heating DODGE NEON 1999 Service Service Manual

(2) If previous probe was removed from top hole,
use a small plastic stick and make a new hole. Make
the hole 1/4 inch above or below the original hole in
the evaporator core.
(3) Insert new probe into hole between evaporator
fins.
(4) Reinstall rubber grommet into evaporator
probe access hole.
EXPANSION VALVE
WARNING: THE REFRIGERATION SYSTEM MUST
BE COMPLETELY EMPTY BEFORE PROCEEDING
WITH THIS OPERATION.
REMOVAL
(1) Remove the boot-type wire connector from the
pressure cut-off switch.
(2) Remove the center bolt of refrigerant line
plumbing sealing plate (Fig. 31).
(3) Carefully pull the refrigerant line-sealing plate
assembly from the expansion valve towards front of
vehicle. Do not scratch the expansion valve sealing
surfaces with pilot tubes.
(4) Cover the openings on A/C line-sealing plate
assembly to prevent contamination.
(5) Remove two screws securing the expansion
valve to the evaporator sealing plate.
(6) Carefully remove valve.
INSTALLATION
(1) Remove and replace the aluminum gasket on
the evaporator sealing plate.
(2) Carefully hold the expansion valve to the evap-
orator sealing plate so not to scratch the sealing sur-
face. Install two screws and tighten to 1163 N´m
(100630 in. lbs.).
(3) Remove and replace the aluminum gasket on
the refrigerant line- sealing plate assembly.(4) Carefully hold the refrigerant line-sealing plate
assembly to the expansion valve. Install bolt and
tighten to 2363 N´m (200630 in. lbs.).
(5) Connect wires to low pressure cut-off switch.
(6) Evacuate and recharge system.
(7) After expansion valve is installed, system is
charged, and leaks have been checked, repeat A/C
performance check.
A/C FILTER/DRIER
The filter/drier is mounted in a rubber grommet on
the right side of the engine compartment. The refrig-
erant must be recovered from the A/C system before
replacing the filter/drier assembly.
WARNING: THE REFRIGERATION SYSTEM MUST
BE COMPLETELY RECOVERED BEFORE PRO-
CEEDING WITH THIS OPERATION.
REMOVAL
(1) Disconnect liquid line from filter/drier.
(2) Disconnect liquid line on suction line assembly
from filter/drier.
(3) Pull filter/drier out of rubber grommet.
INSTALLATION
For installation, reverse the above procedures.
HIGH PRESSURE CUT OUT SWITCH
WARNING: THE REFRIGERANT MUST BE
REMOVED FROM THE SYSTEM BEFORE REMOV-
ING THE HIGH PRESSURE CUT OUT SWITCH.
REMOVAL
(1) Disconnect wiring connector at the switch (Fig.
32).
(2) Remove internal snap ring.
Fig. 30 Evaporator Probe LocationFig. 31 Expansion Valve
PLHEATING AND AIR CONDITIONING 24 - 23
REMOVAL AND INSTALLATION (Continued)

(3) Pull switch out of manifold.
INSTALLATION
For installation, reverse the above procedures.
HIGH PRESSURE RELIEF VALVE
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.
REMOVAL
(1) Using a R-134a refrigerant recovery machine,
remove the refrigerant from A/C system.
(2) Rotate the high pressure relief valve counter-
clockwise and separate relief valve from the vehicle
(Fig. 32).
INSTALLATION
For installation, reverse the above procedures
using a new O-ring seal. Evacuate and charge the
refrigerant system.
HEATER CORE
Refer to Air Distribution Recondition of this section
for heater core removal procedure.
HEATER HOSES
CAUTION: When removing hoses from heater core
inlet or outlet nipples DO NOT exert excess pres-
sure. The heater core may become damaged and
leak engine coolant.
NOTE: Review Cooling System Precautions before
proceeding with this operation.
REMOVAL
(1) Drain engine cooling system. Refer to Group 7,
Cooling System.
(2) Remove clamp at end of heater hose to be
removed.
(3) RHD vehicles, heater hoses at the heater core
connection have quick connects (Fig. 33). The quick
connect consist of two pieces; a quick connect and
insert. The quick connect is removed by compressing
the insert with a pliers, pull quick connect free of
insert/nipple. Carefully compressed insert pulling the
quick connect from connector nipple. The insert will
remain on the connector nipple as the quick connect
is removed.
(4) Remove the heater hose clamp from the heater
hose at the block and remove hose.
INSTALLATION
NOTE: The insert should be remove from the con-
nector nipple and place it in side of the quick con-
nect.
For installation, reverse the above procedures.
Fig. 33 Heater Hose Quick Connect
Fig. 32 High Pressure Relief Valve Location
24 - 24 HEATING AND AIR CONDITIONINGPL
REMOVAL AND INSTALLATION (Continued)

