clutch DODGE NEON 2000 Service Repair Manual

NOTE: Comprehensive component monitors are
continuous. Therefore, enabling conditions do not
apply.
Input RationalityÐWhile input signals to the
PCM are constantly being monitored for electrical
opens and shorts, they are also tested for rationality.
This means that the input signal is compared against
other inputs and information to see if it makes sense
under the current conditions.
PCM sensor inputs that are checked for rationality
include:
²Manifold Absolute Pressure (MAP) Sensor
²Oxygen Sensor (O2S)
²Engine Coolant Temperature (ECT) Sensor
²Camshaft Position (CMP) Sensor
²Vehicle Speed Sensor
²Crankshaft Position (CKP) Sensor
²Intake Air Temperature (IAT) Sensor
²Throttle Position (TPS) Sensor
²Ambient/Battery Temperature Sensors
²Power Steering Switch
²Oxygen Sensor Heater
²Engine Controller
²Brake Switch
²Leak Detection Pump Switch
²P/N Switch
²Trans Controls
Output FunctionalityÐPCM outputs are tested
for functionality in addition to testing for opens and
shorts. When the PCM provides a voltage to an out-
put component, it can verify that the command was
carried out by monitoring specific input signals for
expected changes. For example, when the PCM com-
mands the Idle Air Control (IAC) Motor to a specific
position under certain operating conditions, it expects
to see a specific (target) idle speed (RPM). If it does
not, it stores a DTC.
PCM outputs monitored for functionality include:
²Fuel Injectors
²Ignition Coils
²Torque Converter Clutch Solenoid
²Idle Air Control
²Purge Solenoid
²EGR Solenoid
²LDP Solenoid
²Radiator Fan Control
²Trans Controls
OXYGEN SENSOR (O2S) MONITOR
DESCRIPTIONÐEffective control of exhaust
emissions is achieved by an oxygen feedback system.
The most important element of the feedback system
is the O2S. The O2S is located in the exhaust path.
Once it reaches operating temperature 300É to 350ÉC
(572É to 662ÉF), the sensor generates a voltage that
is inversely proportional to the amount of oxygen inthe exhaust. When there is a large amount of oxygen
in the exhaust caused by a lean condition, the sensor
produces a low voltage, below 450 mV. When the oxy-
gen content is lower, caused by a rich condition, the
sensor produces a higher voltage, above 450mV.
The information obtained by the sensor is used to
calculate the fuel injector pulse width. This main-
tains a 14.7 to 1 air fuel (A/F) ratio. At this mixture
ratio, the catalyst works best to remove hydrocarbons
(HC), carbon monoxide (CO) and nitrous oxide (NOx)
from the exhaust.
The O2S is also the main sensing element for the
EGR, Catalyst and Fuel Monitors.
The O2S may fail in any or all of the following
manners:
²Slow response rate (Big Slope)
²Reduced output voltage (Half Cycle)
²Heater Performance
Slow Response Rate (Big Slope)ÐResponse
rate is the time required for the sensor to switch
from lean to rich signal output once it is exposed to a
richer than optimum A/F mixture or vice versa. As
the PCM adjusts the air/fuel ratio, the sensor must
be able to rapidly detect the change. As the sensor
ages, it could take longer to detect the changes in the
oxygen content of the exhaust gas. The rate of
change that an oxygen sensor experiences is called
'Big Slope'. The PCM checks the oxygen sensor volt-
age in increments of a few milliseconds.
Reduced Output Voltage (Half Cycle)ÐThe
output voltage of the O2S ranges from 0 to 1 volt. A
good sensor can easily generate any output voltage in
this range as it is exposed to different concentrations
of oxygen. To detect a shift in the A/F mixture (lean
or rich), the output voltage has to change beyond a
threshold value. A malfunctioning sensor could have
difficulty changing beyond the threshold value. Each
time the voltage signal surpasses the threshold, a
counter is incremented by one. This is called the Half
Cycle Counter.
Heater PerformanceÐThe heater is tested by a
separate monitor. Refer to the Oxygen Sensor Heater
Monitor.
