check engine DODGE NEON 2000 Service Repair Manual

PUMP MODE:The pump is cycled at a fixed rate
to achieve a rapid pressure build in order to shorten
the overall test time.
TEST MODE:The solenoid is energized with a
fixed duration pulse. Subsequent fixed pulses occur
when the diaphragm reaches the switch closure
point.
The spring in the pump is set so that the system
will achieve an equalized pressure of about 7.5 inches
of water.
When the pump starts, the cycle rate is quite high.
As the system becomes pressurized, pump rate drops.
If there is no leak, the pump will quit. If there is a
leak, the test is terminated at the end of the test
mode.If there is no leak, the purge monitor is run. If the
cycle rate increases due to the flow through the
purge system, the test is passed and the diagnostic is
complete.
The canister vent valve will unseal the system
after completion of the test sequence as the pump
diaphragm assembly moves to the full travel position.
LEAK DETECTION PUMP PRESSURE SWITCH
OPERATION
The leak detection pump LDP assembly incorpo-
rates two primary functions: it detects a leak in the
evaporative system, and it seals the evaporative sys-
tem so that the required leak detection monitor test
can be run.
The primary components within the leak detection
pump assembly are: a three-port leak detection sole-
noid valve, a pump assembly that includes a spring
loaded diaphragm, a reed switch which is used to
monitor the pump diaphragm movement (position),
two check valves, and a spring loaded vent seal
valve.
The three-port LDP solenoid valve is used to
expose either engine vacuum or atmospheric pressure
to the top side of the leak detection pump diaphragm.
When the LDP solenoid valve is deenergized its
port (opening) to engine vacuum is blocked off. This
allows ambient air (atmospheric pressure) to enter
the top of the pump diaphragm. The spring load on
the diaphragm will push the diaphragm down, as
long as there is no pressure present in the rest of the
evaporative system. If there is sufficient evaporative
system pressure present, then the pump diaphragm
will stay in the ªupº position. If the evaporative sys-
tem pressure decays, then the pump diaphragm will
eventually fall. The rate of this decent is dependent
upon the size of the evaporative system leak (Large
or small).
When the LDP solenoid valve is energized the port
(opening) to atmosphere is blocked off. At the same
time, the port to engine vacuum is opened. Engine
vacuum replaces atmospheric pressure. When engine
vacuum is sufficient, it over comes the spring pres-
sure load on the pump diaphragm and causes the
diaphragm to rise to its ªupº position. The reed
switch will change state depending upon the position
of the pump diaphragm.
If the diaphragm is in the ªupº position the reed
switch will be in its ªopenº state. This means that
the 12 volt signal sense to the PCM is interrupted.
Zero volts is detected by the PCM. If the pump dia-
phragm is in the ªdownº position the reed switch will
be in its ªclosedº state. 12 volts is sent to the PCM
via the switch sense circuit.
Fig. 1 EVAP Canister
Fig. 2 Proportional Purge Solenoid
PLEMISSION CONTROL SYSTEMS 25 - 27
DESCRIPTION AND OPERATION (Continued)

The check valves are one-way valves. The first
check valve is used to draw outside air into the lower
chamber of the LDP (the space that is below the
pump diaphragm). The second check valve is used to
vent this outside air, which has become pressurized
from the fall of the pump diaphragm, into the evap-
orative system.
The spring loaded vent seal valve, inside the LDP
is used to seal off the evaporative system. When the
pump diaphragm is in the ªupº position the spring
pushes the vent seal valve closed. The vent seal valve
opens only when the pump diaphragm is in its ªfull
downº position. When the pump assembly is in its
pump mode the pump diaphragm is not allowed to
descend (fall) so far as to allow the vent seal valve to
open. This allows the leak detection pump to develop
the required pressure within the evaporative system
for system leak testing.
A pressure build up within the evaporative system
may cause pressure on the lower side of the LDP dia-
phragm. This will cause the LDP diaphragm to
remain in its ªupº position (stuck in the up position).
This condition can occur even when the solenoid
valve is deenergized. This condition can be caused by
previous cycling (pumping) of the LDP by the techni-
cian (dealer test). Another way that this condition is
created is immediately following the running of the
vehicle evaporative system monitor. In this case, the
PCM has not yet opened the proportional purge sole-
noid in order to vent the pressure that has been built
up in the evaporative system to the engine combus-
tion system. The technician will need to vent the
evaporative system pressure via the vehicle fuel filler
cap and its fuel filler secondary seal (if so equipped
in the fuel filler neck). This will allow the technician
to cycle the LDP and to watch switch state changes.
