Engine bleed fitting JEEP GRAND CHEROKEE 2003 WJ / 2.G Workshop Manual

(2) If complaint was based on noise when braking,
check suspension components. Jounce front and rear
of vehicle and listen for noise that might be caused
by loose, worn or damaged suspension or steering
components.
(3) Inspect brake fluid level and condition. Note
that the brake reservoir fluid level will decrease in
proportion to normal lining wear.Also note that
brake fluid tends to darken over time. This is
normal and should not be mistaken for contam-
ination.
(a) If fluid level is abnormally low, look for evi-
dence of leaks at calipers, brake lines, master cyl-
inder, and HCU.
(b) If fluid appears contaminated, drain out a
sample to examine. System will have to be flushed
if fluid is separated into layers, or contains a sub-
stance other than brake fluid. The system seals,
cups, hoses, master cylinder, and HCU will also
have to be replaced after flushing. Use clean brake
fluid to flush the system.
(4) Check parking brake operation. Verify free
movement and full release of cables and lever. Also
note if vehicle was being operated with parking
brake partially applied.
(5) Check brake pedal operation. Verify that pedal
does not bind and has adequate free play. If pedal
lacks free play, check pedal and power booster for
being loose or for bind condition. Do not road test
until condition is corrected.
(6) Check booster vacuum check valve and hose.
(7) If components checked appear OK, road test
the vehicle.
ROAD TESTING
(1) If complaint involved low brake pedal, pump
pedal and note if it comes back up to normal height.
(2) Check brake pedal response with transmission
in neutral and engine running. Pedal should remain
firm under constant foot pressure.
(3) During road test, make normal and firm brake
stops in 25-40 mph range. Note faulty brake opera-
tion such as low pedal, hard pedal, fade, pedal pulsa-
tion, pull, grab, drag, noise, etc.
(4) Attempt to stop the vehicle with the parking
brake only (do not exceed 25 mph) and note grab,
drag, noise, etc.
PEDAL FALLS AWAY
A brake pedal that falls away under steady foot
pressure is generally the result of a system leak. The
leak point could be at a brake line, fitting, hose, or
caliper. If leakage is severe, fluid will be evident at
or around the leaking component.Internal leakage (seal by-pass) in the master cylin-
der caused by worn or damaged piston cups, may
also be the problem cause.
An internal leak in the ABS system may also be
the problem with no visual fluid leak.
LOW PEDAL
If a low pedal is experienced, pump the pedal sev-
eral times. If the pedal comes back up, the most
likely causes are worn linings, rotors, or calipers are
not sliding on the slide pins. The proper course of
action is to inspect and replace all worn component.
SPONGY PEDAL
A spongy pedal is most often caused by air in the
system. However substandard brake hoses can cause
a spongy pedal. The proper course of action is to
bleed the system, and replace substandard quality
brake hoses if suspected.
HARD PEDAL OR HIGH PEDAL EFFORT
A hard pedal or high pedal effort may be due to
lining that is water soaked, contaminated, glazed, or
badly worn. The power booster, check valve, check
valve seal/grommet or vacuum leak could also cause
a hard pedal or high pedal effort.
PEDAL PULSATION
Pedal pulsation is caused by components that are
loose, or beyond tolerance limits.
The primary cause of pulsation are disc brake
rotors with excessive lateral runout or thickness vari-
ation. Other causes are loose wheel bearings or cali-
pers and worn, damaged tires.
NOTE: Some pedal pulsation may be felt during
ABS activation.
BRAKE DRAG
Brake drag occurs when the lining is in constant
contact with the rotor or drum. Drag can occur at one
wheel, all wheels, fronts only, or rears only.
Drag is a product of incomplete brake release.
Drag can be minor or severe enough to overheat the
linings, rotors and park brake drums.
Minor drag will usually cause slight surface charring
of the lining. It can also generate hard spots in rotors
and park brake drums from the overheat-cool down pro-
cess. In most cases, the rotors, wheels and tires are
quite warm to the touch after the vehicle is stopped.