LIQUID LINE
WARNING: THE REFRIGERATION SYSTEM MUST
BE COMPLETELY EMPTY BEFORE PROCEEDING
WITH THIS OPERATION.
REMOVAL
(1) Using a R-134a refrigerant recovery machine,
remove the refrigerant from A/C system.
(2) Disconnect liquid line at drier.
(3) Disconnect liquid line at condenser.
INSTALLATION
For installation, reverse the above procedures.
LOW PRESSURE CUT OFF SWITCH
WARNING: THE REFRIGERATION SYSTEM MUST
BE COMPLETELY RECOVERED BEFORE PRO-
CEEDING WITH THIS OPERATION. REFER TO
REFRIGERANT RECOVERY SECTION.
REMOVAL
(1) Disconnect the boot like wire connector at the
cut off switch.
(2) Using a sender unit removal socket, remove the
switch from the expansion valve (Fig. 34).
INSTALLATION
NOTE: Verify the O-ring condition on the replace-
ment switch.
For installation, reverse the above procedures.
Evacuate and charge the system.
MODE CONTROL CABLE
The Mode Control Cable can be removed and
installed without having to remove the instrument
panel from the vehicle.
REMOVAL
(1) Remove instrument panel upper cowl panel.
(2) Remove right side upper instrument panel
bezel (Fig. 35).
(3) Remove center vent duct (Fig. 36).
(4) Remove upper defrost duct (Fig. 37).
(5) Remove inner defrost duct (Fig. 38).
(6) Disconnect cable at heater unit.
(7) Disconnect cable at control panel.
(8) Remove cable from vehicle.
INSTALLATION
For installation, reverse the above procedures,
adjust cable and test. Refer to Mode Control Cable
Adjustment at the end of this section.
Fig. 34 Low Pressure Cut-Off Switch and Expansion
Valve ± Typical
Fig. 35 Bezel Removal
Fig. 36 Instrument Panel Center Vent
PLHEATING AND AIR CONDITIONING 24 - 25
REMOVAL AND INSTALLATION (Continued)

RECIRCULATION DOOR ACTUATOR
The recirculation door actuator is a vacuum con-
trolled actuator used to control movement of the
recirculation door in air conditioned equipped vehi-
cles.
The instrument panel must be removed from the
vehicle to gain access to the recirculation door actua-
tor.
REMOVAL
(1) Remove instrument panel from vehicle. Refer
to Group 8E, Instrument Panel And Systems for
removal procedures.
(2) Disconnect vacuum line from actuator (Fig. 39).
(3) Remove two nuts retaining vacuum actuator to
recirculation door housing.
(4) Disconnect actuator from recirc. door link.
(5) Remove recirculation door actuator from vehi-
cle.
Fig. 37 Instrument Panel Defrost Duct
24 - 26 HEATING AND AIR CONDITIONINGPL
REMOVAL AND INSTALLATION (Continued)