After passing the leak detection phase of the test,
system pressure is maintained until the purge sys-
tem is activated, in effect creating a leak. If the dia-
phragm falls (as is expected), causing the reed switch
to change state, then the diagnostic test is completed.
When of the evaporative system leak monitor
begins its various tests, a test is performed to deter-
mine that no part of the evaporative system is
blocked. In this test, the LDP is cycled (pumped) a
calibrated (few) number of times. Pressure should not
build up in the evaporative system. If pressure is
present, then LDP diaphragm is forced to stay in its
ªupº position. The reed switch now stays open and
the PCM senses this open (incorrect) state. The evap-
orative system monitor will fail the test because of a
detected obstruction within the system.
Possible causes:
²Open or shorted LDP switch sense circuit
²Leak Detection Pump switch failure²Open fused ignition switch output
²Restricted, disconnected, or blocked manifold
vacuum source
²Obstruction of hoses or lines
²PCM failure
POSITIVE CRANKCASE VENTILATION (PCV)
SYSTEMS
DESCRIPTION
OPERATION
Intake manifold vacuum removes crankcase vapors
and piston blow-by from the engine. The emissions
pass through the PCV valve into the intake manifold
where they become part of the calibrated air-fuel
mixture. They are burned and expelled with the
exhaust gases. The air cleaner supplies make up air
when the engine does not have enough vapor or
blow-by gases. In this system, fresh air does not
enter the crankcase.
POSITIVE CRANKCASE VENTILATION VALVE
OPERATION
The PCV valve contains a spring loaded plunger.
The plunger meters the amount of crankcase vapors
routed into the combustion chamber based on intake
manifold vacuum.
When the engine is not operating or during an
engine backfire, the spring forces the plunger back
against the seat. This prevents vapors from flowing
through the valve (Fig. 4).
When the engine is at idle or cruising, high mani-
fold vacuum is present. At these times manifold vac-
uum is able to completely compress the spring and
Fig. 3 PCV System
25 - 28 EMISSION CONTROL SYSTEMSPL
DESCRIPTION AND OPERATION (Continued)

INSTALLATION
(1) Install EVAP canister to Bracket (Fig. 8).
(2) Install 2 nuts to EVAP canister and bracket
and tighten nuts to 6.7 N´m (60 in. lbs.).
(3) Connect hoses.
(4) Install EVAP canister and bracket to vehicle
and tighten nut 22.4 N´m (250 in. lbs.).
(5) Lower vehicle.
(6) Connect negative battery cable.
LEAK DETECTION PUMP
REMOVAL
(1) Raise and support vehicle on a hoist.
(2) Push locking tab on electrical connector to
unlock and remove connector.
(3) loosen the sway bar bracket to remove the
pump bracket.
(4) Remove pump and bracket as an assembly.
(5) Disconnect lines from LDP.
(6) Remove filter.
(7) Remove pump from bracket.
INSTALLATION
(1) Install pump to bracket and tighten bolts to 1.2
N´m (10.6 in. lbs.).
(2) Install filter and tighten to 2.8 N´m (25 in.
lbs.).
(3)Before installing hoses to LDP, make sure
they are not cracked or split. If a hose leaks, it
will cause the Check Engine Lamp to illumi-
nate.Connect lines to the LDP.
NOTE: The LDP bracket must be between the rail
and sway bar bracket.
(4) Install pump and bracket assembly to body and
tighten bolts to 5.0 N´m (45 in. lbs.).
(5) Install sway bar bracket bolt and tighten bolts
to 33.8 N´m (25 ft. lbs.).
(6) Install electrical connector to pump and push
locking tab to lock.
(7) Lower vehicle(8) Use the DRB scan tool, verify proper operation
of LDP.
PROPORTIONAL PURGE SOLENOID VALVE
The solenoid attaches to a bracket near the steer-
ing gear (Fig. 9). The solenoid will not operate unless
it is installed correctly.
REMOVAL
(1) Raise vehicle and support.
(2) Disconnect electrical connector from solenoid.
