2003 JEEP GRAND CHEROKEE service light

INPUT AND LOW RANGE GEARS
Inspect the low range gear pinions and pinion pins.
Replace the low range gear if any of the pins or pin-
ions are worn or damaged.
Inspect the thrust washers, retainer, and snap-
ring. Replace the snap-ring if bent, or distorted.
Replace the thrust washers and retainer if worn,
cracked or damaged in any way.
Examine the input gear carefully. Be sure the gear
teeth and bearing surfaces are in good condition.
Replace the gear if wear or damage is evident.
Check the input gear pilot bearing. Rotate the
bearing and check for roughness or noise. Also check
bearing position in the bore. The bearing should be
recessed approximately 2.5 mm (0.100 in.) below the
top edge of the bore. The bearing should not be
seated at the bottom of the bore. Replace the bearing
if worn, or roughness is evident. Replace both the
gear and bearing if the bearing is a loose fit in the
bore.
GEAR CASE AND RETAINERS
Examine both case halves and retainers carefully.
Replace any retainer or case half if wear, cracks, or
other damage is evident.
Check condition of the low range annulus gear and
the shift rail bushing in the front case (Fig. 32). The
low range annulus gear is not a serviceable part.
Replace the gear and case as an assembly if the gear
is loose, worn, or damaged. The shift rail bushing is
a serviceable part and can be replaced if necessary.
Check the bushing in the rear retainer. Replace the
bushing if worn or scored.
Examine the sealing surfaces of both case halves
and retainers. Small burrs, or scratches on these sur-
faces can be reduced with crocus cloth or a fine tooth
file.
Examine condition of the shift rail bushing in the
front case. If the bushing is worn or damaged, it can
be removed with a blind hole type puller. A replace-
ment bushing can be installed with a suitable size
driver. Recess the bushing slightly below the edge of
the bore but do not seat it all the into the case.
GEARTRAIN
Inspect the mainshaft splines, gear teeth and bear-
ing surfaces carefully for evidence of wear, or dam-
age. Replace the shaft if necessary. do not attempt to
salvage it if damaged.
The shift rail and range fork are an assembly.
Replace both parts if either is damaged. However, the
nylon pads in the fork can be replaced if worn, or
cracked.
Inspect the transfer case snap-rings closely. Do not
attempt to salvage a distorted snap-ring by straight-ening or reshaping it. Replace any snap-ring that is
distorted, or worn.
Inspect the low range gear, input gear and the gear
thrust washers retainer, and snap-ring. The low
range gear is serviced as an assembly only. Replace
the gear if the case or pinions are damaged.
During inspection, also make sure the seal surface
of the input gear is in good condition. Minor nicks on
this surface can be reduced with crocus cloth. How-
ever, replace the gear if the seal surface is severely
scored or worn.
OIL PUMP AND PROGRESSIVE COUPLING
The oil pump and progressive coupling are not ser-
viceable components. Replace the coupling as an
assembly if it is damaged. Replace the oil pump as
an assembly if the gear teeth are worn, or if the
pump has become damaged.
BEARINGS AND SEALS
The transfer case seals should be replaced during
overhaul. Use new seals in the input gear bearing
retainer, front case and rear retainer. Also replace
the yoke seal washer and the detent plug O-ring.
Check condition of each transfer case bearing.
Replace any bearing exhibiting signs of roughness,
wear, or damage.
Fig. 32 Low Range Annulus Gear Location
1 - LOW RANGE ANNULUS GEAR
2 - SHIFT RAIL BUSHING
WJTRANSFER CASE - NV247 21 - 325
TRANSFER CASE - NV247 (Continued)

(4) Remove the screws attaching the supports to
the roof panel.
(5) Separate the supports from the roof panel.
NOTE: If a crossbar needs to be serviced, the for-
ward or rearward supports will have to be removed.
INSTALLATION
(1) Position the supports on the roof panel and
install the screw. Be sure that the gasket is properly
seated.