Severe drag can char the brake lining all the way
through. It can also distort and score rotors to the
point of replacement. The wheels, tires and brake
components will be extremely hot. In severe cases,
the lining may generate smoke as it chars from over-
heating.
WJBRAKES - BASE 5 - 3
BRAKES - BASE (Continued)

NOTE: When ever the high pressure line fittings are
removed from the hydraulic fan drive the o-rings
located on the fittings must be replaced.
(7) Lubricate the o-rings on the fittings with power
steering fluid then connect inlet and outlet high pres-
sure lines to fan drive (Fig. 9). Tighten inlet line to
49 N´m (36 ft. lbs.) tighten outlet line to 29 N´m (21.5
ft. lbs.).
(8) Connect low pressure return hose to fan drive
(Fig. 9).
(9) Lower vehicle.
(10) Install radiator upper hose.
(11) Connect electrical connector for hydraulic fan
control solenoid.
(12) Tighten fan shroud upper mounting bolts to 6
N´m (50 in. lbs.).
(13) Refill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
CAUTION: Do not run engine with power steering
fluid below the full mark in the reservoir. Sever
damage to the hydraulic cooling fan or the engine
can occur.(14) Refill power steering fluid reservoir and bleed
air from steering system (Refer to 19 - STEERING/
PUMP - STANDARD PROCEDURE).
(15) Run engine and check for leaks.
RADIATOR FAN - 4.0L
DESCRIPTION
The radiator cooling fan used on the 4.0L engine is
an hybrid fan design. The hybrid fan system consist
of a low speed viscous driven mechanical fan and a
electrical fan (Fig. 10).
REMOVAL
(1) Disconnect negative battery cable from battery.
(2) The thermal viscous fan drive/fan blade assem-
bly is attached (threaded) to water pump hub shaft.
Remove fan blade/viscous fan drive assembly from
water pump by turning mounting nut counterclock-
wise as viewed from front (Fig. 11). Threads on vis-
cous fan drive areRIGHT HAND.
(3) Do not attempt to remove fan/viscous fan drive
assembly from vehicle at this time.
(4) Do not unbolt fan blade assembly from viscous
fan drive at this time.
(5) Remove fan shroud-to-upper crossmember nuts.
(6) Remove fan shroud and fan blade/viscous fan
drive assembly as a complete unit from vehicle.
Fig. 9 HYDRAULIC LINES/HOSES AND ELECTRICAL
CONNECTOR
1 - LOW PRESSURE RETURN HOSE
2 - HIGH PRESSURE LINE (OUTLET)
3 - HIGH PRESSURE LINE (INLET)
4 - HYDRAULIC FAN DRIVEFig. 10 Radiator Cooling Fan
1 - RADIATOR
2 - ELECTRIC COOLING FAN CONNECTOR
3 - FAN SHROUD
4 - ELECTRIC COOLING FAN
WJENGINE 7 - 31
RADIATOR FAN - 4.7L (Continued)

the radiator to flush the radiator and/or A/C con-
denser of debris.
INSPECTION
The radiator cooling fins should be checked for
damage or deterioration. Inspect cooling fins to make
sure they are not bent or crushed, these areas result
in reduced heat exchange causing the cooling system
to operate at higher temperatures. Inspect the plastic
end tanks for cracks, damage or leaks.
Inspect the radiator neck for damage or distortion.
INSTALLATION
CAUTION: Before installing the radiator or A/C con-
denser, be sure the radiator-to-body and radiator-to-
A/C condenser rubber air seals (Fig. 39) are
properly fastened to their original positions. These
are used at the top, bottom and sides of the radia-
tor and A/C condenser. To prevent overheating,
these seals must be installed to their original posi-
tions.
(1) Equipped with air conditioning: Gently lower
the radiator and fan shroud into the vehicle. Guide
the two radiator alignment dowels through the holes
in the rubber air seals first and then through the A/C
support brackets (Fig. 40). Continue to guide thealignment dowels into the rubber grommets located
in lower radiator crossmember. The holes in the
L-shaped brackets (located on bottom of A/C con-
denser) must be positioned between bottom of rubber
air seals and top of rubber grommets.