INSTALLATION
For installation, reverse the above procedures.
SUCTION LINE
WARNING: THE REFRIGERANT MUST BE RECOV-
ERED BEFORE SERVICING ANY PART OF THE
REFRIGERANT SYSTEMS.
REMOVAL
(1) Using a R-134a refrigerant recovery machine,
remove the refrigerant from A/C system.
(2) Remove retaining bolt at expansion valve (Fig.
40).
(3) Remove line at drier.
(4) Remove line at compressor.
INSTALLATION
For installation, reverse the above procedures.
TEMPERATURE CONTROL CABLE
The Control Cable can be removed and installed
without having to remove the instrument panel from
the vehicle.
REMOVAL
(1) Remove instrument panel upper cowl panel.
(2) Remove right side upper instrument panel
bezel (Fig. 35).
(3) Remove center vent duct (Fig. 36).
(4) Remove upper defrost duct (Fig. 37).
(5) Remove inner defrost duct (Fig. 38).
(6) Disconnect cable at heater unit.
(7) Disconnect cable at control panel. Remove con-
trol from instrument panel.
(8) Remove cable from vehicle.
INSTALLATION
For installation, reverse the above procedures,
adjust cable and test. See Temperature Control Cable
Adjustment in this section.
UNIT HOUSING
The instrument panel must be removed in order to
remove the Unit Housing. Refer to group 8E Instru-
ment Panel and Gauges for detailed procedure.
WARNING: THE R-134a REFRIGERANT SYSTEM
MUST BE RECOVERED BEFORE SERVICING ANY
PART OF THE REFRIGERANT SYSTEM.
REMOVAL
(1) Remove instrument panel from vehicle. Refer
to group 8E Instrument Panel and Gauges for
detailed procedure.
(2) Drain cooling system and remove heater hoses
at the dash panel. Place plugs in the heater core out-
lets to prevent coolant spillage during unit housing
removal.
Fig. 40 Bolt RemovalFig. 38 Instrument Panel Inner Defrost Duct
Fig. 39 Recirculation Door Actuator
PLHEATING AND AIR CONDITIONING 24 - 27
REMOVAL AND INSTALLATION (Continued)

(3) Using a refrigerant recovery machine, remove
the refrigerant from the A/C system, if equipped.
(4) Remove suction line at expansion valve. Place a
piece of tape over open refrigerant line to prevent
moisture and/or dirt from entering the line.
(5) Remove expansion valve from evaporator. Place
a piece of tape over open evaporator fitting to pre-
vent moisture and/or dirt from entering the evapora-
tor.
(6) Remove rubber drain tube extension from con-
densation drain tube.
(7) Remove three retaining nuts located in the
engine compartment, on the dash panel (Fig. 41).
(8) Remove the right side retaining screw (Fig. 42).
(9) Remove remaining nut located on dash panel
stud.
(10) Disconnect the blue five way connector from
the plenum. Module wiring harness must be removed
with module.
(11) Remove assembly from the vehicle.
INSTALLATION
For installation, reverse the above procedures.
DISASSEMBLY AND ASSEMBLY
AIR DISTRIBUTION MODULE ± RECONDITION
Use this procedure if any or all of the following
items require service:
²Heater core
²Temperature door
²Mode door
²Heat/Defrost door
²Assembly housing
The unit housing must be removed from the vehi-
cle before beginning with this procedure. Refer to
Unit Housing in this section for removal procedure.
DISASSEMBLE
For RHD vehicles, the Unit Housing does not sep-
arate. It is a one piece unit and must be replaced as
a whole.
(1) Remove the clips and screws that hold the Air
Distribution Module to the Evaporator/Blower Mod-
ule. Then separate the two units (Fig. 43).
(2) Remove the panel opening foam seal, demister
opening foam seal, and heater core tube foam seals
from unit.
(3) Remove the retaining clips and screws that
hold the upper and lower housings together (Fig. 44).
(4) Place the unit in the upside down position.
Then separate the two halves of the module (Fig. 45).
(5) Lift the heater core out of the case (Fig. 46).
(6) Press tab in at base of temperature door and
release door from lever (Fig. 47). Then remove the
door.
Fig. 41 Dash Panel Studs
Fig. 42 Retaining Screws
Fig. 43 Air Distribution and Evaporator/Blower
Module Separation
24 - 28 HEATING AND AIR CONDITIONINGPL
REMOVAL AND INSTALLATION (Continued)

