1999 DODGE NEON air conditioning

During any reassembly procedures all pipe fittings
in water jacket, and waterbox require cleaning and
application of thread sealant for entire length of
threads.
ACCESSORY DRIVE BELTS
If the engine is equipped with power steering or air
conditioning, it will have 2 drive belts. One belt
drives the generator, the other drives the Power
Steering and Air Conditioning. (Fig. 2)
COOLANT RECOVERY SYSTEM (CRS)
This system works in conjunction with the radiator
pressure cap to utilize thermal expansion and con-
traction of the coolant to keep the coolant free of
trapped air. The system provides space for expansionand contraction, and a convenient safe method for
checking and adjusting the coolant level at atmo-
spheric pressure without removing the pressure cap.
It also provides some reserve coolant to compensate
for minor leaks and evaporation or boiling losses. All
vehicles are equipped with this system (Fig. 3).
See Coolant Level Check, Service Procedures.
Deaeration and Pressure Cap sections for operation
and service.
Fig. 1 Cooling System Operation
Fig. 2 Drive Belts
Fig. 3 Coolant Recovery System
7 - 2 COOLINGPL
GENERAL INFORMATION (Continued)

ENGINE THERMOSTAT
The engine thermostat is located on the front of
the engine (radiator side) in the thermostat housing/
engine outlet connector. The thermostat has an air
bleed (vent) located in the flange and a O-ring for
sealing incorporate on it. There is a relief in the ther-
mostat housing/outlet connector for the O-ring.
WATER PUMP
The water pump has a diecast aluminum body and
housing with a stamped steel impeller. The water
pump bolts directly to the block (Fig. 4). Cylinder
block to water pump sealing is provided by a rubber
O-ring. The water pump is driven by the timing belt.
Refer to Group 9, Engine section for component
removal to access the water pump.
NOTE: The water pump on all models can be
replaced without discharging the air conditioning
system.
COOLANT
The cooling system is designed around the coolant.
The coolant must accept heat from engine block
metal and in the cylinder head area near the exhaust
valves. Then coolant carries this heat to the radiator
where the tube/fin assemblies of these components
can give off the heat to the air.
MopartAntifreeze or the equivalent is recom-
mended for optimum cooling performance and corro-
sion protection when mixed to a freeze point of -37É C
(-35É F).
COOLANT REPLACEMENT
Refer to Group 0, Lubrication and Maintenance for
schedule.
COOLING SYSTEM PRESSURE CAP
The cooling system is equipped with a pressure cap
that releases pressure at some point within a range
of 97-124 kPa (14-18 psi) (Fig. 5).
The system will operate at higher than atmo-
spheric pressure, which raises the coolant boiling
point, allowing increased radiator cooling capacity.
AUTOMATIC TRANSMISSION OIL COOLER
Oil coolers are internal oil to coolant type, mounted
in the radiator lower tank (Fig. 6). Rubber oil lines
feed the oil cooler and the automatic transmission.
Use only approved transmission oil cooler hose. Since
these are molded to fit space available, molded hoses
are recommended. Tighten Oil Cooler Hose Clamps
to 2 N´m (18 in. lbs.).
RADIATOR
The radiator is a down-flow type (vertical tubes)
with design features that provide greater strength,
as well as sufficient heat transfer capabilities to keep
the engine satisfactorily cooled (Fig. 6).
ENGINE BLOCK HEATER
The engine block heater is available as an optional
accessory. The heater, operated by ordinary house
current (110 Volt A.C.) through a power cord and con-
nector behind the radiator grille, provides easier
engine starting and faster warm-up when vehicle is
operated in areas having extremely low tempera-
tures.
Fig. 4 Water Pump
Fig. 5 Cooling System Pressure Cap
PLCOOLING 7 - 3
GENERAL INFORMATION (Continued)

WATER PUMP
The water pump body is made of aluminum with a
steel impeller. The water pump is bolted to the frontof the block, and driven by the timing belt. The water
pump is the heart of the cooling system, pumping the
coolant through the engine block, cylinder head,
heater core, and radiator.
NOTE: The water pump on all models can be
replaced without discharging the air conditioning
system.
Fig. 8 Hose Clamp Tool
7 - 6 COOLINGPL
DESCRIPTION AND OPERATION (Continued)