(2) Position the luggage rack on the supports.
(3) Install the screws attaching the side rails to
the supports.
(4) Position the supports covers on the supports
and press into place.
SIDE VIEW MIRROR GLASS
REMOVAL
(1) With damaged mirror still on vehicle, position
mirror glass down and centered.
(2) Position a wide leverage device between the
bottom edge of the glass and the mirror shell.
(3) Firmly apply pressure in an upward direction
until glass assembly disengages from adapter plate.
(4) Disconnect the heater wire terminal, if
equipped, or the EC plug, if equipped.
INSTALLATION
(1) Connect the heater wire terminal or the EC
plug, if equipped.
(2) Position the replacement glass in the mirror
shell and align the four snap tabs with the four cav-
ities in the shell.
(3) Apply firm pressure inward until the replace-
ment glass assembly engages with the adapter plate.
Correct assembly will result in a firm click. Glass
assembly should exhibit even gaps to the shell when
complete.
(4) Pull lightly on corners of glass assembly to
ensure all four snaps are engaged and there is no
free play.
SIDE VIEW MIRROR
REMOVAL
(1) Remove door trim panel, refer to (Refer to 23 -
BODY/DOOR - FRONT/TRIM PANEL - REMOVAL).
(2) Disengage power mirror harness connector, if
equipped.
(3) Remove mirror flag seal.
(4) Remove nuts attaching mirror to door (Fig. 11).
(5) Separate mirror from door.
INSTALLATION
(1) Position mirror on door. Verify that gasket seal
is properly positioned.
(2) Install nuts attaching mirror to door (Fig. 11).
(3) Install mirror retaining nuts.
(4) Install mirror flag seal.
(5) Engage power mirror harness connector, if
equipped.
(6) Install door trim panel, refer to (Refer to 23 -
BODY/DOOR - FRONT/TRIM PANEL - INSTALLA-
TION).
Fig. 11 Side View Mirror
1 - SIDEVIEW MIRROR
2 - MIRROR FLAG SEAL
3 - CONNECTOR
WJEXTERIOR 23 - 31
LUGGAGE RACK (Continued)

REMOVAL
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) Disconnect and isolate the battery negative
cable.
(2) Roll the glove box down from the instrument
panel. (Refer to 23 - BODY/INSTRUMENT PANEL/
GLOVE BOX - STANDARD PROCEDURE - GLOVE
BOX ROLL DOWN).
NOTE: Be certain to use care not to damage or
remove the glove box hinge bumpers on the lower
instrument panel glove box opening reinforcement
when removing the glove box from the instrument
panel.
(3) Firmly grip both ends of the glove box door,
then twist and pull the door as necessary to disen-
gage the inboard hinge hook from the inboard hinge
pin on the instrument panel and reorient the hook to
the underside of the hinge pin (Fig. 18).(4) Raise the glove box door until it is perpendicu-
lar to the instrument panel.
(5) Twist the door slightly in the counterclockwise
direction and use a jiggling action to disengage the
remaining two hinge hooks from their respective
hinge pins on the instrument panel.
(6) Remove the glove box from 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. 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.
NOTE: Be certain to use care not to damage or
remove the glove box hinge bumpers on the lower
instrument panel glove box opening reinforcement
when installing the glove box onto the instrument
panel.
(1) Position the glove box to the instrument panel
with the outboard hinge hook oriented over the out-
board hinge pin and the center hinge hook oriented
under the center hinge pin (Fig. 18).
(2) Raise the glove box door until it is perpendicu-
lar to the instrument panel.
(3) Firmly grip both ends of the glove box door and
twist the door slightly in the clockwise direction to
engage the inboard glove box hinge hook over the
inboard hinge pin on the instrument panel.
(4) Roll the glove box back up into the instrument
panel. (Refer to 23 - BODY/INSTRUMENT PANEL/
GLOVE BOX - STANDARD PROCEDURE - GLOVE
BOX ROLL DOWN).