(2) Connect the radiator upper and lower hoses
and hose clamps to radiator.
CAUTION: The tangs on the hose clamps must be
positioned straight down.
(3) Install coolant reserve/overflow tank hose at
radiator.
(4) Connect both transmission cooler lines at the
radiator.
(5) Install both radiator mounting bolts.
(6) Install air inlet duct at grill.
(7) Attach electric connector for hydraulic fan con-
trol solenoid.
(8) Install the grill (Refer to 23 - BODY/EXTERI-
OR/GRILLE - INSTALLATION).
(9) Connect the two high pressure lines to the
hydraulic fan drive. Tighten
1¤2in. pressure line fit-
ting to 49 N´m (36 ft. lbs.). and the 3/8 in. pressure
line fitting to 29 N´m (21.5 ft. lbs.).
(10) Connect the low pressure hose to the hydrau-
lic fan drive. Position the spring clamp.
(11) Connect the power steering filter hoses to the
filter. Install new hose clamps.
(12) Rotate the fan blades (by hand) and check for
interference at fan shroud.
(13) Refill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(14) Refill the power steering reservoir and bleed
air from system (Refer to 19 - STEERING/PUMP -
STANDARD PROCEDURE).
(15) Connect battery cable at battery.
(16) Start and warm engine. Check for leaks.
RADIATOR - 4.0L
DESCRIPTION
All vehicles are equipped with a cross flow type
radiator with plastic side tanks (Fig. 36).
Plastic tanks, while stronger than brass, are sub-
ject to damage by impact, such as from tools or
wrenches. Handle radiator with care.
REMOVAL
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND UNDER
PRESSURE. SERIOUS BURNS FROM COOLANT
CAN OCCUR. REFER TO COOLING SYSTEM DRAIN-
ING.
Fig. 35 Radiator Alignment Dowels - Typical
1 - RADIATOR
2 - ALIGNMENT DOWEL
3 - RADIATOR LOWER ISOLATOR
4 - RADIATOR LOWER CROSSMEMBER
7 - 44 ENGINEWJ
RADIATOR - 4.7L (Continued)

(8) Connect negative battery cable at battery.
(9) Before starting engine, operate accelerator
pedal to check for any binding.
SERVO
DESCRIPTION
The servo unit consists of a solenoid valve body,
and a vacuum chamber. The solenoid valve body con-
tains three solenoids:
²Vacuum
²Vent
²Dump
The vacuum chamber contains a diaphragm with a
cable attached to control the throttle linkage.
OPERATION
The Powertrain Control Module (PCM) controls the
solenoid valve body. The solenoid valve body controls
the application and release of vacuum to the dia-
phragm of the vacuum servo. The servo unit cannot
be repaired and is serviced only as a complete assem-
bly.
Power is supplied to the servo's by the PCM
through the brake switch. The PCM controls the
ground path for the vacuum and vent solenoids.The dump solenoid is energized anytime it receives
power. If power to the dump solenoid is interrupted,
the solenoid dumps vacuum in the servo. This pro-
vides a safety backup to the vent and vacuum sole-
noids.
The vacuum and vent solenoids must be grounded
at the PCM to operate. When the PCM grounds the
vacuum servo solenoid, the solenoid allows vacuum
to enter the servo and pull open the throttle plate
using the cable. When the PCM breaks the ground,
the solenoid closes and no more vacuum is allowed to
enter the servo. The PCM also operates the vent sole-
noid via ground. The vent solenoid opens and closes a
passage to bleed or hold vacuum in the servo as
required.
The PCM duty cycles the vacuum and vent sole-
noids to maintain the set speed, or to accelerate and
decelerate the vehicle. To increase throttle opening,
the PCM grounds the vacuum and vent solenoids. To
decrease throttle opening, the PCM removes the
grounds from the vacuum and vent solenoids. When
the brake is released, if vehicle speed exceeds 30
mph to resume, 35 mph to set, and the RES/ACCEL
switch has been depressed, ground for the vent and
vacuum circuits is restored.