OPERATIONÐAs the Oxygen Sensor signal
switches, the PCM monitors the half cycle and big
slope signals from the oxygen sensor. If during the
test neither counter reaches a predetermined value, a
malfunction is entered and a Freeze Frame is stored.
Only one counter reaching its predetermined value is
needed for the monitor to pass.
The Oxygen Sensor Monitor is a two trip monitor
that is tested only once per trip. When the Oxygen
Sensor fails the test in two consecutive trips, the
MIL is illuminated and a DTC is set. The MIL is
extinguished when the Oxygen Sensor monitor
passes in three consecutive trips. The DTC is erased
25 - 20 EMISSION CONTROL SYSTEMSPL
DESCRIPTION AND OPERATION (Continued)

from memory after 40 consecutive warm-up cycles
without test failure.
Enabling ConditionsÐThe following conditions
must typically be met for the PCM to run the oxygen
sensor monitor:
²Battery voltage
²Engine temperature
²Engine run time
²Engine run time at a predetermined speed
²Engine run time at a predetermined speed and
throttle opening
²Transmission in gear (automatic only)
²Fuel system in Closed Loop
²Long Term Adaptive (within parameters)
²Power Steering Switch in low PSI (no load)
²Engine at idle
²Fuel level above 15%
²Ambient air temperature
²Barometric pressure
²Engine RPM within acceptable range of desired
idle
²Closed throttle speed
Pending ConditionsÐThe Task Manager typi-
cally does not run the Oxygen Sensor Monitor if over-
lapping monitors are running or the MIL is
illuminated for any of the following:
²Misfire Monitor
²Front Oxygen Sensor and Heater Monitor
²MAP Sensor
²Vehicle Speed Sensor
²Engine Coolant Temperature Sensor
²Throttle Position Sensor
²Engine Controller Self Test Faults
²Cam or Crank Sensor
²Injector and Coil
²Idle Air Control Motor
²EVAP Electrical
²EGR Solenoid Electrical
²Intake Air Temperature
²5 Volt Feed
ConflictÐThe Task Manager does not run the
Oxygen Sensor Monitor if any of the following condi-
tions are present:
²A/C ON (A/C clutch cycling temporarily sus-
pends monitor)
²Purge flow in progress
SuspendÐThe Task Manager suspends maturing
a fault for the Oxygen Sensor Monitor if an of the fol-
lowing are present:
²Oxygen Sensor Heater Monitor, Priority 1
²Misfire Monitor, Priority 2
OXYGEN SENSOR HEATER MONITOR
DESCRIPTIONÐIf there is an oxygen sensor
(O2S) DTC as well as a O2S heater DTC, the O2S
fault MUST be repaired first. After the O2S fault isrepaired, verify that the heater circuit is operating
correctly.
The voltage readings taken from the O2S are very
temperature sensitive. The readings are not accurate
below 300ÉC. Heating of the O2S is done to allow the
engine controller to shift to closed loop control as
soon as possible. The heating element used to heat
the O2S must be tested to ensure that it is heating
the sensor properly.
The heater element itself is not tested. The sensor
output is used to test the heater by isolating the
effect of the heater element on the O2S output volt-
age from the other effects. The resistance is normally
between 100 ohms and 4.5 megaohms. When oxygen
sensor temperature increases, the resistance in the
internal circuit decreases. The PCM sends a 5 volts
biased signal through the oxygen sensors to ground
this monitoring circuit. As the temperature increases,
resistance decreases and the PCM detects a lower
voltage at the reference signal. Inversely, as the tem-
perature decreases, the resistance increases and the
PCM detects a higher voltage at the reference signal.
an The O2S circuit is monitored for a drop in voltage.
OPERATIONÐThe Oxygen Sensor Heater Moni-
tor begins after the ignition has been turned OFF
and the O2 sensors have cooled. The PCM sends a 5
volt bias to the oxygen sensor every 1.6 seconds. The
PCM keeps it biased for 35 ms each time. As the sen-
sor cools down, the resistance increases and the PCM
reads the increase in voltage. Once voltage has
increased to a predetermined amount, higher than
when the test started, the oxygen sensor is cool
enough to test heater operation.