(5) Reconnect the battery negative cable.
Fig. 18 Glove Box Remove/Install
1 - GLOVE BOX HINGE HOOKS AND HINGE PINS (3)
WJINSTRUMENT PANEL SYSTEM 23 - 47
GLOVE BOX (Continued)

INSTRUMENT PANEL
STUCTURAL DUCT
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) Remove the instrument panel from the vehicle.
(Refer to 23 - BODY/INSTRUMENT PANEL -
REMOVAL).
(3) Place the instrument panel on a suitable work
surface. Be certain to take the proper precautions to
protect the instrument panel from any possible cos-
metic damage.
(4)
Remove all of the individual components that
remain secured to the instrument panel structural duct
as described elsewhere in this service information.
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) Reinstall all of the individual components that
were removed from the instrument panel structural
duct as described elsewhere in this service informa-
tion.
(2) Reinstall the instrument panel into the vehicle.
(Refer to 23 - BODY/INSTRUMENT PANEL -
INSTALLATION).
(3) Reconnect the battery negative cable.
INSTRUMENT PANEL TOP
COVER
REMOVAL
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) Disconnect and isolate the battery negative
cable.
(2) Using a trim stick or another suitable wide
flat-bladed tool, gently pry the rear edge (farthest
from the windshield) of the top cover up and away
from the instrument panel far enough to disengage
the four snap clip retainers from their receptacles in
the instrument panel top pad (Fig. 22).
(3) Remove the top cover from the top of the
instrument panel.
Fig. 22 Instrument Panel Top Cover Remove/Install
1 - ULTRA LIGHT SENSOR PLUG
2 - SEAL
3 - INSTRUMENT PANEL TOP COVER
WJINSTRUMENT PANEL SYSTEM 23 - 51

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) If the vehicle is not equipped with the optional
automatic headlamps light sensor/vehicle theft secu-
rity system indicator, be certain that the hole plug is
installed in the clearance hole located to the out-
board side of the driver side defroster outlet in the
instrument panel top cover (Fig. 22).
(2) Before installing the top cover onto the top of
the instrument panel, be certain that the rubber top
cover seal is properly positioned on the forward edge
of the top cover panel.
(3) Position the top cover onto the top of the
instrument panel.
(4) Align the four snap clips on the top cover with
the snap clip receptacles in the instrument panel top
pad.
(5) Press firmly downward on the top cover over
each of the four snap clip locations until each of the
snap clips is fully seated in their receptacles in the
instrument panel top pad.
(6) Reconnect the battery negative cable.
INSTRUMENT PANEL TOP PAD
REMOVAL
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) Disconnect and isolate the battery negative
cable.
(2) Remove the trim from the right and left A-pil-
lars. (Refer to 23 - BODY/INTERIOR/A-PILLAR
TRIM - REMOVAL).
(3) Remove the top cover from the instrument
panel. (Refer to 23 - BODY/INSTRUMENT PANEL/
INSTRUMENT PANEL TOP COVER - REMOVAL).
(4) Remove the four nuts that secure the instru-
ment panel top pad to the studs on the dash panel
near the windshield fence line (Fig. 23).
(5) Remove the speakers from the instrument
panel top pad. (Refer to 8 - ELECTRICAL/AUDIO/
SPEAKER - REMOVAL - INSTRUMENT PANEL
SPEAKER).
(6) Disengage the retainer that secures each of the
two instrument panel wire harness speaker take outs
to the mounting hole in the instrument panel top
pad. Tuck the loose ends of these speaker take outs
down the defroster ducts to keep them out of the way
during the remainder of this procedure.
(7) If the vehicle is so equipped, remove the two
screws that secure the automatic headlamp light sen-
sor/vehicle theft security system indicator unit to the
instrument panel top pad just outboard of the driver
side defroster outlet. Move the sensor/indicator unit
towards the windshield to keep it out of the way dur-
ing the remainder of this procedure.