REMOVAL
The speed control servo is attached to a bracket.
The bracket and servo assembly are located below
the battery tray.
(1) Disconnect negative battery cable at battery.
(2) Disconnect positive battery cable at battery.
(3) Remove air cleaner housing at top of throttle
body and disconnect servo cable at throttle body.
Refer to Servo Cable Removal/Installation.
(4) Remove battery from battery tray.
(5) Disconnect wiring at battery tray.
(6) Disconnect positive battery cable at Power Dis-
tribution Center (PDC).
(7) Loosen PDC at battery tray.
(8) Remove 4 battery tray bolts. One of these bolts
attaches to speed control bracket flange that sup-
ports battery tray. While removing battery tray, dis-
connect battery temperature sensor electrical
connector at sensor.
(9) Disconnect vacuum line at servo vacuum hose
fitting (Fig. 5) .
(10) Disconnect electrical connector at servo (Fig.
5) .
If servo and mounting bracket are being removed
as one assembly, remove two mounting nuts (Fig. 5) .
These are located above right-front tire. Remove
inner fender clips and pry inner fender back slightly
to gain access to mounting nuts.
Fig. 4 Speed Control Cable at BracketÐ4.7L V-8
Engine
1 - PLASTIC CABLE MOUNT
2 - SPEED CONTROL CABLE
3 - BRACKET
4 - SLIDE FOR REMOVAL
WJSPEED CONTROL 8P - 5
CABLE (Continued)

(4) Install airbag module. Refer to Group 8M, Pas-
sive Restraint Systems.
(5) Connect negative battery cable.
VACUUM RESERVOIR
DESCRIPTION
The vacuum reservoir is a plastic storage tank con-
nected to an engine vacuum source by vacuum lines.
OPERATION
The vacuum reservoir is used to supply the vac-
uum needed to maintain proper speed control opera-
tion when engine vacuum drops, such as in climbing
a grade while driving. A one-way check valve is used
in the vacuum line between the reservoir and the
vacuum source. This check valve is used to trap
engine vacuum in the reservoir. On certain vehicle
applications, this reservoir is shared with the heat-
ing/air-conditioning system. The vacuum reservoir
cannot be repaired and must be replaced if faulty.
DIAGNOSIS AND TESTING - VACUUM
RESERVOIR
(1) Disconnect vacuum hose at speed control servo
and install a vacuum gauge into the disconnected
hose.
(2) Start engine and observe gauge at idle. Vac-
uum gauge should read at least ten inches of mer-
cury.
(3) If vacuum is less than ten inches of mercury,
determine source of leak. Check vacuum line to
engine for leaks. Also check actual engine intake
manifold vacuum. If manifold vacuum does not meet
this requirement, check for poor engine performance
and repair as necessary.
(4) If vacuum line to engine is not leaking, check
for leak at vacuum reservoir. To locate and gain
access to reservoir, refer to Vacuum Reservoir Remov-
al/Installation in this group. Disconnect vacuum line
at reservoir and connect a hand-operated vacuum
pump to reservoir fitting. Apply vacuum. Reservoir
vacuum should not bleed off. If vacuum is being lost,
replace reservoir.
(5) Verify operation of one-way check valve and
check it for leaks.
(a) Locate one-way check valve. The valve is
located in vacuum line between vacuum reservoir
and engine vacuum source. Disconnect vacuum
hoses (lines) at each end of valve.
(b) Connect a hand-operated vacuum pump to
reservoir end of check valve. Apply vacuum. Vac-
uum should not bleed off. If vacuum is being lost,
replace one-way check valve.
(c) Connect a hand-operated vacuum pump to
vacuum source end of check valve. Apply vacuum.
Vacuum should flow through valve. If vacuum is
not flowing, replace one-way check valve. Seal the
fitting at opposite end of valve with a finger and
apply vacuum. If vacuum will not hold, diaphragm
within check valve has ruptured. Replace valve.
REMOVAL
The vacuum reservoir is located in the right/front
corner of the vehicle behind the front bumper fascia
(Fig. 8).
