2000 DODGE NEON heater

SIDE WINDOW DEMISTERS
The demisters direct air from the unit housing
through the outlets located on the top corners of the
instrument panel. The demisters operate when the
mode selector is anywhere between floor and defrost
settings. Some air may be noticeable from the demis-
ter outlets when the mode selector is in the bilevel to
floor positions.
SYSTEM AIRFLOW
The system pulls outside (ambient) air through the
cowl opening at the base of the windshield. Then it
goes into the plenum chamber above the unit hous-
ing. On air conditioned vehicles, the air passes
through the evaporator. Air flow can be directed
either through or around the heater core. This is
done by adjusting the blend-air door with the TEMP
control on the instrument panel. The air flow can
then be directed from the panel, floor and defrost
outlets in various combinations using the mode selec-
tor. There are 17 different mode selections possible.
Air flow velocity can be adjusted with the blower
speed selector switch on the instrument panel.
On A/C equipped vehicles the ambient air intake
can be controlled by opening and closing the recircu-
lating air door. When placed in RECIRC, air that is
inside vehicle is removed continuously and recircu-
lated through unit housing. Ambient air cannot be
controlled on vehicles without A/C. The system uses
outside air at all times.
The air conditioning compressor can be engaged by
turning the fan switch counterclockwise from the off
position. It can also be engaged by placing the mode
control in the mix to defrost positions. This will
remove heat and humidity from the air before it is
directed through or around the heater core.
SYSTEM OIL LEVEL
It is important to have the correct amount of oil in
the A/C system to ensure proper lubrication of the
compressor. Too little oil will result in damage to the
compressor. Too much oil will reduce the cooling
capacity of the system and consequently result in
higher discharge air temperatures.
Fig. 7 High Pressure Cut Out Switch Location
1 ± DISCHARGE LINE
2 ± A/C COMPRESSOR
3 ± HIGH PRESSURE CUT OUT SWITCH
4 ± SUCTION LINE
Fig. 8 Low Pressure Cut Off Switch
1 ± EXPANSION VALVE
2 ± LOW PRESSURE CUTOFF SWITCH
3 ± LIQUID LINE
4 ± SUCTION LINE
PLHEATING AND AIR CONDITIONING 24 - 7
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)

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)

VACUUM CONTROL SYSTEM
Use an adjustable vacuum test set (Special Tool
C-3707-B) and a suitable vacuum pump to test the
heater-A/C vacuum control system. With a finger
placed over the end of the vacuum test hose probe
(Fig. 15), adjust the bleed valve on the test set gauge
to obtain a vacuum of exactly 27 kPa (8 in. Hg.).
Release and block the end of the probe several times
to verify that the vacuum reading returns to the
exact 27 kPa (8 in. Hg.) setting. Otherwise, a false
reading will be obtained during testing.
Fig. 14 Charge Determination Chart
Fig. 15 Adjust Vacuum Test Bleed Valve - Typical
1 ± VACUUM PUMP TOOL C-4289
2 ± VACUUM TEST SET C-3707
3 ± BLEED VALVE
4 ± PROBE
PLHEATING AND AIR CONDITIONING 24 - 15
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)

obtained, add or subtract shims until desired read-
ing is obtained.
(8) Install compressor shaft bolt. Tighten to 17.56
2 N´m (155620 in. lbs.) torque.
NOTE: Shims may compress after tightening shaft
nut. Check air gap in four or more places to verify if
air gap is still correct. Spin pulley for final check.
CLUTCH BREAK-IN
After new clutch installation, cycle the A/C clutch
20 times (5 seconds on and 5 seconds off). During
this procedure, set the system to the A/C mode,
engine rpm at 1500 - 2000, and high blower speed.
This procedure (burnishing) will seat the opposing
friction surfaces and provide a higher clutch torque
capability.
CONDENSATION DRAIN TUBE
REMOVAL
(1) Raise vehicle.
(2) Locate rubber drain tube on right side of dash
panel (Fig. 30).
(3) Squeeze clamp and remove drain tube.
INSTALLATION
To install, reverse the preceding operation. Check
the drain tube nipple on the heater-A/C housing for
any obstructions.
CONDENSER
The condenser is located in front of the engine
radiator. It has no serviceable parts. If damaged or
leaking, the condenser assembly must be replaced.
WARNING: THE REFRIGERANT MUST BE
REMOVED FROM THE SYSTEM BEFORE REMOV-
ING THE CONDENSER.
REMOVAL
(1) Using a R-134a refrigerant recovery machine,
remove the refrigerant from the A/C system.
(2) Remove battery support strut.
(3) Remove refrigerant lines from condenser (Fig.
31).
(4) Remove upper radiator mounts.
(5) Remove condenser to radiator mounting
screws.
(6) Tilt radiator back and remove condenser.
INSTALLATION
For installation, reverse the above procedures.
²Tighten the condenser refrigerant lines to 5 N´m
(45 in lbs).
Fig. 29 Installing Pulley Assembly
1 ± PULLEY ASSEMBLY
2 ± WOOD BLOCK
Fig. 30 Condensate Water Drain Tube ± Typical
1 ± DASH PANEL (UNDER HOOD RIGHT SIDE)
2 ± CLAMP
3 ± CONDENSATE DRAIN TUBE
4 ± NIPPLE-A/C HEATER HOUSING
PLHEATING AND AIR CONDITIONING 24 - 25
REMOVAL AND INSTALLATION (Continued)