(3) Disconnect vacuum tubes from solenoid.
(4) Remove solenoid from bracket.
INSTALLATION
The top of the solenoid has TOP printed on it. The
solenoid will not operate unless it is installed cor-
rectly.
(1) Install solenoid on bracket.
(2) Connect vacuum tube to solenoid.
(3) Connect electrical connector to solenoid.
(4) Lower vehicle.
Fig. 9 Proportional Purge Solenoid Valve
25 - 30 EMISSION CONTROL SYSTEMSPL
REMOVAL AND INSTALLATION (Continued)

(2) Install the five screws holding cowl panel to
cowl at base of windshield opening.
(3) Push the hood to cowl seal over the forward
flange of the cowl cover and cowl plenum.
(4) Install windshield wiper arms, refer to Group
8K, Windshield Wiper and Washer Systems, for
proper procedures.
FRONT WHEELHOUSE SPLASH SHIELD
REMOVAL
(1) Hoist and support vehicle on safety stands.
(2) Remove front wheel.
(3) Remove push-in fasteners attaching splash
shield to frame rail forward of suspension (Fig. 24).
(4) Remove push in fasteners attaching splash
shield to frame rail rearward of suspension.
(5) Remove screws attaching wheelhouse splash
shield to front fender.
(6) Remove splash shield from vehicle.
INSTALLATION
(1) Place splash shield in position on vehicle.
(2) Install screws attaching wheelhouse splash
shield to front fender.
(3) Install push in fasteners attaching splash
shield to frame rail rearward of suspension.
(4) Install push in fasteners attaching splash
shield to frame rail forward of suspension.
(5) Install front wheel.
(6) Lower vehicle.
FENDER
REMOVAL
(1) Remove headlamp housing.
(2) Right side of vehicle remove pulley splash
shield.(3) Remove inner splash shield.
(4) Remove fender to fascia nuts.
(5) Remove fender bolt to lower rocker panel.
(6) Remove fender bolt to lower cowl.
(7) Pull fascia away from fender.
(8) Remove bolts attaching fender to upper rail.
(9) Remove fender from vehicle (Fig. 25).
INSTALLATION
(1) Place fender in position on vehicle.
(2) Start the center upper rail bolt.
(3) From inside engine compartment, install all
the bolts attaching fender to upper rail and tighten.
(4) Install lower cowl panel bolt to fender.
(5) Install rocker panel bolt to fender.
(6) Place fascia into position.
(7) Install fender to fascia nuts.
(8) Install inner splash shield.
(9) Install right side pulley splash shield.
(10) Install headlamp assembly.
(11) Check fender for flush and gap.
EXTERIOR BADGEING ATTACHED WITH
DOUBLE SIDED FOAM TAPE
REMOVAL
(1) Mark reference points before removing.
(2) Using a heat gun gently apply heat in a circu-
lar motion to loosen the adhesive bond.
(3) Using a nonmetallic prying device, such as a
plastic or wood trim stick gently pry up at corners
and remove.
(4) Clean off all traces of adhesive or double sided
tape from the panel with a general purpose adhesive
remover.
INSTALLATION
(1) Clean panel surface with isopropy alcohol.
(2) Align badgeing to reference points.
(3) Install and press securely to full adhesive con-
tact
(4) Clean away any reference points.
EXTERIOR BADGEING/TAPE STRIPES
ATTACHED WITH ADHESIVES
REMOVAL
(1) Mark reference points before removing.
(2) Using a heat gun gently apply heat in a circu-
lar motion to loosen the adhesive bond.
(3) With your fingernail lift up and peel away
badgeing /tape from panel, using a heat gun as you
go.
(4) Clean off all traces of adhesive from the pan-
el(s) with a general purpose adhesive remover.
Fig. 23 Cowl Cover
1 ± COWL TOP SCREEN
23 - 28 BODYPL
REMOVAL AND INSTALLATION (Continued)

SPECIFICATIONS
TABLE OF CONTENTS
page page
SPECIFICATIONS
BODY LUBRICATION SPECIFICATIONS........60
BODY GAP AND FLUSH MEASUREMENTS.....61
BODY OPENING DIMENSION...............62BODY SEALING LOCATIONS................64
STRUCTURAL ADHESIVE LOCATIONS........74
TORQUE SPECIFICATIONS.................76
WELD LOCATIONS.......................77
SPECIFICATIONS
BODY LUBRICATION SPECIFICATIONS
LUBRICATION REQUIREMENTS
Body mechanisms and linkages should be
inspected, cleaned, and lubricated, as required, to
maintain ease of operation and to provide protection
against rust and wear. When performing other under
hood services, the hood latch release mechanism and
safety catch should be inspected, cleaned, and lubri-
cated. During the winter season, external door lock
cylinders should be lubricated to assure proper oper-
ation when exposed to water and ice.