(7) Press tab in at base of mode door and release
door from lever (Fig. 48).
(8) Remove Heat/Defrost door cam screw (Fig. 49).
(9) Lift the cam and mode door lever off of the
housing (Fig. 50).(10) Remove the Heat/Defrost link pivot screw
(Fig. 51).
(11) Lift the Heat/Defrost link and the door as an
assembly. Then separate the link from the door.
Fig. 44 Retaining Clip Removal
Fig. 45 Case Separation
Fig. 46 Heater Core Removal
Fig. 47 Temperature Door Removal
Fig. 48 Mode Door Removal
Fig. 49 Cam Screw Removal
PLHEATING AND AIR CONDITIONING 24 - 29
DISASSEMBLY AND ASSEMBLY (Continued)

ASSEMBLE
To reassemble, reverse the above procedures.
ADJUSTMENTS
MODE CONTROL CABLE
(1) Attach cable to actuator arm on mode door and
clip black casing against the stop.
(2) Attach other end of cable to instrument panel
control.
(3) Turn the mode knob completely counterclock-
wise.
(4) While holding the knob in the counterclockwise
position, pull on the black casing of the mode cable.
This will take up any free play in the cable and index
the mode door to the mode knob.
(5) Then snap the cable hold down clip into posi-
tion.
TEMPERATURE CONTROL CABLE
(1) Attach cable to actuator arm on temperature
door and clip black casing against the stop.
(2) Attach other end of cable to instrument panel
control.
(3) Turn the temperature knob completely counter-
clockwise.
(4) While holding the knob in the counterclockwise
position, pull on the black casing of the temperature
cable. This will take up any free play in the cable
and index the temperature door to the temperature
knob.
(5) Then snap the cable hold down clip into posi-
tion.
(6) Remount control.
Fig. 50 Cam and Lever Removal
Fig. 51 Pivot Screw Removal
24 - 30 HEATING AND AIR CONDITIONINGPL
DISASSEMBLY AND ASSEMBLY (Continued)

HEX
CODEGENERIC
SCAN
TOOL
CODEDRB SCAN TOOL
DISPLAYDESCRIPTION OF DIAGNOSTIC TROUBLE CODE
66 P0133 Right Bank Upstream O2S
Slow ResponseOxygen sensor response slower than minimum required
switching frequency.
67 P0135 Right Rear (or just)
Upstream O2S Heater
FailureUpstream oxygen sensor heating element circuit
malfunction.
69 P0141 Right Rear (or just)
Downstream O2S Heater
FailureOxygen sensor heating element circuit malfunction.
6A P0300 Multiple Cylinder Mis-fire Misfire detected in multiple cylinders.
6B P0301 Cylinder #1 Mis-fire Misfire detected in cylinder #1.
6C P0302 Cylinder #2 Mis-fire Misfire detected in cylinder #2.
6D P0303 Cylinder #3 Mis-fire Misfire detected in cylinder #3.
6E P0304 Cylinder #4 Mis-fire Misfire detected in cylinder #4.
70 P0420 Right Rear (or just)
Catalyst Efficency FailureCatalyst efficiency below required level.
71 P0441 Incorrect Pruge Flow Insufficient or excessive vapor flow dtected during
evaporation emission system operation.
72 P1899 P/N Switch Stuck in Park
or in GearIncorrect input state detected for the Park/Neutral
switch, auto. trans. only.
73* P0551 Power Steering Switch
FailurePower steering high pressure seen at high speed (2.5L
only).
76 P0172 Right Rear (or just) Fuel
System RichA rich air/fuel mixture has been indicated by an
abnormally lean correction factor.
77 P0171 Right Rear (or just) Fuel
System LeanA lean air/fuel mixture has been indicated by an
abnormally rich correction factor.
7E P0138 Right Rear (or just)
Downstream O2S Shorted
to VoltageOxygen sensor input voltage maintained above the
normal operating range.
80 P0125 Closed Loop Temp Not
ReachedEngine does not reach 20ÉF within 5 minutes with a
vehicle speed signal.
81 P0140 Right Rear (or just)
Downstream O2S Stays at
CenterNeither reich or lean condition detected from the
downstream oxygen sensor.
84 P0121 TPS Voltage Does Not
Agree With MAPTPS signal does not correlate to MAP sensor.
85 P1390 Timing Belt Skipped 1
tooth or MoreRelationship between Cam and Crank signal is not
correct.
8A P1294 Target Idle Not Reached Actual idle speed does not equal target idle speed.
91 P1299 Vacuum Leak Found (IAC
Fully Seated)MAP sensor signal does not correlate to throttle position
sensor signal. Possible vacuum leak.
92 P1496 5 Volt Supply Output Too
Low5 volt output from regulator does not meet minimum
requirement.
94* P0740 Torq Conv Clu, No RPM
Drop At LockupRelationship between engine speed and vehicle speed
indicates no torque converter clutch engagement (auto.
trans. only).
PLEMISSION CONTROL SYSTEMS 25 - 5
DESCRIPTION AND OPERATION (Continued)