(8) Remove the cluster bezel from the instrument
panel. (Refer to 23 - BODY/INSTRUMENT PANEL/
CLUSTER BEZEL - REMOVAL).
(9) Remove the instrument cluster from the instru-
ment panel. (Refer to 8 - ELECTRICAL/INSTRU-
MENT CLUSTER - REMOVAL).
(10) Remove the steering column opening cover
from the instrument panel. (Refer to 23 - BODY/IN-
STRUMENT PANEL/STEERING COLUMN OPEN-
ING COVER - REMOVAL).
(11) Roll the glove box down from the instrument
panel. (Refer to 23 - BODY/INSTRUMENT PANEL/
GLOVE BOX - STANDARD PROCEDURE - GLOVE
BOX ROLL DOWN).
(12) Remove the end cap from the passenger side
lower outboard end of the instrument panel. (Refer to
23 - BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL END CAP - REMOVAL).
(13) Remove the lower right center bezel from the
instrument panel. (Refer to 23 - BODY/INSTRU-
MENT PANEL/IP LOWER RIGHT CENTER BEZEL
- REMOVAL).
(14) Remove the glove box lamp and switch from
the instrument panel. (Refer to 8 - ELECTRICAL/
LAMPS/LIGHTING - INTERIOR/GLOVE BOX
LAMP/SWITCH - REMOVAL).
23 - 52 INSTRUMENT PANEL SYSTEMWJ
INSTRUMENT PANEL TOP COVER (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

DIAGNOSIS AND TESTING - HEATER
PERFORMANCE
Before performing the following tests, refer to Cool-
ing for the procedures to check the radiator coolant
level, serpentine drive belt tension, radiator air flow
and the radiator fan operation. Also be certain that
the accessory vacuum supply line is connected at the
engine intake manifold for the manual temperature
control system.
MAXIMUM HEATER OUTPUT
Engine coolant is delivered to the heater core
through two heater hoses. With the engine idling at
normal operating temperature, set the temperature
control knob in the full hot position, the mode control
switch knob in the floor heat position, and the blower
motor switch knob in the highest speed position.
Using a test thermometer, check the temperature of
the air being discharged at the HVAC housing floor
outlets. Compare the test thermometer reading to the
Temperature Reference chart.
Temperature Reference
Ambient Air Temperature15.5É C
(60É F)21.1É C
(70É F)26.6É C
(80É F)32.2É C
(90É F)
Minimum Air Temperature at
Floor Outlet62.2É C
(144É F)63.8É C
(147É F)65.5É C
(150É F)67.2É C
(153É F)
If the floor outlet air temperature is too low, refer
to Cooling to check the engine coolant temperature
specifications. Both of the heater hoses should be hot
to the touch. The coolant return heater hose should
be slightly cooler than the coolant supply heater
hose. If the return hose is much cooler than the sup-
ply hose, locate and repair the engine coolant flow
obstruction in the cooling system. Refer to Cooling
for the procedures.
OBSTRUCTED COOLANT FLOW
Possible locations or causes of obstructed coolant
flow:
²Pinched or kinked heater hoses.
²Improper heater hose routing.
²Plugged heater hoses or supply and return ports
at the cooling system connections.
²A plugged heater core.
If proper coolant flow through the cooling system is
verified, and heater outlet air temperature is still
low, a mechanical problem may exist.
MECHANICAL PROBLEMS
Possible locations or causes of insufficient heat:
²An obstructed cowl air intake.
²Obstructed heater system outlets.
²A blend door not functioning properly.
TEMPERATURE CONTROL
If the heater outlet air temperature cannot be
adjusted with the temperature control knob(s) on the
A/C Heater control panel, the following could require
service:
²The A/C heater control.
²The blend door actuator(s).
²The wire harness circuits for the A/C heater con-
trol or the blend door actuator(s).²The blend door(s).
²Improper engine coolant temperature.