Prior to the application of any lubricant, the parts
concerned should be wiped clean to remove dust and
grit. If necessary, a suitable solvent can be used to
clean the item to be lubricated. After lubricating a
component, any excess oil or grease should be
removed.
LUBRICANT APPLICATION
DOOR LOCK CYLINDERS
(1) Apply a small amount of lubricant directly into
the lock cylinder.
(2) Apply a small amount of lubricant to the key.
(3) Insert key into lock cylinder and cycle the
mechanism from the locked to the unlocked position.
NOTE: Do not add more lubricant.
(4) Cycle the lock cylinder mechanism several
times to allow the lubricant to flow throughout the
cylinder.
(5) Wipe all lubricant from exterior of lock cylinder
and key.ALL OTHER BODY MECHANISMS
(1) Clean component as described above.
(2) Apply specified lubricant to all pivoting and
sliding contact areas of component.
LUBRICANT USAGE
ENGINE OIL
²Door Hinges ± Hinge Pin and Pivot Contact
Areas
²Hood Hinges ± Pivot Points
²Liftgate Hinges
²Decklid Hinges
MOPARTSPRAY WHITE CUBE OR EQUIVALENT
²Door Check Straps
²Liftgate Latches
²Liftgate Prop Pivots
²Ash Receiver
²Fuel Filler Door Remote Control Latch Mecha-
nism
²Parking Brake Mechanism
²Sliding Seat Tracks
²Decklid Latch
MOPARTMultipurpose GREASE OR EQUIVALENT
²All Other Hood Mechanisms
MOPARTLOCK CYLINDER LUBRICANT OR
EQUIVALENT
²Door Lock Cylinders
²Decklid Lock Cylinder
23 - 60 BODYPL

HEATING AND AIR CONDITIONING
TABLE OF CONTENTS
page page
GENERAL INFORMATION
A/C APPLICATION TABLE...................2
HEATER AND AIR CONDITIONING CONTROL...2
HEATER AND AIR CONDITIONING............2
INTRODUCTION..........................3
SAFETY PRECAUTIONS AND WARNINGS......4
DESCRIPTION AND OPERATION
A/C REFRIGERANT LINES..................4
BLOWER MOTOR RESISTOR................5
COMPRESSOR...........................5
COMPRESSOR FRONT SHAFT SEAL..........6
CONDENSATION DRAIN TUBE...............6
ENGINE COOLING SYSTEM REQUIREMENTS...6
EVAPORATOR PROBE......................6
HANDLING TUBING AND FITTINGS...........6
HIGH PRESSURE CUT OUT SWITCH..........6
LOW PRESSURE CUT OFF SWITCH..........6
SIDE WINDOW DEMISTERS................7
SYSTEM AIRFLOW........................7
SYSTEM OIL LEVEL.......................7
VACUUM CONTROL SYSTEM................8
DIAGNOSIS AND TESTING
A/C PERFORMANCE TEST..................9
BLOWER MOTOR ELECTRICAL DIAGNOSIS....9
BLOWER MOTOR VIBRATION AND/OR
NOISE DIAGNOSIS.....................11
COMPRESSOR NOISE DIAGNOSIS..........11
EVAPORATOR PROBE TEST................11
EXPANSION VALVE.......................11
HEATER PERFORMANCE TEST.............13
LOW PRESSURE CUT OFF SWITCH.........14
SYSTEM CHARGE LEVEL TEST.............14
VACUUM CONTROL SYSTEM...............15
SERVICE PROCEDURES
CHARGING A/C SYSTEM..................17EVACUATING REFRIGERANT SYSTEM........18
R-134a REFRIGERANT....................19
SERVICING REFRIGERANT OIL LEVEL.......19
SYSTEM LEAK CHECKING.................20
REMOVAL AND INSTALLATION
A/C FILTER/DRIER.......................20
A/C SERVICE PORT VALVE CORES..........21
BLOWER MOTOR AND WHEEL ASSEMBLY....21
BLOWER MOTOR RESISTOR...............22
BLOWER MOTOR WHEEL.................22
COMPRESSOR..........................22
COMPRESSOR CLUTCH/COIL ASSEMBLY.....23
CONDENSATION DRAIN TUBE..............25
CONDENSER............................25
DISCHARGE LINE........................26
EVAPORATOR...........................26
EVAPORATOR PROBE.....................26
EXPANSION VALVE.......................27
HEATER CORE..........................28