(1) Remove front bumper and grill assembly.
(2) Remove 1 support bolt near front of reservoir
(Fig. 8).
(3) Remove 2 reservoir mounting bolts.
(4) Remove reservoir from vehicle to gain access to
vacuum hose (Fig. 9). Disconnect vacuum hose from
reservoir fitting at rear of reservoir.
Fig. 7 Speed Control Switches
1 - MOUNTING SCREW
2 - SPEED CONTROL SWITCHES
8P - 8 SPEED CONTROLWJ
SWITCH (Continued)

FUEL DELIVERY
DESCRIPTION
The fuel delivery system consists of:
²the fuel pump module containing the electric
fuel pump, fuel gauge sending unit (fuel level sensor)
and a separate fuel filter located at bottom of pump
module
²a separate combination fuel filter/fuel pressure
regulator
²fuel tubes/lines/hoses
²quick-connect fittings
²fuel injector rail
²fuel injectors
²fuel tank
²fuel tank filler/vent tube assembly
²fuel tank filler tube cap
²accelerator pedal
²throttle cable
OPERATION
The fuel tank assembly consists of: the fuel tank,
fuel tank shield, fuel tank straps, fuel pump module
assembly, fuel pump module locknut/gasket, and fuel
tank check valve (refer to Emission Control System
for fuel tank check valve information).
A fuel filler/vent tube assembly using a pressure/
vacuum, 1/4 turn fuel filler cap is used. The fuel
filler tube contains a flap door located below the fuel
fill cap.
Also to be considered part of the fuel system is the
evaporation control system. This is designed to
reduce the emission of fuel vapors into the atmo-
sphere. The description and function of the Evapora-
tive Control System is found in Emission Control
Systems.
Both fuel filters (at bottom of fuel pump module
and within fuel pressure regulator) are designed for
extended service. They do not require normal sched-
uled maintenance. Filters should only be replaced if
a diagnostic procedure indicates to do so.
DIAGNOSIS AND TESTING
FUEL PRESSURE LEAK DOWN TEST
Use this test in conjunction with the Fuel Pump
Pressure Test and Fuel Pump Capacity Test.
Check Valve Operation:The electric fuel pump
outlet contains a one-way check valve to prevent fuel
flow back into the tank and to maintain fuel supply
line pressure (engine warm) when pump is not oper-
ational. It is also used to keep the fuel supply line
full of gasoline when pump is not operational. After
the vehicle has cooled down, fuel pressure may drop
to 0 psi (cold fluid contracts), but liquid gasoline willremain in fuel supply line between the check valve
and fuel injectors.Fuel pressure that has
dropped to 0 psi on a cooled down vehicle
(engine off) is a normal condition.When the elec-
tric fuel pump is activated, fuel pressure should
immediately(1±2 seconds) rise to specification.
Abnormally long periods of cranking to restart a
hotengine that has been shut down for a short
period of time may be caused by:
²Fuel pressure bleeding past a fuel injector(s).
²Fuel pressure bleeding past the check valve in
the fuel pump module.
²A defective fuel filter/pressure regulator.
Two #6539, 5/16º, Fuel Line Pressure Test Adapter
Hose Tools are required for the following tests.
(1) Release fuel system pressure. Refer to Fuel
Pressure Release Procedure.
(2) Raise vehicle.
Fuel Line Identification:The fuel filter/pressure
regulator is located in front of the fuel tank and
above the rear axle. It is transversely mounted to a
chassis crossmember (left-to-right). The filter/regula-
tor is equipped with 3 fuel line fittings (2 at one end
and 1 at the other end). The single fitting facing the
left side of the vehicle is the supply line to the fuel
rail (Fig. 1) . The 2 fittings facing the right side of
the vehicle are connected to the fuel tank. Of these 2
fittings, the fitting towards thefrontis used for fuel
return to the fuel tank. The fitting towards therear
is a pressure line. Thisrearfitting must be discon-
nected for the following step.