When the oxygen sensor is cool enough, the PCM
energizes the ASD relay. Voltage to the O2 sensor
begins to increase the temperature. As the sensor
temperature increases, the internal resistance
decreases. The PCM continues biasing the 5 volt sig-
nal to the sensor. Each time the signal is biased, the
PCM reads a voltage decrease. When the PCM
detects a voltage decrease of a predetermined value
for several biased pulses, the test passes.
The heater elements are tested each time the
engine is turned OFF if all the enabling conditions
are met. If the monitor fails, the PCM stores a
maturing fault and a Freeze Frame is entered. If two
consecutive tests fail, a DTC is stored. Because the
ignition is OFF, the MIL is illuminated at the begin-
ning of the next key cycle.
Enabling ConditionsÐThe following conditions
must be met for the PCM to run the oxygen sensor
heater test:
²Engine run time of at least 5.1 minutes
²Key OFF power down
²Battery voltage of at least 10 volts
²Sufficient Oxygen Sensor cool down
PLEMISSION CONTROL SYSTEMS 25 - 21
DESCRIPTION AND OPERATION (Continued)

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

GENERAL INFORMATION
A/C APPLICATION TABLE
Item Description Notes
Vehicle PL Neon
System expansion valve
Total Refrigerant
CapacityR134a 765 grams / 27 oz / 1.69 lbs
Total Oil Capacity ND-8 PAG oil 180 ml / 6.10 oz
Compressor Nippondenso 10S17
Freeze-up Control Fin sensor-3 wire input to PCM, evaporator mounted, cycles
clutch off below 34É F, cycles back on
above 45É F
Low psi Control opens < 14 psi, resets > 38 psi expansion valve mounted
High psi Control opens > 470 psi, resets < 370 - 330 psi compressor mounted switch
Control head manual type
Mode Door cable
Blend Air Door cable
Fresh/Recirc door vacuum actuator
Blower Motor control head switched resistor block
Cooling Fan variable speed PCM controlled ISO solid state fan relay
Clutch
Control relay PCM
Draw 2.5 amps @ 12V60.5V @ 70É F
Gap 0.014º - 0.0269
DRB IIIT
Reads TPS, RPM, A/C switch test, fin sensor
A/C & fan relays
Actuators fan & clutch relays
HEATER AND AIR CONDITIONING CONTROL
Both the heater-only and heater-A/C systems use a
combination of, electrical, cable, and vacuum con-
trols. These controls provide the vehicle operator
with a number of setting options to help control the
climate and comfort within the vehicle. Refer to the
owner's manual in the vehicle glove box for more
information on the features, use, and suggested oper-
ation of these controls.
The heater-only or heater-A/C control panel is located
to the right of the instrument cluster on the instrument
panel. The control panel contains rotary-type knobs.
There is a blower motor speed switch, mode control
switch, temperature control, and airflow control.
The heater-only or heater-A/C control panel cannot
be repaired. If faulty or damaged, the entire unit
must be replaced. The control knobs and the illumi-
nation lamps are available for service replacement.
HEATER AND AIR CONDITIONING
All vehicles are equipped with a common heater-
A/C housing assembly (Fig. 1). The system combines
air conditioning, heating, and ventilating capabilities
in a single unit housing mounted under the instru-
ment panel. On heater-only systems, the evaporator
coil is omitted from the housing and replaced with an
air restrictor plate.
Outside air enters the vehicle through the cowl top
opening at the base of the windshield, and passes
through a plenum chamber to the heater-A/C system
blower housing. Air flow velocity can then be
adjusted with the blower motor speed selector switch
on the heater-A/C control panel. The air intake open-
ings must be kept free of snow, ice, leaves, and other
obstructions for the heater-A/C system to receive a
sufficient volume of outside air.