HEATER HOSES.........................28
HIGH PRESSURE CUT OUT SWITCH.........29
HIGH PRESSURE RELIEF VALVE............29
LIQUID LINE............................29
LOW PRESSURE CUT OFF SWITCH.........29
MODE CONTROL CABLE..................30
RECIRCULATION DOOR ACTUATOR.........31
SUCTION LINE..........................31
TEMPERATURE CONTROL CABLE...........32
UNIT HOUSING..........................32
DISASSEMBLY AND ASSEMBLY
HEATER-A/C HOUSING....................34
ADJUSTMENTS
MODE CONTROL CABLE..................34
TEMPERATURE CONTROL CABLE...........34
PLHEATING AND AIR CONDITIONING 24 - 1

BLOWER MOTOR VIBRATION AND/OR NOISE
DIAGNOSIS
The resistor block supplies the blower motor with
varied voltage (low and middle speeds) or battery
voltage (high speed).
CAUTION: Stay clear of the blower motor and resis-
tor block (Hot). Do not operate the blower motor
with the resistor block removed from the heater-A/C
housing.
Refer to the Blower Motor Vibration/Noise chart
for diagnosis.
COMPRESSOR NOISE DIAGNOSIS
Excessive noise while the A/C is being used, can be
caused by loose mounts, loose clutch, or high operat-
ing pressure. Verify compressor drive belt condition,
proper refrigerant charge and head pressure before
compressor repair is performed.
If the A/C drive belt slips at initial start-up, it does
not necessarily mean the compressor has failed.
With the close tolerances of a compressor it is pos-
sible to experience a temporary lockup. The longer
the A/C system is inactive, the more likely the condi-
tion to occur.
This condition is the result of normal refrigerant
movement within the A/C system caused by temper-
ature changes. The refrigerant movement may wash
the oil out of the compressor.
EVAPORATOR PROBE TEST
The work area and vehicle must be between 16É C
(60É F) and 32É C (90É F) when testing the switch.
(1) Disconnect the three wire connector from the
evaporator probe lead located behind the glove box
(Fig. 12).
(2) Start engine and set A/C to low blower motor
speed, panel, full cool, and RECIRC.
(3) Using a voltmeter, check for battery voltage
between Pin 1 and 2. If no voltage is detected, there
is no power to the switch. Check wiring and fuses.
Refer to Group 8W, Wiring Diagrams for circuit diag-
nosis.
(4) Using a voltmeter, check for battery voltage
between Pin 1 and Pin 3. If no voltage is detected,
there is no voltage from the Powertrain Control Mod-
ule. Refer to Group 8W, Wiring Diagrams. If voltage
is OK, connect a jumper wire between Pin 1 and Pin
3. The compressor clutch should engage. If the clutch
engages, remove the jumper wire immediately and go
to Step 5. If the compressor clutch does not engage,
check the operation of the clutch and repair as nec-
essary.(5) If compressor clutch engages, connect the evap-
orator probe 3-way connector. The compressor clutch
should engage or cycle depending on evaporator tem-
perature. If OK, go to Step 6. If not OK, replace the
clutch cycling switch.
(6) The engine running and the A/C set to:
²Blower motor on low speed
²Panel position
²Full cool
²RECIRC.
Close all doors and windows. Place a thermometer in
the center discharge vent.
(7) If the clutch does not begin to cycle off between
2É C to 7É C (35É F to 45É F), verify that the evapo-
rator probe is fully installed and not loose in evapo-
rator. If it is not properly installed, install probe and
retest outlet temperature. If the evaporator probe is
properly installed, replace the clutch cycling switch.
EXPANSION VALVE
NOTE: Expansion valve tests should be performed
after compressor tests.