DIAGNOSIS AND TESTING
COOLING SYSTEM DIAGNOSIS
CONDITION POSSIBLE CAUSE CORRECTION
TEMPERATURE GAUGE READS
LOW1. Has a Diagnostic Trouble Code
(DTC) been set indicating a stuck
open engine thermostat?1. Refer to On Board Diagnostic in
Group 25. Replace thermostat if
necessary. If a (DTC) has not been
set, the problem may be with the
temperature gauge.
2. Is the temperature gauge (if
equipped) connected to the
temperature gauge coolant sensor
on the engine?2. Check the connector at the
engine coolant sensor. Refer to
Group 8E. Repair as necessary.
3. Is the temperature gauge (if
equipped) operating OK?3. Check Gauge operation. Refer to
Group 8E. Repair as necessary.
4. Coolant level low during cold
ambient temperature, accompanied
by poor heater performance.4. Check coolant level in the coolant
overflow/reserve tank and the
radiator. Inspect the system for
leaks. Repair as necessary. Refer to
WARNINGS outlined in this section
before removing pressure cap.
TEMPERATURE GAUGE READS
HIGH OR ENGINE COOLANT
WARNING LAMP ILLUMINATES.
COOLANT MAY OR MAY NOT BE
LOST FROM SYSTEM.1. Trailer being towed, a steep hill
being climbed, vehicle being
operated in slow moving traffic, or
engine idling during high ambient
(outside) temperatures with air
conditioning on. High altitudes
Could aggravate these conditions.1. This may be a temporary
condition and repair is not
necessary. Turn off the air
conditioning and drive the vehicle
without any of the previous
conditions. Observe the temperature
gauge the gauge should return to
the normal range. If the gauge does
not return to the normal range,
determine the cause of the
overheating and repair. Refer to
POSSIBLE CAUSES in this section.
2. Is temperature gauge (if
equipped) reading correctly?2. Check gauge. Refer to Group 8E.
Repair as necessary.
3. Is temperature warning lamp (if
equipped) illuminating
unnecessarily?3. Check warning lamp operation.
Refer to Group 8E. Repair as
necessary.
4. Coolant low in overflow/reserve
tank and radiator?4. Check for coolant leaks and
repair as necessary. Refer to
checking cooling system for leaks in
this group.
5. Pressure cap not installed tightly.
If cap is loose, boiling point of
coolant will be lowered. Also refer
to the following step 6.5. Tighten cap.
6. Poor seals at radiator cap. 6. (a) Check condition of cap and
cap seals. Refer to Radiator cap
Inspection. Replace cap if
necessary.
6. (b) Check condition of filler neck.
If neck is bent or damaged, replace
neck.
PLCOOLING 7 - 7

COOLING SYSTEM DIAGNOSIS CONT.
CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE READS
HIGH OR ENGINE COOLANT
WARNING LAMP ILLUMINATES.
COOLANT MAY OR MAY NOT BE
LOST FROM SYSTEM.7. Coolant level low in radiator but
not in coolant overflow/reserve
tank. This means the radiator is not
drawing coolant from the coolant
overflow/reserve tank as the engine
cools.
As the engine cools, a vacuum is
formed inside the cooling system. If
the radiator cap seals are defective,
or the cooling system has a leak, a
vacuum can not be formed.7. (a) Check condition of radiator
cap and cap seals. Replace cap if
necessary.
(b) Check condition of filler neck. If
neck is damaged, replace filler
neck.
(c) Check condition of hoses from
filler neck to coolant tank. It should
be tight at both ends without any
kinks or tears. Replace hose if
necessary.
(d) Check coolant overflow/reserve
tank and tank hoses for blockage.
Repair as necessary.
8. Freeze point of coolant not
correct. Mixture may be to rich.8. Check coolant. Refer to coolant
section in this group. Adjust glycol
to water ratio as required.
9. Coolant not flowing through
system.9. Check for coolant flow at filler
neck with some coolant removed,
engine warm and thermostat open.
Coolant should be observed flowing
through filler neck. If flow is not
observed determine reason for lack
of flow and repair as necessary.
10. Radiator or A/C condenser fins
are dirty or clogged.10. Clean insects or debris.
11. Radiator core is plugged or
corroded.11. Replace or re-core radiator.
12. Fuel or ignition system
problems.12. Refer to Fuel and Ignition
System group for diagnosis. Also
refer to the appropriate Powertrain
Diagnosis Procedures manual for
operation of the DRB scan tool.
13. Dragging brakes. 13. Inspect brake system and repair
as necessary. Refer to Group 5,
Brakes for diagnosis.
14. Bug screen is being used
causing reduced air flow.14. Remove bug screen.
15. Thermostat partially or
completely shut. This is more
prevalent on high mileage vehicles.15. Check thermostat operation and
replace as necessary. Refer to
thermostats in this group.
16. Electric cooling fan not
operating properly.16. Check electric fan operation and
repair as necessary.
17. Cylinder head gasket leaking. 17. Check cylinder head gasket for
leaks. Refer to testing cooling
system for leaks. For repairs, refer
to group 9, Engines.
18. Heater core leaking. 18. Check heater core for leaks.
Refer to Group 24, Heating and Air
Conditioning. Repair as necessary.
7 - 8 COOLINGPL
DIAGNOSIS AND TESTING (Continued)

