Chrysler 300/300 Touring/300C, Dodge Magnum. Manual — part 2333
SENSOR-AMBIENT AIR TEMPERATURE
DESCRIPTION
The ambient air temperature sensor is a variable
resistor that monitors the air temperature outside of
the vehicle. The ATC system uses the sensor data to
maintain optimum cabin temperature levels. The ambi-
ent air temperature sensor is mounted onto the bottom
of the front bumper beam.
OPERATION
The ambient air temperature sensor is a variable resistor that operates on a 5-volt reference signal sent by the front
control module (FCM). The ambient air temperature sensor is connected to the FMC through a two-wire lead and
connector of the vehicle wire harness. The ambient air temperature sensor changes its internal resistance in
response to changes in the outside air temperature, which either increases or decreases the reference signal volt-
age read by the FCM. The FCM converts and broadcasts the sensor data over the controller area network (CAN)
B bus, where it is read by the ATC A/C-heater control and other vehicle control modules.
The ambient air temperature sensor is diagnosed using the scan tool. Refer to 9 - Engine Electrical Diagnostics for
more information.
The ambient air temperature sensor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
REMOVAL
1. Disconnect and isolate the negative battery cable.
2. Raise and support the vehicle.
3. Remove the front end splash shields (Refer to 23 -
BODY/EXTERIOR/FRONT
END
SPLASH
SHIELDS - REMOVAL).
4. Disconnect the wire harness connector (1) from the
ambient air temperature sensor (2).
5. Remove the push pin (3) that secures the ambient
air temperature sensor to the bottom of the front
bumper beam (4).
6. Remove the ambient air temperature sensor from
the front bumper beam.
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CONTROLS
LX
INSTALLATION
1. Position the ambient air temperature sensor (2)
onto the bottom of the front bumper beam (4).
2. Install the push pin (3) that secures the ambient air
temperature sensor to the front bumper beam.
3. Connect the wire harness connector (1) to the
ambient air temperature sensor.
4. Install the front end splash shields (Refer to 23 -
BODY/EXTERIOR/FRONT
END
SPLASH
SHIELDS - INSTALLATION).
5. Lower the vehicle.
6. Reconnect the negative battery cable.
LX
CONTROLS
24 - 367
SENSOR-EVAPORATOR TEMPERATURE
DESCRIPTION
NOTE: LHD model shown. RHD model similar.
The evaporator temperature sensor (1) measures the
temperature of the conditioned air downstream of the
A/C evaporator (2). The evaporator temperature sen-
sor is an electrical thermistor within a molded plastic
case that is inserted into the HVAC housing (3) near
the coldest point of the A/C evaporator. Two terminals
within the connector receptacle (4) connect the sensor
to the vehicle electrical system through a wire lead
and connector of the HVAC wire harness.
The external location of the evaporator temperature
sensor allows the sensor to be removed or installed
without disturbing the refrigerant in the A/C system.
OPERATION
The evaporator temperature sensor is a thermistor that operates on a 5-volt reference signal sent out by the A/C-
heater control. The sensor connects to the A/C-heater control through a two-wire lead and connector of the HVAC
wire harness. The sensor monitors the temperature of the conditioned air downstream of the A/C evaporator and
changes its internal resistance in response to changes in the air temperature. As the temperature increases, the
sensor’s resistance decreases which increases the reference signal voltage read by the A/C-heater control. As the
temperature decreases, the sensor’s resistance increases which decreases the reference signal voltage read by the
A/C-heater control.
The A/C-heater control also uses the reference signal voltage as an indication that conditions are correct to request
A/C operation, should the operator (manually) or the A/C-heater control (automatically) so desire this function. For
the ATC system, the A/C-heater control broadcasts the A/C request on the controller area network (CAN) B bus,
where it is read and processed by the front control module (FCM), which in turn broadcasts it on the CAN C bus,
where it is read and processed by the powertrain control module (PCM). For the MTC system, the A/C-heater con-
trol sends the request for A/C to the CCN via a dedicated mux circuit. The CCN then broadcasts the A/C request on
the CAN B bus, where it is read and processed by the FCM, which in turn broadcasts it on the CAN C bus, where
it is read and processed by the PCM.
The evaporator temperature sensor is diagnosed using a scan tool (Refer to 24 - HEATING & AIR CONDITIONING
- DIAGNOSIS AND TESTING - HEATING AND A/C SYSTEMS) and to 24 - HVAC Electrical Diagnostics for more
information.
The evaporator temperature sensor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
REMOVAL
WARNING: On vehicles equipped with airbags, disable the airbag system before attempting any steering
wheel, steering column, or instrument panel component diagnosis or service. Disconnect and isolate the
negative battery (ground) cable, then wait two minutes for the airbag system capacitor to discharge before
performing further diagnosis or service. This is the only sure way to disable the airbag system. Failure to
take the proper precautions could result in accidental airbag deployment and possible personal injury or
death.
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CONTROLS
LX
NOTE: LHD model shown. RHD model similar.
1. Disconnect and isolate the negative battery cable.
2. Remove the glove box from the instrument panel
(Refer
to
23
-
BODY/INSTRUMENT
PANEL/
GLOVE BOX - REMOVAL).
3. Disconnect the HVAC wire harness connector (1)
from the evaporator temperature sensor (2) located
on the HVAC housing (3) and remove the sensor.
INSTALLATION
NOTE: LHD model shown. RHD model similar.
1. Install the evaporator temperature sensor (2) into
HVAC housing (3).
2. Connect the HVAC wire harness connector (1) to
the evaporator temperature sensor.
3. Install the glove box into the instrument panel
(Refer
to
23
-
BODY/INSTRUMENT
PANEL/
GLOVE BOX - INSTALLATION).
4. Reconnect the negative battery cable.
LX
CONTROLS
24 - 369
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