Liquid CO2 is required to test the expansion
valve. It is available from most welding supply facil-
ities. CO2 is also available from companies which
service and sell fire extinguishers.
Review Safety Precautions and Warnings in the
General Information section of this Group. The work
area and vehicle must be 21É to 27ÉC (70É to 85ÉF)
when testing expansion valve. To test the expansion
valve:
(1) Connect a charging station or manifold gauge
set to the refrigerant system service ports.
(2) Disconnect wire connector at low pressure cut-
off switch (Fig. 13). Using a jumper wire, jump ter-
minals inside wire connector boot.
(3) Close all doors, windows and vents to the pas-
senger compartment.
(4) Set Heater-A/C control to A/C, full heat, floor,
RECIRC. and high blower.
(5) Start the engine and hold the idle speed (1000
rpm). After the engine has reached running temper-
ature, allow the passenger compartment to heat up.
This will create the need for maximum refrigerant
flow into the evaporator.
(6) If the refrigerant charge is sufficient, discharge
(high pressure) gauge should read 965 to 2620 kPa
(140 to 380 psi). Suction (low pressure) gauge should
read 103 to 2417 kPa (15 to 35 psi). If system cannot
achieve proper pressure readings, replace the expan-
sion valve. If pressure is correct, proceed with test.
PLHEATING AND AIR CONDITIONING 24 - 11
DIAGNOSIS AND TESTING (Continued)

WARNING: PROTECT SKIN AND EYES FROM CON-
TACTING CO2 PERSONAL INJURY CAN RESULT.
(7) If suction side low pressure is within specified
range, freeze the expansion valve control head (Fig.
13) for 30 seconds. Use a super cold substance (liquid
CO2).Do not spray refrigerant on the expansion
valve for this test.Suction side low pressure should
drop to 34.5 kPa (5 psi) If not, replace expansion
valve.(8) Allow expansion valve to thaw. The low pres-
sure gauge reading should stabilize at 103 to 241
kPa (15 to 35 psi). If not, replace expansion valve.
(9) When expansion valve test is complete, test
A/C overall performance. Refer to the Heater and A/C
Performance Test in this section. Remove all test
equipment before returning vehicle to use.
HEATER PERFORMANCE TEST
PRE-DIAGNOSTIC PREPARATIONS
Review Safety Precautions and Warnings in this
group before performing the following procedures.
Check the coolant level, drive belt tension, vacuum
line connections, radiator air flow and fan operation.
Start engine and allow to warm up to normal tem-
perature.
WARNING: DO NOT REMOVE RADIATOR CAP
WHEN ENGINE IS HOT, PERSONAL INJURY CAN
RESULT.
If vehicle has been run recently, wait 15 minutes
before removing cap. Place a rag over the cap and
turn it to the first safety stop. Allow pressure to
escape through the overflow tube. When the system
stabilizes, remove the cap completely.
MAXIMUM HEATER OUTPUT: TEST AND ACTION
Engine coolant is provided to the heater system by
two 16 mm (5/8 inch inside diameter) heater hoses.
With engine idling at normal running temperature,
set the control to maximum heat, floor, and high
blower setting. Using a test thermometer, check the
air temperature coming from the floor outlets, refer
to Temperature Reference chart.
If the floor outlet air temperature is insufficient,
refer to Group 7, Cooling Systems for specifications.
Both heater hoses should be HOT to the touch (cool-
ant return hose should be slightly cooler than the
supply hose). If coolant return hose is much cooler
than the supply hose, locate and repair engine cool-
ant flow obstruction in heater system.
Fig. 12 Evaporator Probe Harness Connector
1 ± PIN #3
2 ± PIN #2
3 ± PIN #1
Fig. 13 Expansion Valve & Low Pressure Cut-Off
Switch - Typical
1 ± EXPANSION VALVE
2 ± LOW PRESSURE CUT OFF SWITCH
3 ± SUCTION LINE
4 ± CONTROL HEAD
TEMPERATURE REFERENCE CHART
Ambient Temp. Minimum
FloorOutlet
Temp.