24 - 2 HEATING AND AIR CONDITIONINGPL

It is also important to keep the air intake openings
clear of debris because leaf particles and other debris
that is small enough to pass through the cowl ple-
num screen can accumulate within the heater-A/C
housing. The closed, warm, damp and dark environ-
ment created within the heater-A/C housing is ideal
for the growth of certain molds, mildews and other
fungi. Any accumulation of decaying plant matter
provides an additional food source for fungal spores,
which enter the housing with the fresh air. Excess
debris, as well as objectionable odors created by
decaying plant matter and growing fungi can be dis-
charged into the passenger compartment during
heater-A/C system operation.
The heater and optional air conditioner are blend-
air type systems. In a blend-air system, a blend-air
door controls the amount of unconditioned air (or
cooled air from the evaporator on models with air
conditioning) that is allowed to flow through, or
around, the heater core. A temperature control knob
on the heater-A/C control panel determines the dis-
charge air temperature by moving a cable, which
operates the blend-air door. This allows an almost
immediate manual control of the output air tempera-
ture of the system.
The mode control knob on the heater-only or heat-
er-A/C control panel is used to direct the conditioned
air to the selected system outlets. The mode control
switch uses a cable to control the mode door, while
the recirculation air door is operated by a vacuum
actuator motor.On air conditioned vehicles, the outside air intake
can be shut off by selecting the recirculation mode
(Recirc) with the mode control knob. This will oper-
ate a vacuum actuated recirculating air 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 an evaporator probe to maintain minimum
evaporator temperature and prevent evaporator
freezing, and cycles the compressor clutch.
INTRODUCTION
Both the heater and the heater/air conditioning
systems share many of the same functioning compo-
nents. This group will deal with both systems
together when component function is common, and
separately when they are not.
For proper operation of the instrument panel con-
trols, refer to the Owner's Manual provided with the
vehicle.
To service the heater core or evaporator, the unit
housing must be removed from the vehicle (Fig. 2).Fig. 1 Common Blend-Air HVAC (Heating,
Ventilation, Air Conditioning) System - Typical
1 ± TEMPERATURE BLEND/AIR DOOR
2 ± EVAPORATOR CORE
3 ± BLOWER
4 ± PANEL DEFROST DOOR
5 ± HEAT DEFROST DOOR
6 ± HEATER CORE
7 ± RECIRCULATING AIR DOOR
Fig. 2 HVAC Unit Housing
1 ± AIR DISTRIBUTION
2 ± RECIRCULATION DOOR VACUUM ACTUATOR
3 ± AIR INLET
4 ± BLOWER MOTOR
5 ± EVAPORATOR PROBE CONNECTOR
6 ± CONTROL CABLES
7 ± VACUUM HARNESS
PLHEATING AND AIR CONDITIONING 24 - 3
GENERAL INFORMATION (Continued)

A/C SERVICE PORT VALVE CORES
The A/C service port valve cores are serviceable
items (Fig. 4). The high side valve is located on the
filter-drier, and the low side valve is situated on the
suction line, near the washer fluid reservoir filler.
BLOWER MOTOR RESISTOR
The blower motor resistor is located in the cowl, at
the base of the windshield (Fig. 5). There are two dif-
ferent resistor blocks depending on whether the vehi-
cle is equipped with A/C or not. The blower motor
resistors will get hot when in use (Fig. 6). Do not
touch resistor block if the blower motor has been
running.
COMPRESSOR
The compressor used on this vehicle is a Nippon-
denso 10S17. This compressor uses an aluminum
swash plate, teflon coated pistons and aluminum
sleeveless cylinder walls.
NOISE
Excessive noise that occurs when the air condition-
ing is being used may be caused by:
²Loose bolts
²Mounting brackets
²Loose compressor clutch
²Excessive high refrigerant operating pressureVerify the following before compressor repair is
performed:
(1) Compressor drive belt condition
(2) Proper refrigerant charge
(3) Thermal expansion valve (TXV) operating cor-
rectly
(4) Head pressure is normal
Fig. 4 A/C Service Port Valves
1 ± A/C SERVICE PORTS
2 ± FILTER/DRIER
Fig. 5 Blower Motor Resistor Block
1 ± RESISTOR BLOCK
2 ± ELECTRICAL CONNECTOR
Fig. 6 Blower Motor Resistors
1 ± RESISTOR BLOCK
2 ± RESISTORS
PLHEATING AND AIR CONDITIONING 24 - 5
DESCRIPTION AND OPERATION (Continued)

COMPRESSOR FRONT SHAFT SEAL
The compressor front shaft seal is not serviceable.