(3) See previous step. Disconnect fuel pressure line
atrearof filter/regulator. This is a 5/169quick-con-
nect fitting (Fig. 1) . Refer to Quick-Connect Fittings
for procedures.
(4) Obtain correct Fuel Line Pressure Test Adapter
Hose Tool # 6539 for 5/16º fuel lines. Connect one
end of this Special Tool into the disconnected fuel
pressure line. Connect the other end of the Tool into
fitting on filter/regulator.
(5) Lower vehicle.
(6) Disconnect the fuel inlet line at fuel rail. Refer
to Quick-Connect Fittings for procedures. On some
engines, air cleaner housing removal may be neces-
sary before fuel line disconnection.
(7) Obtain a second Fuel Line Pressure Test
Adapter Hose Tool # 6539 for 5/16º fuel lines. Con-
nect this tool between disconnected fuel line and fuel
rail (Fig. 2) .
(8) Connect the 0-414 kPa (0-60 psi) fuel pressure
test gauge (from Gauge Set 5069) to the test port on
the appropriate Adaptor Tool.NOTE: The DRB III
Scan Tool along with the PEP module, the 500
psi pressure transducer, and the transducer-to-
test port adapter may also be used in place of
the fuel pressure gauge.
14 - 2 FUEL DELIVERYWJ

INSTALLATION
(1) Position and install the power steering cooler
to the vehicle.
(2) Install the three mounting bracket bolts (Fig.
6).
(3) Reconnect the upper hose at cooler (Fig. 6).
(4) Reconnect the lower hose at cooler (Fig. 6).
(5) Connect negative battery cable to battery.
(6) Refill the power steering fluid and bleed the
system,(Refer to 19 - STEERING/PUMP - STAN-
DARD PROCEDURE).
(7) Start engine and check for leaks.
(8) Install the grille opening reinforcement panel
(9) Install the front fascia grille,(Refer to 13 -
FRAMES & BUMPERS/BUMPERS/FRONT FASCIA
- INSTALLATION).
HOSES - 4.0L
DESCRIPTION
DESCRIPTION - PRESSURE LINE
The hose consists of two metal ends and rubber
center section that contains a tuning cable. The
pump end uses a quick connect fitting. Lubircation
must be used on the quick connect nut and o-ring
when installing.
DESCRIPTION - RETURN LINE
Power steering return line is a hose which is
clamped at the pump and the gear.
OPERATION
OPERATION - PRESSURE LINE
Power steering pressure line, is used to transfer
high pressure power steering fluid, from the power
steering pump to the power steering gear on the
4.0L. The 4.7L power steering pressure line, is used
to transfer high pressure power steering fluid, from
the power steering pump to the engine cooling fan
and the steering gear.
OPERATION - RETURN LINE
Power steering return line, is used to transfer low
pressure power steering fluid, from the power steer-
ing gear to the power steering pump.
REMOVAL
(1) Drain the power steering fluid from the reser-
voir.
(2) Remove the air box,(Refer to 9 - ENGINE/AIR
INTAKE SYSTEM/AIR CLEANER HOUSING -
REMOVAL).
(3) Disconnect the power steering pressure hose
from the power steering pump and then the power
steering gear (Fig. 7).
(4) Disconnect the power steering return hose from
the power steering cooler and the reservoir.
(5) Remove the hoses from the vehicle.
INSTALLATION
(1) Install the hoses to the vehicle.
(2) Reconnect the power steering return hose to
the power steering cooler and the reservoir.
(3) Reconnect the power steering pressure hose to
the power steering pump and then the power steer-
ing gear.
(4) Install the air box,(Refer to 9 - ENGINE/AIR
INTAKE SYSTEM/AIR CLEANER HOUSING -
INSTALLATION).
(5) Refill the power steering fluid and bleed the
system,(Refer to 19 - STEERING/PUMP - STAN-
DARD PROCEDURE).
Fig. 7 POWER STEERING HOSES
1 - RETURN HOSE
2 - HIGH PRESSURE HOSE
3 - STEERING GEAR
WJPUMP 19 - 37
FLUID COOLER (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)