Celsius Fahrenheit Celsius Fahrenheit
15.5É 60É 62.2É 144É
21.1É 70É 63.8É 147É
26.6É 80É 65.5É 150É
32.2É 90É 67.2É 153É
PLHEATING AND AIR CONDITIONING 24 - 13
DIAGNOSIS AND TESTING (Continued)

POSSIBLE LOCATIONS OR CAUSE OF
OBSTRUCTED COOLANT FLOW
(1) Pinched or kinked heater hoses.
(2) Improper heater hose routing.
(3) Plugged heater hoses or supply and return
ports at cooling system connections, refer to Group 7,
Cooling System.
(4) Plugged heater core.
(5) Air locked heater core.
(6) If coolant flow is verified and outlet tempera-
ture is insufficient, a mechanical problem may exist.
POSSIBLE LOCATION OR CAUSE OF INSUFFICIENT
HEAT
(1) Obstructed cowl air intake.
(2) Obstructed heater system outlets.
(3) Blend-air door not functioning properly.
TEMPERATURE CONTROL
If temperature cannot be adjusted with the TEMP
lever on the control panel, the following could require
service:
(1) Blend-air door binding.
(2) Faulty blend-air door cable.
(3) Improper engine coolant temperature.
(4) Faulty Instrument Panel Control.
LOW PRESSURE CUT OFF SWITCH
The work area must not be below 21ÉC (70ÉF) to
test the compressor clutch circuit.
(1) With gear selector in park or neutral and park
brake set, start engine and allow to idle.
(2) Raise hood and disconnect low pressure cut off
switch connector boot.
(3) Using a suitable jumper wire, jump across the
terminals inside wire connector boot.
(4) If the compressor clutch does not engage, the
cycling clutch switch, wiring, relay, or fuse can be
defective. Refer to Group 8W, Wiring Diagrams.
(5) If clutch engages, connect manifold gauge set.
Read low pressure gauge. At pressure above 97 kPa
(14 psi) and above, low pressure out off switch will
complete the clutch circuit. If the low pressure gauge
reads below 140 kPa (20 psi), the system is low on
refrigerant charge or empty due to a leak. Refer to
Service Procedures, System Leak Checking in this
section.
(6) Install connector boot on switch and repeat
Step 3. If the clutch does not engage, replace the low
pressure cut off switch.
SYSTEM CHARGE LEVEL TEST
The procedure below should be used to check
and/or fill the refrigerant charge in the air condition-
ing system.
WARNING: AVOID BREATHING A/C REFRIGERANT
AND LUBRICANT VAPOR OR MIST. EXPOSURE MAY
IRRITATE EYES, NOSE AND THROAT. USE ONLY
APPROVED SERVICE EQUIPMENT MEETING SAE
REQUIREMENTS TO DISCHARGE R-134a SYSTEM.
IF ACCIDENTAL SYSTEM DISCHARGE OCCURS,
VENTILATE WORK AREA BEFORE RESUMING SER-
VICE.
R-134a SERVICE EQUIPMENT OR VEHICLE A/C
SYSTEM SHOULD NOT BE PRESSURE TESTED OR
LEAK TESTED WITH COMPRESSED AIR. MIXTURE
OF AIR and R-134a CAN BE COMBUSTIBLE AT ELE-
VATED PRESSURES. THESE MIXTURES ARE
POTENTIALLY DANGEROUS AND MAY RESULT IN
FIRE OR EXPLOSION CAUSING INJURY OR PROP-
ERTY DAMAGE.
NOTE: The maximum amount of R-134a refrigerant
that the air conditioning system holds is 765 grams
(27 oz. or 1.69 lbs.)
It is recommended to use the gauges or reclaim/re-
cycle equipment.
(1) Use a manifold gauge and check the liquid line
pressure.
(2) Attach a clamp-on thermocouple (P. S. E.
66-324-0014 or 80PK-1A) or equivalent to the liquid
line near the filter/drier.
(3) The vehicle must be in the following modes:
²Automatic transaxle in park or manual tran-
saxle in neutral.
²Engine at idle
²A/C controls set to outside air
²Panel mode
²A/C ON full cool
²Blower motor ON high speed
²Vehicle windows closed
(4) Operate system for a couple of minutes to allow
the system to stabilize.
(5) Observe filter/drier pressure and Liquid line
temperature. Using the Charge Determination Chart
(Fig. 14) determine where the system is currently
operating. If the system is not in the proper range,
reclaim all the refrigerant and recharge per A/C
label.
