAT BELT TENSIONER, OR INSTRU-
MENT PANEL COMPONENT DIAGNOSIS OR SER-VICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT TWO
MINUTES FOR THE AIRBAG SYSTEM CAPACITOR
TO DISCHARGE 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 POSSIBLE PERSONAL INJURY.
(1) Connect the electrical and vacuum connectors.
(2) Position the center bezel and seat the retaining
clips starting with the lower clips first.
(3) Install the screw and install the ash tray.
INSTRUMENT PANEL
PASSENGER SIDE BEZEL
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, SEAT BELT TENSIONER, OR INSTRU-
MENT PANEL COMPONENT DIAGNOSIS OR SER-
VICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT TWO
MINUTES FOR THE AIRBAG SYSTEM CAPACITOR
TO DISCHARGE 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 POSSIBLE PERSONAL INJURY.
(1) Remove the two screws.
(2) Using a trim stick C-4755 or equivalent,
release the retaining clips and remove the passenger
side bezel. (Fig. 8)
INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, SEAT BELT TENSIONER, OR INSTRU-
MENT PANEL COMPONENT DIAGNOSIS OR SER-
VICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT TWO
MINUTES FOR THE AIRBAG SYSTEM CAPACITOR
TO DISCHARGE 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 POSSIBLE PERSONAL INJURY.
23 - 154 INSTRUMENT PANELKJ
INSTRUMENT PANEL DRIVER SIDE BEZELS (Continued)

HEATING & AIR CONDITIONING
TABLE OF CONTENTS
page page
HEATING & AIR CONDITIONING
DESCRIPTION
DESCRIPTION - HEATER AND AIR
CONDITIONER........................1
DESCRIPTION - COOLING SYSTEM
REQUIREMENTS.......................1
DESCRIPTION - REFRIGERANT SYSTEM
SERVICE PORT........................2
OPERATION
OPERATION - HEATER AND AIR
CONDITIONER........................2
OPERATION - REFRIGERANT SYSTEM
SERVICE PORT........................2
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - A/C
PERFORMANCE.......................2DIAGNOSIS AND TESTING - HEATER
PERFORMANCE.......................6
DIAGNOSIS AND TESTING - VACUUM
SYSTEM.............................6
STANDARD PROCEDURE - DIODE
REPLACEMENT.......................9
SPECIFICATIONS
A/C APPLICATION TABLE................9
SPECIFICATIONS.....................10
CONTROLS.............................11
DISTRIBUTION..........................29
PLUMBING.............................38
HEATING & AIR
CONDITIONING
DESCRIPTION
DESCRIPTION - HEATER AND AIR
CONDITIONER
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. On heater-only systems, the evaporator coil is
omitted from the housing.
DESCRIPTION - COOLING SYSTEM
REQUIREMENTS
To maintain the performance level of the HVAC
system, the engine cooling system must be properly
maintained. The use of a bug screen is not recom-
mended. Any obstructions in front of the radiator or
condenser will reduce the performance of the air con-
ditioning and engine cooling systems.
The engine cooling system includes the heater core
and the heater hoses. Refer to Engine Cooling for
more information before the opening of, or attempt-
ing any service to the engine cooling system.
Fig. 1 Blend Door
1 - DEFROSTER DOOR
2- HEATER CORE
3- BLEND DOORS
4- BLOWER MOTOR HOUSING
5- EVAPORATOR (A/C ONLY)
6- LOWER HVAC CASE ASSEMBLY
KJHEATING & AIR CONDITIONING 24 - 1

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.
OPERATION
OPERATION - HEATER AND AIR CONDITIONER
The heater and optional air conditioner are blend-
air type systems. In a blend-air system, a blend door
controls the amount of unconditioned air (or cooled
air from the evaporator on models with air condition-
ing) 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
temperature by controlling an electric actuator,
which moves the blend door. This allows an almost
immediate control of the output air temperature of
the system.
The mode control knob on the heater-only or A/C
Heater control panel is used to direct the conditioned
air to the selected system outlets. Both mode control
switches use engine vacuum to control the mode
doors, which are operated by vacuum actuators.
On all vehicles, the outside air intake can be shut
off by selecting the Recirculation Mode with the
mode control knob. This will operate a vacuum actu-
ated recirculation door that closes off the outside
fresh air intake and recirculates the air that is
already inside the vehicle.
The optional air conditioner for all models is
designed for the use of non-CFC, R-134a refrigerant.
The air conditioning system has an evaporator to cool
and dehumidify the incoming air prior to blending it
with the heated air. This air conditioning system
uses a fixed orifice tube in the liquid line near the
condenser outlet tube to meter refrigerant flow to the
evaporator coil. To maintain minimum evaporator
temperature and prevent evaporator freezing, the
A/C low pressure switch on the accumulator cycles
the compressor clutch.
OPERATION - REFRIGERANT SYSTEM SERVICE
PORT
The high pressure service port is located on the
refrigerant line, near the discharge port of the com-
pressor. The low pressure service port is located on
the liquid line at the side of the engine compartment,
near the condensor.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 humidity air. The evaporator, located in the
HVAC housing on the dash panel below the instru-
ment panel, is cooled to temperatures near the freez-
ing 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 temper-
ature of the air delivered to the interior of the vehi-
cle. It is important to understand the effect that
humidity has on the performance of the air condition-
ing 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 evapo-
rator fins. Condensing the moisture in the air trans-
fers heat energy into the evaporator 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.
However, evaporator capacity used to reduce the
amount of moisture in the air is not wasted. Remov-
ing some of the moisture out of the air entering the
vehicle adds to the comfort of the passengers.
Although, an owner may expect too much from the
air conditioning system on humid days. A perfor-
mance test is the best way to determine whether the
system is performing up to standard. This test also
provides valuable clues as to the possible cause of
trouble with the air conditioning system.
Before proceeding, (Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING - WARNING) and
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - CAUTION). The air temperature in
the test room and in the vehicle must be a minimum
of 21É C (70É F) for this test.
24 - 2 HEATING & AIR CONDITIONINGKJ
HEATING & AIR CONDITIONING (Continued)