STANDARD PROCEDURE - DIODE
REPLACEMENT
(1) Disconnect and isolate the negative battery
cable.
(2) Locate the diode in the harness, and remove
the protective covering.
(3) Remove the diode from the harness, pay atten-
tion to the current flow direction (Fig. 3).
(4) Remove the insulation from the wires in the
harness. Only remove enough insulation to solder in
the new diode.
Fig. 3 DIODE IDENTIFICATION
1 - CURRENT FLOW
2 - BAND AROUND DIODE INDICATES CURRENT FLOW
3 - DIODE AS SHOWN IN THE DIAGRAMS
24 - 6 HEATING & AIR CONDITIONINGWJ
HEATING & AIR CONDITIONING (Continued)

INSTALLATION
INSTALLATION - RECIRCULATION DOOR
VACUUM ACTUATOR
(1) Install the recirculation door vacuum actuator
on the HVAC housing and tighten the mounting
screws to 2.2 N´m (20 in. lbs.).
(2) Engage the recirculation door actuating rod
with the recirculation door lever.
(3) Engage the recirculation door pivot connection
with the door pivot pin.
(4) Plug in the vacuum harness connector to the
recirculation door vacuum actuator.
(5) Install the instrument panel in the vehicle.
Refer to Instrument Panel System for the procedures.
INSTALLATION - RECIRCULATION DOOR
ELECTRIC ACTUATOR
(1) Install the recirculation door actuator on the
recirculation door housing and tighten the mounting
screws to 2.2 N´m (20 in. lbs.).
(2) Install the recirculation door housing on the
HVAC unit and tighten the mounting screws to 2.2
N´m (20 in. lbs.).
(3) Plug in the wire harness connector to the recir-
culation door actuator.
(4) Install the instrument panel in the vehicle.
Refer to Instrument Panel System for the procedures.
VACUUM CHECK VALVE
DESCRIPTION
Two vacuum check valves (non AZC only) are
installed on the vacuum supply system. One is on the
accessory vacuum supply line in the engine compart-
ment, near the vacuum tap on the engine intake
manifold. A second vacuum check valve is located on
the bottom of the HVAC unit behind the passenger
front floor duct on the black vacuum line. The vac-
uum check valves are designed to allow vacuum to
flow in only one direction through the accessory vac-
uum supply circuits.
OPERATION
The use of a vacuum check valve helps to maintain
the system vacuum needed to retain the selected A/C
Heater mode settings. The check valve will prevent
the engine from bleeding down system vacuum
through the intake manifold during extended heavy
engine load (low engine vacuum) operation.
The vacuum check valve cannot be repaired and, if
faulty or damaged, it must be replaced.
REMOVAL
(1) Unplug the HVAC vacuum supply line connec-
tor at the vacuum check valve near the engine intake
manifold vacuum adapter fitting.
(2) Note the orientation of the check valve in the
vacuum supply line for correct installation.
(3) Unplug the vacuum check valve from the vac-
uum supply line fittings.
INSTALLATION
(1) Plug in the vacuum check valve at the vacuum
supply line fittings, noting the orientation of the
check valve in the vacuum supply line for correct
installation.
(2) Plug in the HVAC vacuum supply line connec-
tor at the vacuum check valve near the engine intake
manifold vacuum adapter fitting.
VACUUM RESERVOIR
DESCRIPTION
The vacuum reservoir is mounted in the right front
of the vehicle behind the headlamp mounting module
(Fig. 22). The headlamp mounting module and head-
lamp assembly must be removed from the vehicle to
access the vacuum reservoir for service. Refer to
Lamps/Lighting for the procedures.
OPERATION
Engine vacuum is stored in the vacuum reservoir.
The stored vacuum is used to operate the vacuum-
Fig. 21 RECIRCULATION DOOR HOUSING
1 - RECIRCULATION DOOR HOUSING
2 - ATTACHING SCREWS
24 - 34 CONTROLSWJ
RECIRCULATION DOOR ACTUATOR (Continued)