Chrysler Pacifica. Manual - part 887

• The common feed terminal (30) receives a bat-

tery current input from the battery through a B(+)
circuit at all times.

• The coil ground terminal (85) receives a ground

input through the front/rear blower motor relay con-
trol circuit only when the IPM electronically pulls
the control circuit to ground.

• The coil battery terminal (86) receives a battery

current input from the battery through a B(+) circuit
at all times.

• The normally open terminal (87) provides a bat-

tery current output to the blower motor resistor
(manual temperature control) or blower motor power
module (automatic temperature control) through a
fuse in the IPM on the fused front blower motor
relay output circuit only when the blower motor relay
coil is energized.

• The normally closed terminal (87A) is not con-

nected to any circuit in this application, but provides
a battery current output only when the blower motor
relay coil is de-energized.

The blower motor relay cannot be repaired and, if

faulty or damaged, it must be replaced. Refer to the
appropriate wiring information for diagnosis and
testing of the ISO-standard relay and for complete
HVAC wiring diagrams.

REMOVAL

(1) Disconnect and isolate the negative battery

cable.

(2) Remove the cover from the integrated power

module (IPM) located in the engine compartment
(Fig. 18).

NOTE: Refer to the fuse and relay map on the IPM
cover for front blower motor relay location.

(3) Remove the front blower motor relay from the

IPM.

INSTALLATION

NOTE: Refer to the fuse and relay map on the cover
of the integrated power module (IPM) for front
blower motor relay location.

(1) Position the front blower motor relay to the

proper receptacle in the IPM.

(2) Align the front blower motor relay terminals

with the terminal cavities in the IPM receptacle and
push down firmly on the relay until the terminals
are fully seated.

(3) Install the cover onto the IPM.
(4) Reconnect the negative battery cable.

Fig. 18 Integrated Power Module (IPM)

1 - BATTERY
2 - INTEGRATED POWER MODULE (IPM)
3 - BATTERY THERMAL GUARD

CONTROLS - FRONT

24 - 25

BLOWER MOTOR RELAY (Continued)

BLOWER MOTOR RESISTOR

DESCRIPTION

A blower motor resistor is used on vehicles

equipped

with

the

manual

temperature

control

(MTC)

heating-A/C

system

(Fig.

19).

Vehicles

equipped with the automatic temperature control
(ATC) heating-A/C system use a blower motor power
module, instead of the blower motor resistor (Refer to
24 - HEATING & AIR CONDITIONING/CONTROLS
- FRONT/BLOWER MOTOR POWER MODULE -
DESCRIPTION).

The blower motor resistor is mounted to the rear of

the HVAC housing, directly behind the glove box. The
blower motor resistor consists of a molded plastic
mounting plate with an integral wire connector
receptacle. Concealed behind the mounting plate are
coiled resistor wires contained within a ceramic heat
sink.

The blower motor resistor is accessed for service by

removing the glove box.

OPERATION

The blower motor resistor is connected to the vehi-

cle electrical system through a dedicated wire lead
and connector of the HVAC wire harness. The blower
motor resistor has multiple resistor wires, each of
which will reduce the current flow through the
blower motor to change the blower motor speed.

The blower motor control in the manual tempera-

ture control (MTC) heating-A/C system directs the
ground path for the blower motor through the correct
resistor wire to obtain the selected speed. With the

blower motor control in the lowest speed position, the
ground path for the blower motor is applied through
all of the resistor wires. Each higher speed selected
with the blower motor control applies the blower
motor ground path through fewer of the resistor
wires, increasing the blower motor speed.

The blower motor resistor cannot be adjusted or

repaired and, if faulty or damaged (such as a cracked
ceramic heat sink), it must be replaced.

DIAGNOSIS AND TESTING

FRONT BLOWER MOTOR RESISTOR

WARNING: On vehicles equipped with airbags, dis-
able the airbag system before attempting any steer-
ing 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 air-
bag system. Failure to take the proper precautions
could result in accidental airbag deployment and
possible personal injury or death.

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 (Refer to 24 - HEATING & AIR
CONDITIONING/CONTROLS-FRONT/BLOWER
MOTOR RESISTOR - REMOVAL).

(3) Using

ohmmeter,

check

for

continuity

between all of the blower motor resistor terminals. 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.

Fig. 19 Blower Motor Resistor - Typical

1 - BLOWER MOTOR RESISTOR
2 - WIRE CONNECTOR RECEPTICAL
3 - RESISTORS AND HEAT SINK

24 - 26

CONTROLS - FRONT

REMOVAL

WARNING: The blower motor resistor may get very
hot during normal operation. If the blower motor
was turned on prior to servicing the blower motor
resistor, wait five minutes to allow the blower motor
resistors to cool before performing diagnosis or
service. Failure to take this precaution can result in
possible personal injury.

CAUTION: Do not operate the blower motor with the
blower motor resistor removed from the circuit.
Failure to take this precaution can result in vehicle
damage.

