Dodge Sprinter. Manual — part 335
(6) Charge the refrigerant system (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE).
AIR OUTLET TEMPERATURE
SENSOR
DESCRIPTION
The air outlet temperature sensor is a two-wire
temperature sensing element that detects the tem-
perature of the air coming out of the heater housing
unit (Fig. 11). The sensor is attached to heater hous-
ing unit directly behind the ATC heater-A/C control
panel. The thermistor will change resistance as the
temperature changes.
OPERATION
The air outlet temperature sensor monitors the
temperature of the air coming out of the heater hous-
ing unit. The sensor will change its internal resis-
tance in response to the temperatures it monitors.
The ATC control module is connected to the sensor
through a sensor ground circuit and a sensor signal
circuit. As the air temperature increases, the resis-
tance of the sensor decreases and the voltage moni-
tored by the module decreases. The operating range
of the air outlet temperature sensor is 0° C (32° F)
and 95° C (203° F). The module uses this monitored
voltage reading to an indication of the outlet air tem-
perature. The ATC control module makes adjust-
ments
to
maintain
the
requested
interior
temperature by cycling both the A/C compressor and
solenoid heater valve on and off.
The air outlet temperature sensor is diagnosed by
performing the ATC Function Test using the DRBIII
t
scan tool. Refer to Body Diagnostic Procedures.
The air outlet temperature sensor cannot be
adjusted or repaired, and if faulty or damaged, it
must be replaced.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the heater-A/C control from the instru-
ment panel (Refer to 24 - HEATING & AIR CONDI-
TIONING/CONTROLS/A/C HEATER CONTROL -
REMOVAL).
(3) Disconnect the wire harness connector from the
air outlet temperature sensor (Fig. 12).
(4) Remove the air outlet temperature sensor from
the heater housing.
INSTALLATION
(1) Install the air outlet temperature sensor onto
the heater housing.
(2) Connect the wire harness connector to the air
outlet temperature sensor.
(3) Install the heater-A/C control into the instru-
ment panel (Refer to 24 - HEATING & AIR CONDI-
TIONING/CONTROLS/A/C HEATER CONTROL -
INSTALLATION).
(4) Reconnect the battery negative cable.
Fig. 11 Air Outlet Temperature Sensor
1 - AIR OUTLET TEMPERATURE SENSOR
2 - NTC THERMISTOR
3 - WIRE CONNECTOR
Fig. 12 Air Outlet Temperature Sensor
1 - HEATER HOUSING
2 - AIR OUTLET TEMPERATURE SENSOR
24 - 16
CONTROLS-FRONT
VA
AMBIENT TEMPERATURE SEN-
SOR
DESCRIPTION
The ambient air temperature sensor is a variable
resistor that monitors the air temperature outside of
the vehicle. The ambient air temperature sensor is
connected to the instrument cluster through a two-
wire harness lead and connector of the vehicle elec-
trical system (Fig. 13). The instrument cluster sends
out a message on the CAN bus to the ATC control
module which uses the sensor data to maintain opti-
mum cabin temperature levels.
The ambient air temperature sensor is mounted to
the front licence plate bracket by three integral
retaining tabs.
OPERATION
The ambient temperature sensor is a variable
resistor that operates on a five-volt reference signal
sent to it by the instrument cluster. The resistance in
the sensor changes as temperature changes. Based
upon the resistance in the sensor, the instrument
cluster sends the ATC control module a specific volt-
age on the temperature sensor signal circuit, which
is programmed to correspond to a specific tempera-
ture.
The ambient temperature sensor is diagnosed
using the DRBIII
t scan tool. Refer to Body Diagnos-
tic Procedures.
The
ambient
temperature
sensor
cannot
be
adjusted or repaired and, if faulty or damaged, it
must be replaced.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the front license plate bracket (Refer
to
23
-
BODY/EXTERIOR/LICENSE
PLATE
BRACKET - REMOVAL).
(3) Disconnect the wire harness connector from the
ambient temperature sensor (Fig. 14).
(4) Disengage
the
sensor
retaining
tabs
and
remove the ambient temperature sensor from the
front license plate bracket.
INSTALLATION
(1) Install the ambient temperature sensor onto
the front license plate bracket. Make sure the retain-
ing tabs are fully engaged.
(2) Connect the wire harness connector to the
ambient temperature sensor.
(3) Install the front license plate bracket (Refer to
23 - BODY/EXTERIOR/LICENSE PLATE BRACKET
- INSTALLATION).
(4) Reconnect the battery negative cable.
BLOWER MOTOR RESISTOR
DESCRIPTION
This temperature control system uses a blower
motor resistor (Fig. 15). The blower motor resistor is
mounted to the top of ventilation housing located in
the engine compartment. The blower motor resistor
consists of a molded plastic mounting plate with an
integral retaining tab and wire connector receptacle.
Concealed behind the mounting plate are coiled resis-
tor wires contained within a ceramic heat sink.
Fig. 13 Ambient Air Temperature Sensor
1 - AMBIENT TEMPERATURE SENSOR
2 - WIRE HARNESS CONNECTOR
3 - RETAINING TABS (3)
Fig. 14 Ambient Temperature Sensor
1 - AMBIENT TEMPERATURE SENSOR
2 - FRONT LICENSE PLATE BRACKET
VA
CONTROLS-FRONT
24 - 17
The blower motor resistor is accessed for service
without removing any other components.