Following is a description of each system monitor,
and its DTC.
Refer to the appropriate Powertrain Diagnos-
tics Procedures manual for diagnostic proce-
dures.
HEX 66, and 7AÐOXYGEN SENSOR (O2S)
MONITOR
Effective 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 oper-
ating temperature 300É to 350ÉC (572É to 662ÉF), the
sensor generates a voltage that is inversely propor-
tional to the amount of oxygen in the exhaust. The
information obtained by the sensor is used to calcu-
late the fuel injector pulse width. This maintains 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
²Reduced output voltage
²Dynamic shift
²Shorted or open circuits
Response rate is the time required for the sensor to
switch from lean to rich once it is exposed to a richer
than optimum A/F mixture or vice versa. As the sen-
sor starts malfunctioning, it could take longer to
detect the changes in the oxygen content of the
exhaust gas.
The 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 con-
centrations 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.
HEX 67, 69, 7C, and 7DÐOXYGEN SENSOR
HEATER MONITOR
If 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 is repaired, verify that the
heater circuit is operating correctly.
Effective 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 oper-
ating temperature 300É to 350ÉC (572 Éto 662ÉF), the
sensor generates a voltage that is inversely propor-
tional to the amount of oxygen in the exhaust. Theinformation obtained by the sensor is used to calcu-
late the fuel injector pulse width. This maintains 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 nitrogen oxide (NOx) from
the exhaust.
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 O2S circuit is monitored for a drop in voltage.
The sensor output is used to test the heater by iso-
lating the effect of the heater element on the O2S
output voltage from the other effects.
HEX 2EÐEGR MONITOR
The Powertrain Control Module (PCM) performs
an on-board diagnostic check of the EGR system.
The EGR system consists of two main components:
a vacuum solenoid back pressure transducer and a
vacuum operated valve. The EGR monitor is used to
test whether the EGR system is operating within
specifications. The diagnostic check activates only
during selected engine/driving conditions. When the
conditions are met, the EGR is turned off (solenoid
energized) and the O2S compensation control is mon-
itored. Turning off the EGR shifts the air fuel (A/F)
ratio in the lean direction. The O2S data should indi-
cate an increase in the O2 concentration in the com-
bustion chamber when the exhaust gases are no
longer recirculated. While this test does not directly
measure the operation of the EGR system, it can be
inferred from the shift in the O2S data whether the
EGR system is operating correctly. Because the O2S
is being used, the O2S test must pass its test before
the EGR test.
HEX 6A,6B, 6C, 6D, 6E, AE, and AFÐMISFIRE
MONITOR
Excessive engine misfire results in increased cata-
lyst temperature and causes an increase in HC emis-
sions. Severe misfires could cause catalyst damage.
To prevent catalytic convertor damage, the PCM
monitors engine misfire.
The Powertrain Control Module (PCM) monitors
for misfire during most engine operating conditions
(positive torque) by looking at changes in the crank-
shaft speed. If a misfire occurs the speed of the
crankshaft will vary more than normal.
HEX 76, 77, 78, and 79ÐFUEL SYSTEM
MONITOR
To comply with clean air regulations, vehicles are
equipped with catalytic converters. These converters
PLEMISSION CONTROL SYSTEMS 25 - 7
DESCRIPTION AND OPERATION (Continued)