(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 two wire harness connectors

from the blower motor resistor (Fig. 20).

(4) Remove the two screws that secure the blower

motor resistor to the HVAC housing and remove the
resistor.

INSTALLATION

(1) Position the blower motor resistor into the

HVAC housing.

(2) Install the two screws that secure the blower

motor resistor to the HVAC housing. Tighten the
screws to 2 N·m (17 in. lbs.).

(3) Connect the two wire connectors to the blower

motor resistor.

(4) Install the glove box (Refer to 23 - BODY/IN-

STRUMENT PANEL/GLOVE BOX - INSTALLA-
TION).

(5) Reconnect the negative battery cable.

EVAPORATOR TEMPERATURE
SENSOR

DESCRIPTION

The evaporator temperature sensor is a switch that

is installed on the top of the expansion valve in the
right rear corner of the engine compartment. The
sensor has a small probe that is inserted in a small
well in the body of the expansion valve that is filled
with a special silicone-based thermal grease. A small
molded plastic push-in retainer secures the sensor to
a threaded hole in the top surface of the expansion
valve. Two terminals within a molded plastic connec-
tor receptacle on the sensor connect it to the vehicle
electrical system through a take out and connector of
the HVAC wire harness.

The evaporator temperature sensor cannot be

adjusted or repaired and, if faulty or damaged, it
must be replaced.

OPERATION

The evaporator temperature sensor monitors the

temperature of the evaporator through its connection
to the top of the expansion valve. The sensor will
change its internal resistance in response to the tem-
peratures it monitors. The A/C-heater control module
is connected to the sensor through a sensor ground
circuit and a sensor signal circuit. As the evaporator
temperature increases, the resistance of the sensor
decreases and the voltage monitored by the module
decreases. The module uses this monitored voltage
reading to an indication of the evaporator tempera-
ture. The A/C-heater control module is programmed

Fig. 20 Blower Motor Resistor

1 - BLOWER MOTOR RESISTOR
2 - INSTRUMENT PANEL WIRE HARNESS
3 - SCREW (2)
4 - GLOVE BOX OPENING REINFORCEMENT
5 - BLOWER MOTOR PIGTAIL WIRE HARNESS
6 - HVAC HOUSING

CONTROLS - FRONT

24 - 27

BLOWER MOTOR RESISTOR (Continued)

to respond to this input by sending electronic mes-
sages to the powertrain control module (PCM) over
the programmable communications interface (PCI)
data bus, and the PCM then cycles the air condition-
ing compressor clutch as necessary to optimize air
conditioning system performance and to protect the
system from evaporator freezing. The external loca-
tion of the sensor and the use of a retainer allows the
sensor to be removed or installed from the expansion
valve without disturbing the refrigerant in the sys-
tem. The evaporator temperature sensor is diagnosed
using a DRBIII

t scan tool. Refer to Body Diagnostic

Procedures.

REMOVAL

(1) Disconnect and isolate the battery negative

cable.

(2) Remove the air cleaner housing from the right

side of the engine compartment.

(3) Remove the temperature sensor retainer from

the expansion valve (Fig. 21).

(4) Pull the evaporator temperature sensor away

from the expansion valve far enough to access the
red release ring on the wiring connector. Push the
red ring toward the connector to release the lock and
remove the wire harness connector from the evapora-
tor temperature sensor.

(5) Remove the evaporator temperature sensor

from the engine compartment.

INSTALLATION

NOTE: Any grease removed with the evaporator
temperature sensor must be replaced. Failure to do
so could result in poor A/C performance.

(1) Position the evaporator temperature sensor

into the right rear corner of the engine compartment.

(2) Reconnect the wire harness connector to the

evaporator temperature sensor.

(3) Position the evaporator temperature sensor

onto the top of the expansion valve with the sensor
probe inserted into the well in the expansion valve.

(4) Install the temperature sensor retainer.
(5) Reinstall the air cleaner housing into the right

side of the engine compartment.

(6) Reconnect the battery negative cable.
(7) Run the HVAC Cool Down test to verify system

is operating properly (Refer to 24 - HEATING & AIR
CONDITIONING - DIAGNOSIS AND TESTING).

INFRARED TEMPERATURE
SENSOR

DESCRIPTION

The infrared temperature sensor consists of two

infrared transducers that are concealed behind a
clear lens located within the instrument panel
mounted A/C-heater control (Fig. 22). These sensors
are used only on models equipped with the automatic
temperature control (ATC) heating-A/C system.

Fig. 21 Evaporator Temperature Sensor

1 - EXPANSION VALVE
2 - EVAPORATOR TEMPERATURE SENSOR
3 - RETAINER

Fig. 22 Infrared Temperature Sensor

1 - ATC A/C-HEATER CONTROL
2 - INFRARED TEMPERATURE SENSOR

24 - 28

CONTROLS - FRONT

EVAPORATOR TEMPERATURE SENSOR (Continued)

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