OPERATION
The blower motor resistor block has multiple resis-
tor wires. Each resistor wire changes the resistance
in the blower motor current path to change the
blower motor speed. The blower motor switch directs
the current through the correct resistor wire to
obtain the selected speed.
With the blower motor switch in the lowest speed
position, voltage for the motor is applied through all
of the resistor wires. Each higher speed selected with
the blower motor switch applies the blower motor
current path through fewer of the resistor wires,
increasing the blower motor speed. When the blower
motor switch is in the highest speed position, the
blower motor resistor is bypassed and the blower
motor circuit receives a direct path to battery volt-
age.
The blower motor resistor block cannot be repaired
and, if faulty or damaged, it must be replaced.
DIAGNOSIS AND TESTING
BLOWER MOTOR RESISTOR
NOTE: For circuit descriptions and diagrams, refer
to the appropriate wiring information. The wiring
information includes wiring diagrams, proper wire
and connector repair procedures, further details on
wire harness routing and retention, as well as pin-
out and location views for the various wire harness
connectors, splices and grounds.
(1) Disconnect and isolate the negative battery
cable.
(2) Disconnect the wire harness connector from the
blower motor resistor.
(3) Check for continuity between each of the
blower motor switch input terminals of the resistor
and the resistor output terminal. In each case there
should be continuity. If OK, repair the wire harness
circuits between the blower motor switch and the
blower motor resistor or blower motor as required. If
not OK, replace the faulty blower motor resistor.
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Depress the locking tab and remove the blower
motor resistor from the ventilation housing by sliding
the resistor inboard (Fig. 16).
(3) Depress the two locking tabs and disconnect
the wire harness connector from the blower motor
resistor.
(4) Remove the blower motor resistor from the
engine compartment.
INSTALLATION
(1) Connect the wire harness connector to the
blower motor resistor and engage the two locking
tabs.
(2) Install the blower motor resistor into the ven-
tilation housing and engage the locking tab. The
housing is indexed to allow mounting in only one
position.
(3) Reconnect the negative battery cable.
Fig. 15 Front Blower Motor Resistor
1 - MOUNTING PLATE
2 - WIRE CONNECTOR RECEPTACLE
3 - CERAMIC HEAT SINK
Fig. 16 Blower Motor Resistor Block
1 - BLOWER MOTOR RESISTOR
2 - ELECTRICAL CONNECTOR
3 - VENTILATION HOUSING
24 - 18
CONTROLS-FRONT
VA
BLOWER MOTOR SWITCH
DESCRIPTION
The blower motor is controlled by a thumbwheel-
type blower motor control, mounted in the A/C-heater
control (Fig. 17). The switch allows the selection of
four blower motor speeds with the ignition switch in
the On position.
NOTE: The blower motor will operate only at the
lowest speed when the Residual Engine Heat Utili-
zation (REST) function is selected, regardless of the
blower speed setting on the A/C-heater control.
OPERATION
When the ignition is turned to On, the integral
blower motor switch within the ATC A/C-heater con-
trol supplies power to the blower motor switch. The
switch directs power to the individual blower driver
circuits through the blower motor resistor block to
the blower motor and then to ground.
The blower motor switch cannot be adjusted or
repaired, and if faulty or damaged, the A/C-heater
control must be replaced (Refer to 24 - HEATING &
AIR
CONDITIONING/CONTROLS/A/C
HEATER
CONTROL - REMOVAL).
DIAGNOSIS AND TESTING
BLOWER MOTOR SWITCH
The blower motor switch can be diagnosed by using
the DRBIII
t scan tool. Refer to Body Diagnostic Pro-
cedures. For circuit descriptions and diagrams, refer
to the appropriate wiring information.
EVAPORATOR TEMPERATURE
SENSOR
DESCRIPTION
The evaporator temperature sensor measures the
temperature of the conditioned air downstream of the
A/C evaporator (Fig. 18). The evaporator temperature
sensor is an electrical thermistor within a molded
plastic case that is inserted into the HVAC housing
near the coldest point of the A/C evaporator. Two ter-
minals within the connector receptacle 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 tempera-
ture sensor allows the sensor to be removed or
installed without disturbing the refrigerant in the
A/C system.
OPERATION
The evaporator temperature sensor monitors the
temperature of the A/C evaporator. The sensor will
change its internal resistance in response to the tem-
peratures it monitors. The A/C-heater control is con-
nected to the sensor through a sensor ground circuit
and a sensor signal circuit. As the evaporator tem-
perature increases, the resistance of the sensor
decreases and the voltage monitored by the A/C-
heater control decreases. The A/C-heater control uses
this monitored voltage reading to an indication of the
evaporator temperature. The A/C-heater control is
programmed to respond to this input by cycling the
A/C compressor clutch off if the evaporator tempera-
ture sensor reads between 1° C (33° F) and 3.5° C
(38° F) to protect the A/C evaporator from freezing.
Fig. 17 A/C-Heater Control
Fig. 18 Sensor-Evaporator Temperature
1 - EVAPORATOR TEMPERATUE SENSOR
2 - A/C EVAPORATOR
3 - HVAC HOUSING
4 - WIRE CONNECTOR
VA
CONTROLS-FRONT
24 - 19
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