COOLING SYSTEM DIAGNOSIS CONT.
CONDITION POSSIBLE CAUSES CORRECTION
INADEQUATE AIR CONDITIONER
PERFORMANCE (COOLING
SYSTEM SUSPECTED)1. Radiator and/or air conditioning
condenser is restricted, obstructed
or dirty.1. Remove restriction and/or clean
as necessary.
2. Electric radiator fan not operating
when a/c is on.2. Refer to appropriate Powertrain
Diagnostic Procedures manual for
operation of the DRB scan tool.
repair as necessary.
3. Engine is overheating ( heat may
be transferred from radiator to A/C
condenser. High underhood
temperature due to engine
overheating may also transfer heat
to A/C components).3. Correct overheating condition.
Refer to Group 7, Cooling.
INADEQUATE HEATER
PERFORMANCE.1. Has a diagnostic trouble code
(DTC) been set?1. Refer to On-Board Diagnostic in
Group 25, and replace thermostat if
necessary.
2. Coolant level low. 2. Refer to testing cooling system
for leaks in this section. Repair as
necessary.
3. Obstructions in heater hose
fittings at engine.3. Remove heater hoses at both
ends and check for obstructions.
Repair as necessary.
4. Heater hose kinked. 4. Locate kinked area and repair as
necessary.
5. Water pump is not pumping
coolant to heater core. When the
engine is fully warmed up, both
heater hoses should be hot to the
touch. The accessory drive belt
may be slipping causing poor water
pump operation.5. Refer to water pump in this
group. Repair as necessary. If
slipping belt is detected, refer to
accessory drive belts in this group.
Repair as necessary.
HEAT ODOR 6. Various heat shields are used at
certain drive line components. One
or more of these shields may be
missing.6. Locate missing shields and
replace or repair as necessary.
PLCOOLING 7 - 11
DIAGNOSIS AND TESTING (Continued)

WATER PUMP DIAGNOSIS
A quick flow test to tell whether or not the pump is
working is to see if the heater warms properly. A
defective pump will not be able to circulate heated
coolant through the long heater hose.
Another flow test to help determine pump opera-
tion.
WARNING: DO NOT remove radiator cap if the cool-
ing system is hot or under pressure.
(1) Remove radiator cap.
(2) Remove a small amount of coolant from the
system, start the engine and warm up until thermo-
stat opens. With the thermostat open and coolant
level low you will see if the water pump is pumping
coolant through the system.
COOLING SYSTEM FLOW CHECK
To determine whether coolant is flowing through
the cooling system, use the following procedures:
(1) If engine is cold, idle engine until normal oper-
ating temperature is reached. Then feel the upper
radiator hose. If it is hot, coolant is circulating.
WARNING: DO NOT REMOVE THE COOLING SYS-
TEM PRESSURE CAP WITH THE SYSTEM HOT AND
UNDER PRESSURE BECAUSE SERIOUS BURNS
FROM COOLANT CAN OCCUR.
(2) Remove pressure cap when engine is cold,
remove small amount of coolant Idle engine until
thermostat opens, you should observe coolant flow
while looking down the filler neck. Once flow is
detected install the pressure cap.
RADIATOR FAN CONTROL
Fan control is accomplished two ways. The fan
always runs when the air conditioning compressor
clutch is engaged. In addition to this control, the fan
is turned on by the temperature of the coolant which
is sensed by the coolant temperature sensor which
sends the message to the Powertrain Control Module
(PCM). The (PCM) turns on the fan through the
Solid State Fan Relay. The Solid State Fan Relay is
located on the left front inner frame just behind the
radiator. See Wiring Diagrams Manual for circuity
and diagnostics provided.
Switching through the (PCM) provides fan control
for the following conditions.
²The fan will not run during cranking until the
engine starts no matter what the coolant tempera-
ture is.
²Fan will run when the air conditioning clutch is
engaged and low pressure cutout switch is closed.
²Fan will run at vehicle speeds above about 40
mph only if coolant temperature reaches 110ÉC(230ÉF). It will turn off when the temperature drops
to 104ÉC (220ÉF). At speeds below 40 mph the fan
switches on at 102ÉC (215ÉF) and off at 93ÉC (200ÉF).
Refer to Radiator Fan Control Module Group 14,
Fuel Injection for more information.
ELECTRIC FAN MOTOR TEST
Refer to Powertrain Diagnostic Manual for procedure.
TESTING COOLING SYSTEM FOR LEAKS
The system should be full. With the engine not
running, wipe the filler neck sealing seat clean.
Attach a radiator pressure tester to the filler neck,
as shown in (Fig. 9) and apply 104 kPa (15 psi) pres-
sure. If the pressure drops more than 2 psi in 2 min-
utes, inspect the system for external leaks.
Move all hoses at the radiator and heater while
system is pressurize at 15 psi, since some leaks occur
due to engine rock while driving.
If there are no external leaks after the gauge dial
shows a drop in pressure, detach the tester. Start the
engine, and run the engine to normal operating tem-
perature in order to open the thermostat and allow
the coolant to expand. Reattach the tester. If the nee-
dle on the dial fluctuates it indicates a combustion
leak, usually a head gasket leak.
WARNING: WITH THE PRESSURE TESTER IN
PLACE PRESSURE BUILDS UP QUICKLY. ANY
EXCESSIVE PRESSURE BUILD-UP DUE TO CON-
TINUOUS ENGINE OPERATION MUST BE
RELEASED TO A SAFE PRESSURE POINT. NEVER
PERMIT PRESSURE TO EXCEED 138 kPa (20 psi).
If the needle on the dial does not fluctuate, race
the engine a few times. If an abnormal amount of
coolant or steam is emitted from the tail pipe, it may
indicate a faulty head gasket, cracked engine block,
or cracked cylinder head.
Fig. 9 Pressure Testing Cooling SystemÐTypical
7 - 14 COOLINGPL
DIAGNOSIS AND TESTING (Continued)

