Chrysler 2004 Concorde Service Manual page 1584

24 - 16 CONTROLS
BLOWER MOTOR RESISTOR BLOCK (Continued)
(4) Remove the blower motor resistor retaining
screws.
(5) Remove the blower motor resistor from the
HVAC housing.
INSTALLATION
(1) Install the blower motor resistor in the HVAC
housing.
(2) Install the two screws that secure the blower
motor resistor to the HVAC housing and tighten to
2.2 N·m (20 in. lbs.).
(3) Plug in the harness connector to the blower
motor resistor.
(4) Install the lower right underpanel silencer/
duct.
(5) Connect the negative battery cable remote ter-
minal to the remote battery post(Refer to 8 - ELEC-
TRICAL/BATTERY
INSTALLATION).
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 set point 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 Set point
table and (Fig. 12) for the correct setpoint.
SYSTEM/CABLES -
Fig. 12 EVAPORATOR TEMPERATURE SENSOR SET
EVAPORATOR TEMPERATURE SENSOR SET POINT
AMBIENT TEMPERATURE
SENSOR READING °F (° C)
185 (85)
100 (37.7)
77 (25)
60 (15.5)
-70 (-56.6)
REMOVAL
(1) Open the hood and disconnect the negative bat-
tery cable remote terminal from the remote battery
post (Refer to 8 - ELECTRICAL/BATTERY SYSTEM/
CABLES - REMOVAL).
(2) Remove the right under panel silencer.
(3) Disconnect the wiring connector for the evapo-
rator probe.
(4) At the center of the HVAC housing, locate the
evaporator probe access plate. Using a flat blade pry
tool, pull back on the locking tab. Twist the access
plate counter clockwise one-quarter turn, and push
the plate inside the HVAC housing (Fig. 13).
(5) Orient the plate in such a way that allows it to
be pulled through the mounting hole, and remove it.
(6) Pull the evaporator probe out of evaporator
core.
INSTALLATION
The new probe must not go into the same
hole (in the evaporator coil) that the old probe
was removed.
(1) The evaporator is manufactured with three
holes for probe insertion. Insert the probe in the
uppermost hole.
(2) Insert the access plate inside the HVAC hous-
ing and orientate it so that the locking tab is one-
POINT
A/C CLUTCH OFF
EVAPORATOR TEMPERATURE
SET POINT ° F (° C)
31 (-0.5)
31 (-0.5)
34 (1.1)
35 (1.6)
36 (2.2)
LH