24 - 14 HEATING AND AIR CONDITIONINGPL
DIAGNOSIS AND TESTING (Continued)

HEATER-A/C VACUUM SYSTEM DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
NO FORCED AIR IN
HEAT POSITION1. Vacuum line pinched or
leaking.
2. Faulty heat defroster or
mode door.
3. Faulty selector switch.
4. Vacuum check valve.1. Locate and repair vacuum leak or pinched line.
2. Test actuators and door operation. Repair as
necassary.
3. Test selector switch and replace if necessary.
4. Test check valve and replace if necessary.
NO FORCED AIR IN
PANEL POSITION1. Vacuum line pinched or
leaking.
2. Faulty mode door.
3. Faulty selector switch.
4. Vacuum check valve.1. Locate and repair vacuum leak or pinched line.
2. Test actuator and door operation. Repair as
necessary.
3. Test selector switch and replace if necessary.
4. Test check valve and replace if necessary.
NO FORCED AIR IN
DEFROST POSITION1. Vacuum line pinched or
leaking.
2. Faulty heat, defroster, or
mode door.
3. Faulty selector switch.
4. Vacuum check valve.1. Locate and repair vacuum leak or pinched line.
2. Test actuators and door operation. Repair as
necessary.
3. Test selector switch and replace if necessary.
4. Test check valve and replace if necessary.
ONE-WAY CHECK VALVE
(1) Disconnect the heater-A/C vacuum supply
(Black) tube in the engine compartment. This tube
passes through an opening in the dash panel.
(2) Remove the one-way vacuum check valve. The
valve is located on the (Black) vacuum supply hose at
the brake power booster.
(3) Connect the test set vacuum supply hose to the
heater side of the valve. When connected to this side
of the check valve, no vacuum should pass and the
test set gauge should return to the 27 kPa (8 in. Hg.)
setting. If OK, go to step Step 4. If not OK, replace
the faulty valve.
(4) Connect the test set vacuum supply hose to the
engine vacuum side of the valve. When connected to
this side of the check valve, vacuum should flow
through the valve without restriction. If not OK,
replace the faulty valve.
HEATER-A/C CONTROLS
The operation of the Circulation door can be
viewed by removing the blower motor and looking up
into the unit inlet. See Blower Motor Wheel and
Assembly removal and installation in this section for
service procedures.
(1) Connect the test set vacuum probe to the heat-
er-A/C vacuum supply (Black) hose in the engine
compartment. Position the test set gauge so that it
can be viewed from the passenger compartment.
(2) Start with the Mode control in the Panel posi-
tion and the Circulation control in the Outside-air
position.
(3) Move the Circulation control to the Recircula-
tion position (the Circulation door should move intothe Recirculation position). After a short pause move
the Mode control to the Defrost position (the Circula-
tion door should move to the Outside-air position).
The test gauge should return to the calibrated set-
ting of 27 kPa (8 in. Hg.) after each selection is
made. If the gauge cannot achieve the calibrated set-
ting, the vacuum circuit or a component has a leak.
(4) If the gauge achieves the calibrated setting but
the door does not move, there is either a pinched vac-
uum line or a failed actuator.
LOCATING VACUUM LEAKS
(1) Connect the test vacuum probe to the vehicles
(Black) supply hose. Position the vacuum test gauge
so it can be viewed from the passenger compartment.
(2) Place the Mode in the Panel position and the
Circulation control in the Recirculation position.
(3) Remove the center instrument panel bezel.
(4) Remove the center vent duct.
(5) Remove and block the Supply (Black) vacuum
line at the control. The test gauge should return to
the calibrated setting of 27 kPa (8 in. Hg). If not,
there is a leak in the Supply line.
(6) If there is no leak in the Supply line, reconnect
it to the Control and remove the Actuator Feed (Red)
line from the Control. Block the vacuum connection
on the Control from where the line was removed. The
test gauge should return to the calibrated setting of
27 kPa (8 in. Hg.). If not, there is a leak in the Con-
trol.
(7) If there is no leak in the Supply line or the
Control, reconnect the Actuator Feed (Red) line to the
control. Remove and block the Actuator Feed (Red)
line at the Actuator. The actuator vacuum port is
accessible behind and above the Glove Box. The test
24 - 16 HEATING AND AIR CONDITIONINGPL
DIAGNOSIS AND TESTING (Continued)