RADIATOR
REMOVAL
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK PLUG OR THE RADIATOR DRAINCOCK
WITH THE SYSTEM HOT AND UNDER PRESSURE
BECAUSE SERIOUS BURNS FROM COOLANT CAN
OCCUR.
(1) Disconnect negative battery cable from battery.
(2) Drain cooling system. Refer to Cooling System
Draining in this section.
(3) Remove engine air inlet duct.
(4) Remove upper radiator hose from the radiator.
(5) Disconnect and cap automatic transmission
hoses, if equipped.
(6) Remove radiator to battery strut (Fig. 20) and
ground strap.
(7) For vehicles equipped with dual fans: Remove
the battery and battery tray.(8) Remove fan module assembly by disconnecting
fan motor electrical connector.
(9) Remove fan shroud retaining screws, located on
the top of the shroud (Fig. 21). Lift shroud up and
out of bottom shroud attachment clips separating
shroud from radiator. For dual fan applications the
left fan module may be removed first, then the right
side module last. Fan damage should always be
avoided.
(10) Remove the lower radiator hose.
(11) Remove upper radiator isolator bracket
mounting screws (Fig. 20). Disconnect the engine
block heater wire if equipped.
(12) Remove the air conditioning condenser attach-
ing screws located at the front of the radiator, if
equipped (Fig. 22), then lean condenser forward.
NOTE: It is not necessary to discharge the air con-
ditioning system to remove the radiator.
(13) Radiator can now be lifted free from engine
compartment.Care should be taken not to dam-
age radiator cooling fins or water tubes during
removal.
INSTALLATION
(1) Slide radiator down into position behind radia-
tor support (yoke).
(2) Attach air conditioning condenser to radiator, if
equipped (Fig. 22), with four mounting screws and
tighten to 5.4 N´m (50 in. lbs.). Then seat the assem-
bly lower rubber isolators into the mounting holes
provided in the lower crossmember.
(3) Tighten radiator isolator mounting bracket
screws to 10 N´m (90 in. lbs.). The radiator should
have clearance to move up approximately 5 to 8 mm
(0.25 in.) after assembled.
(4) Install lower radiator hose. Align the hose and
position the clamp so it will not interfere with engine
components.
Fig. 18 Thermostat/Engine Outlet ConnectorÐSOHC
Fig. 19 Thermostat/Engine Outlet ConnectorÐDOHC
Fig. 20 Radiator Mounting
PLCOOLING 7 - 19
REMOVAL AND INSTALLATION (Continued)