Engine Cooling System Requirements; Evaporator Temperature Sensor; Expansion Valve - Chrysler 2000 LHS Owner's Manual

LH
DESCRIPTION AND OPERATION (Continued)
fixed displacement of 170 cubic centimeters (10.374
cubic inches), and has both the suction and discharge
ports located on the cylinder head. A label identifying
the use of R-134a refrigerant is located on the com-
pressor.
OPERATION
The compressor is driven by the engine through an
electric clutch, drive pulley and belt arrangement.
The compressor is lubricated by refrigerant oil that is
circulated throughout the refrigerant system with the
refrigerant.
The compressor draws in low-pressure refrigerant
vapor from the evaporator through its suction port. It
then compresses the refrigerant into a high-pressure,
high-temperature refrigerant vapor, which is then
pumped to the condenser through the compressor dis-
charge port.
The compressor cannot be repaired. If faulty or
damaged, the entire compressor assembly must be
replaced. The compressor clutch, pulley and clutch
coil are available for service.

ENGINE COOLING SYSTEM REQUIREMENTS

DESCRIPTION
To maintain the performance level of the heating/
air-conditioning system, the engine cooling system
must be prepared as shown in this manual.
The use of a bug screen is not recommended. Any
obstructions in front of the radiator or condenser can
reduce the performance of the A/C and/or engine cool-
ing system.
WARNING: DO NOT
WHEN HOT AS PERSONAL INJURY OR DAMAGE
TO VEHICLE MAY RESULT.
OPERATION
The engine cooling system is designed to develop
internal pressure of 97 to 123 kPa (14 to 18 psi).
Wait 15 minutes (after the engine is shut off), or
until safe temperature and pressure is attained,
before opening cooling system. Refer to Group 7,
Cooling System. Coolant temperature can be checked
using the scan tool (DRBIII ).
When additional coolant is needed, it should be
added to the coolant pressure bottle. Use only 50/50
mix of Mopar Antifreeze/Coolant, 5 Year/100,000
Mile Formula (orange in color), or the equivalent and
distilled water. This coolant must not be mixed with
other (green in color) coolants. If this occurs, a reduc-
tion in the extended service interval will result. Refer
to LUBRICATION AND MAINTENANCE for service
schedules.
OPEN COOLING SYSTEM
HEATING AND AIR CONDITIONING
CAUTION: Do not add additional inhibitors, anti-
rust products, or soluble oil (sold as "water pump
lubricants"). These products may not be compatible
with the engine coolant.
Refer to Group 7, Cooling System for cooling sys-
tem procedures.

EVAPORATOR TEMPERATURE SENSOR

DESCRIPTION
The evaporator temperature sensor is a tempera-
ture sensing element located at the coldest point on
the face of the evaporator. The evaporator tempera-
ture sensor prevents condensate water on the evapo-
rator coil from freezing which can block airflow. The
probe is a thermistor inside a metal tube which is
wedged between the evaporator fins. The metal tube
is tightly held by the evaporator fins so that the ther-
mistor in the tube will detect the temperature of the
evaporator. The thermistor will change resistance as
the temperature changes.
OPERATION
The Body Control Module (BCM) will send a Pro-
grammable Communications Interface (PCI) bus mes-
sage to the Powertrain Control Module (PCM), which
will check engine, coolant temperature, and refriger-
ant pressure temperature before turning ON the A/C
Compressor Clutch. Turning ON the A/C Compressor
Clutch will allow the system to cool the evaporator.
The BCM will send a message to the PCM when the
evaporator temperature becomes too cold. The PCM
will then turn OFF the A/C Compressor Clutch,
before evaporator freeze up occurs. The DRBIII scan
tool can be used to monitor this operation. The tem-
perature setpoint at which the clutch is turned OFF
varies with the outside ambient temperature. The
temperature at which the clutch is turned ON is pre-
set to 2° F above the OFF setpoint mentioned above.
Refer to Evaporator Temperature Sensor Setpoint
table and (Fig. 2) for the correct setpoint.

EXPANSION VALVE

DESCRIPTION
The "H valve" type thermal expansion valve (TXV)
is located at the point where the refrigerant lines
join the evaporator coil on the engine compartment
side of the dash panel.
The expansion valve is a factory calibrated unit
and cannot be adjusted or repaired. If faulty or dam-
aged, the expansion valve must be replaced.
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