If a leak is detected at the shaft seal, the compressor
must be replaced as a unit.
CONDENSATION DRAIN TUBE
Condensation that accumulates in the evaporator
housing is drained from a tube through the dash and
on to the ground. This tube must be kept open to
prevent condensate water from collecting in the bot-
tom of the housing.
The tapered end of the drain tube is designed to
keep contaminants from entering the heater A/C unit
housing. If the tube is pinched or blocked, condensate
cannot drain, causing water to back up and spill into
the passenger compartment. It is normal to see con-
densate drainage below the vehicle. If the tube is
damaged, it should be replaced.
ENGINE COOLING SYSTEM REQUIREMENTS
To maintain ample temperature levels from the
heating-A/C system, the cooling system must be in
proper working order. Refer to Group 0, Lubrication
and Maintenance or Group 7, Cooling System of this
manual.
The use of a bug screen is not recommended. Any
obstructions forward of the condenser can reduce the
effectiveness of the air conditioning system.
EVAPORATOR PROBE
The evaporator probe can be replaced without hav-
ing to remove the unit housing from the vehicle.
The evaporator probe is located in the unit housing
and placed in the evaporator fins. The probe prevents
evaporator freeze-up. This is done by cycling the com-
pressor clutch OFF when evaporator temperature
drops below freeze point. It cycles ON when the
evaporator temperature rises above freeze point. The
evaporator probe uses a thermistor probe in a capil-
lary tube. The tube is inserted between the evapora-
tor fins in the heater-A/C unit housing.
HANDLING TUBING AND FITTINGS
Kinks in the refrigerant tubing or sharp bends in
the refrigerant hose lines will greatly reduce the
capacity of the entire system. High pressures are pro-
duced in the system when it is operating. Extreme
care must be exercised to make sure that all connec-
tions are pressure tight. Dirt and moisture can enter
the system when it is opened for repair or replace-
ment of lines or components. The refrigerant oil will
absorb moisture readily out of the air. This moisture
will convert into acids within a closed system.CAUTION: The system must be completely empty
before opening any fitting or connection in the
refrigeration system. Open fittings with caution
even after the system has been emptied. If any
pressure is noticed as a fitting is loosened,
retighten fitting and evacuate the system again.
A good rule for the flexible hose lines is to keep
the radius of all bends at least 10 times the diame-
ter of the hose. Sharper bends will reduce the flow
of refrigerant. The flexible hose lines should be
routed so they are at least 3 inches (80 mm) from
the exhaust manifold. Inspect all flexible hose lines
to make sure they are in good condition and prop-
erly routed.
The use of correct wrenches when making con-
nections is very important. Improper wrenches or
improper use of wrenches can damage the fittings.
The internal parts of the A/C system will remain
stable as long as moisture-free refrigerant and
refrigerant oil is used. Abnormal amounts of dirt,
moisture or air can upset the chemical stability.
This may cause operational troubles or even seri-
ous damage if present in more than very small
quantities.
When opening a refrigeration system, have every-
thing you will need to repair the system ready. This
will minimize the amount of time the system must
be opened. Cap or plug all lines and fittings as
soon as they are opened. This will help prevent the
entrance of dirt and moisture. All new lines and
components should be capped or sealed until they
are ready to be used.
All tools, including the refrigerant dispensing
manifold, the manifold gauge set, and test hoses
should be kept clean and dry.
HIGH PRESSURE CUT OUT SWITCH
The high pressure cut out switch is located on the
rear of the compressor (Fig. 7). It turns off the com-
pressor if the system pressure exceeds 3240 kPa (470
psi).
LOW PRESSURE CUT OFF SWITCH
The Low Pressure Cut Off Switch (Fig. 8) monitors
the refrigerant gas pressure on the suction side of
the system. The low pressure cut off switch is located
on the expansion valve. The low pressure cut off
switch turns off voltage to the compressor clutch coil
when refrigerant gas pressure drops to levels that
could damage the compressor. The low pressure cut
out switch is a sealed factory calibrated unit. It must
be replaced if defective.
