Chrysler RG Voyager. Manual - part 1215

BLOWER MOTOR RELAY

DESCRIPTION

The blower motor relay for the front heating-A/C

system is an International Standards Organization
(ISO)-type relay (Fig. 17). Relays conforming to the
ISO specifications have common physical dimensions,
current capacities, terminal functions and patterns.

The front blower motor relay is located in the inte-

grated power module (IPM) in the engine compart-
ment.

OPERATION

The front blower motor relay is an electromechan-

ical switch that uses a low current input from the
front control module (FCM) to control the high cur-
rent output to the blower motor resistor (manual
temperature control) or the blower motor power mod-
ule (automatic temperature control). The movable,
common feed relay contact is held against the fixed,
normally closed relay contact by spring pressure.
When the electromagnetic relay coil is energized, it
draws the movable common feed relay contact away
from the fixed, normally closed relay contact and,
holds it against the fixed, normally open relay con-
tact. This action allows high current to flow to the
blower motor.

When the relay coil is de-energized, spring pres-

sure returns the movable relay contact back against
the fixed, normally closed contact point. The resistor
or diode is connected in parallel with the relay coil,
and helps to dissipate voltage spikes and electromag-
netic interference that can be generated as the elec-
tromagnetic field of the relay coil collapses.

The blower motor relay terminals are connected to

the vehicle electrical system through a receptacle in
the integrated power module (IPM). The inputs and
outputs of the blower motor relay include:

• 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 FCM 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. 17 Front Blower Motor Relay

CONTROLS - FRONT

24 - 25

BLOWER MOTOR RESISTOR

DESCRIPTION

A blower motor resistor is used on vehicles

equipped with the front 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 front blower motor resistor is mounted to the

rear of the front HVAC housing, directly behind the
glove box. The front 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 front blower motor resistor is accessed for ser-

vice by removing the glove box.

OPERATION

The front blower motor resistor is connected to the

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

The blower motor control in the manual tempera-

ture control system directs the ground path for the

front 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 front 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 front 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.

Fig. 18 Front Blower Motor Relay

1 - INTEGRATED POWER MODULE (IPM)
2 - FRONT BLOWER MOTOR RELAY
2 - FRONT CONTROL MODULE (FCM)

Fig. 19 Blower Motor Resistor - Typical

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

24 - 26

CONTROLS - FRONT

BLOWER MOTOR RELAY (Continued)

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.

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 front blower motor resistor (Fig. 20).

(4) Remove the two screws that secure the front

blower motor resistor to the front HVAC housing and
remove the resistor.

INSTALLATION

(1) Position the front blower motor resistor into

the front HVAC housing.

(2) Install the two screws that secure the front

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

(3) Connect the two wire connectors to the front

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 used for the

manual and automatic temperature control systems
on RS models is installed on the top of the HVAC
housing behind the instrument panel and measures
the air temperature downstream of the evaporator
(Fig. 21). The sensor is an electrical thermistor in a
plastic housing that is inserted into the HVAC hous-
ing. Two terminals within the molded plastic connec-
tor receptacle on the sensor connect it to the vehicle

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)

electrical system through a take out and connector of
the HVAC wire harness.

The evaporator temperature sensor used for the

manual and automatic temperature control systems
on RG models is installed on the top of the expansion
valve in the right rear corner of the engine compart-
ment and measures the temperature of the evapora-
tor coils (Fig. 22). The sensor has a small probe that
is inserted in a small well in the body of the expan-
sion 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 connector 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 conditioned air once it passes
through the A/C evaporator. The evaporator temper-
ature sensor will change its internal resistance in
response to the air temperatures it monitors and is
connected to the A/C-heater control through sensor
ground and signal circuits. As the conditioned air

temperature increases, the resistance of the evapora-
tor temperature sensor decreases and the voltage
monitored by the A/C-heater control decreases. The
external location of the evaporator temperature sen-
sor allows the sensor to be removed or installed with-
out disturbing the refrigerant in the A/C system.

The A/C-heater control uses this monitored voltage

reading as an indication of the evaporator tempera-
ture. The A/C-heater control is programmed to
respond to this input by sending electronic messages
to the powertrain control module (PCM) over the con-
troller area network (CAN) data bus. The PCM then
cycles the A/C compressor clutch as necessary to opti-
mize A/C system performance and to protect the A/C
system from evaporator freezing.

The evaporator temperature sensor cannot be

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

The evaporator temperature sensor is diagnosed

using the DRBIII

t scan tool. Refer to Body Diagnos-

tic Procedures.

REMOVAL

RG MODELS

(1) Disconnect and isolate the negative battery

cable.

(2) Remove the air cleaner housing from the right

side of the engine compartment.

Fig. 21 Evaporator Temperature Sensor - Typical

1 - EVAPORATOR TEMPERATURE SENSOR
2 - HVAC HOUSING
3 - A/C EVAPORATOR

Fig. 22 Evaporator Temperature Sensor - RG Models

1 - EVAPORATOR TEMPERATURE SENSOR
2 - A/C EXPANSION VALVE

24 - 28

CONTROLS - FRONT

EVAPORATOR TEMPERATURE SENSOR (Continued)

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