24 - 6 HEATING AND AIR CONDITIONINGPL
DESCRIPTION AND OPERATION (Continued)

Normally, vacuum is supplied to the actuator by
placing the Circulation control knob in the Recircula-
tion position. The Mode and the circulation control
are mechanically interlocked so the circulation con-
trol cannot be placed in the RECIRC position if the
mode control is at or between the mix and defrost
positions. Vacuum is supplied to the actuator only
when circulation control is at the RECIRC position.
If the circulation control is between the outside air
position and RECIRC position the system will be in
outside air. If the circulation control is in the
RECIRC position and the mode control is moved from
the floor to the defrost positions, the circulation con-
trol will move from the RECIRC position, to the out-
side air position beginning at the mix position. This
is to prevent window fogging.
DIAGNOSIS AND TESTING
A/C PERFORMANCE TEST
The air conditioning system is designed to remove
heat and humidity from the air entering the passen-
ger compartment. The evaporator, located in the
heater A/C unit, is cooled to temperatures near the
freezing point. As warm damp air passes over the
fins in the evaporator, moisture in the air condenses
to water, dehumidifying the air. Condensation on the
evaporator fins reduces the evaporators ability to
absorb heat. During periods of high heat and humid-
ity, an air conditioning system will be less effective.
With the instrument control set to RECIRC, only air
from the passenger compartment passes through theevaporator. As the passenger compartment air dehu-
midifies, A/C performance levels rise.
PERFORMANCE TEST PROCEDURE
Review Safety Precautions and Warnings in this
group before proceeding with this procedure. Air tem-
perature in test room and on vehicle must be 21É C
(70ÉF) minimum for this test.
NOTE: When connecting the service equipment
coupling to the line fitting, verify that the valve of
the coupling is fully closed. This will reduce the
amount of effort required to make the connection.
(1) Connect a tachometer and manifold gauge set.
(2) Set control to A/C, RECIRC, and PANEL, tem-
perature lever on full cool and blower on high.
(3) Start engine and hold at 1000 rpm with A/C
clutch engaged.
(4) Engine should be warmed up with doors and
windows closed.
(5) Insert a thermometer in the left center A/C
outlet and operate the engine for five minutes. The
A/C clutch may cycle depending on ambient condi-
tions.
(6) With the A/C clutch engaged, compare the dis-
charge air temperature to the A/C Performance Tem-
peratures chart.
(7) If the discharge air temperature fails to meet
the specifications in the performance temperature
chart. Refer to the Refrigerant Service Procedures for
further diagnosis.
A/C PERFORMANCE TEMPERATURES
Ambient Temperature 21ÉC (70ÉF) 26.5ÉC (80ÉF) 32ÉC (90ÉF) 37ÉC (100ÉF) 43ÉC (110ÉF)
Air Temperature at Left
Center Panel Outlet1-8ÉC
(34-46ÉF)3-9ÉC
(37-49ÉF)4-10ÉC
(39-50ÉF)6-11ÉC
(43-52ÉF)7-18ÉC
(45-65ÉF)
Compressor Discharge
Pressure After the Filter
Drier1034-1724 kPa
(150-250 PSI)1517-2275 kPa
(220-330 PSI1999-2620
kPa (290-380
PSI)2068-2965
kPa (300-430
PSI)2275-3421 kPa
(330-496 PSI)
Evaporator Suction
Pressure103-207 kPa
(15-30 PSI)117-221 kPa
(17-32 PSI)138-241 kpa
(20-35 PSI)172-269 kpa
(25-39 PSI)207-345 kPa
(30-50 PSI)
BLOWER MOTOR ELECTRICAL DIAGNOSIS
Refer to the Blower Motor Electrical System Diag-
nosis chart (Fig. 11) in this section. Also refer to
Group 8W, Wiring Diagrams for more information.
PLHEATING AND AIR CONDITIONING 24 - 9
DESCRIPTION AND OPERATION (Continued)

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)

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)