Chrysler Town, Dodge Caravan. Manual - part 503

REMOVAL

The single zone heating and air conditioning sys-

tem is equipped with a single blend door actuator.
The dual zone system has two blend door actuators,
one for the driver side blend air door and one for the
passenger side blend air door. The same service pro-
cedures can be used for each of these actuators.

WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.

(1) Disconnect and isolate the battery negative

cable.

(2) Remove the silencer from beneath the driver

side end of the instrument panel. (Refer to 23 -
BODY/INSTRUMENT

PANEL/INSTRUMENT

PANEL SILENCER - REMOVAL).

(3) Remove the three screws that secure the heater

core shield to the left end of the HVAC distribution
housing (Fig. 4).

(4) Pull the heater core shield rearward far enough

to disengage the two location tabs that position the

front of the shield to the receptacles in the two lower
finger formations of the heater/ air conditioner hous-
ing near the dash panel.

(5) Remove the heater core shield from the distri-

bution housing.

(6) Disconnect the HVAC wire harness connector

for the blend door actuator from the actuator connec-
tor receptacle (Fig. 5).

(7) Remove the two screws that secure the blend

door actuator to the distribution housing.

(8) Remove the blend door actuator from the dis-

tribution housing.

INSTALLATION

(1) Position the blend door actuator onto the heat-

er/air conditioner housing. If necessary, rotate the
actuator slightly to align the splines on the actuator
output shaft with those in the blend air door linkage.

(2) Install and tighten the two screws that secure

the blend door actuator to the distribution housing.
Tighten the screws to 2 N·m (17 in. lbs.).

(3) Reconnect the HVAC wire harness connector

for the blend door actuator to the actuator connector
receptacle.

(4) Position the heater core shield onto the distri-

bution housing. Be certain that the two location tabs
on the front of the shield are engaged in the recepta-
cles in the two lower finger formations of the evapo-
rator housing near the dash panel.

(5) Install and tighten the three screws that secure

the heater core shield to the left end of the heater/air

Fig. 4 Heater Core Shield

1 - HEATER/ AIR CONDITIONER HOUSING
2 - HEATER CORE SHIELD
3 - DISTRIBUTION HOUSING
4 - SCREWS (3)
5 - LOCATION TABS (2)

Fig. 5 Blend Door Actuator

1 - CONNECTOR
2 - MODE DOOR ACTUATOR
3 - SCREW (2)
4 - DRIVER BLEND DOOR ACTUATOR (DUAL-ZONE ONLY)
5 - HEATER CORE
6 - BLEND DOOR ACTUATOR (SINGLE ZONE) OR PASSENGER
BLEND DOOR ACTUATOR (DUAL-ZONE)

24 - 12

CONTROLS - FRONT

BLEND DOOR ACTUATOR (Continued)

conditioner housing. Tighten the screws to 2 N·m (17
in. lbs.).

(6) Reinstall the silencer under the driver side end

of the instrument panel. (Refer to 23 - BODY/IN-
STRUMENT

PANEL/INSTRUMENT

PANEL

SILENCER - INSTALLATION).

(7) Reconnect the battery negative cable.
(8) Perform the heater-A/C control calibration pro-

cedure. (Refer to 24 - HEATING & AIR CONDITION-
ING/CONTROLS - FRONT/A/C-HEATER CONTROL
- STANDARD PROCEDURE - HEATER-A/C CON-
TROL CALIBRATION).

BLOWER MOTOR RELAY

DESCRIPTION

The blower motor relay (Fig. 6) is a International

Standards Organization (ISO) mini-relay. Relays con-
forming to the ISO specifications have common phys-
ical

dimensions,

current

capacities,

terminal

patterns, and terminal functions. The ISO mini-relay
terminal functions are the same as a conventional
ISO relay. However, the ISO mini-relay terminal pat-
tern (or footprint) is different, the current capacity is
lower, and the physical dimensions are smaller than
those of the conventional ISO relay. The blower
motor relay is located in the Intelligent Power Mod-
ule (IPM), which is in the engine compartment near
the battery. See the fuse and relay layout map
molded into the inner surface of the IPM cover for
blower motor relay identification and location.

The black, molded plastic case is the most visible

component of the blower motor relay. Five male
spade-type terminals extend from the bottom of the
base to connect the relay to the vehicle electrical sys-
tem, and the ISO designation for each terminal is
molded into the base adjacent to each terminal.

OPERATION

The blower motor relay is an electromechanical

switch that uses a low current input from the Front
Control Module (FCM) to control the high current
output to the blower motor resistor (manual heater-
A/C control) or blower power module (ATC control).
The movable common feed contact point is held
against the fixed normally closed contact point by
spring pressure. When the relay coil is energized, an
electromagnetic field is produced by the coil wind-
ings. This electromagnetic field draws the movable
relay contact point away from the fixed normally
closed contact point, and holds it against the fixed
normally open contact point. When the relay coil is
de-energized, spring pressure returns the movable
contact point back against the fixed normally closed
contact point. The resistor or diode is connected in
parallel with the relay coil in the relay, and helps to
dissipate voltage spikes and electromagnetic interfer-
ence that can be generated as the electromagnetic
field of the relay coil collapses.

The blower motor relay terminals are connected to

the vehicle electrical system through a receptacle in
the Intelligent 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 heater-A/C control) or blower power module
(automatic heater-A/C control) through a fuse in the
IPM on the fused front blower motor relay output cir-
cuit only when the blower motor relay coil is ener-
gized.

• 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.

Refer to the appropriate wiring information. The

wiring information includes wiring diagrams, proper
wire and connector repair procedures, further details

Fig. 6 Blower Motor Relay

NUMBER

IDENTIFICATION

COMMON FEED

COIL GROUND

COIL BATTERY

NORMALLY OPEN

87A

NORMALLY CLOSED

CONTROLS - FRONT

24 - 13

BLEND DOOR ACTUATOR (Continued)

on wire harness routing and retention, as well as
pin-out and location views for the various wire har-
ness connectors, splices, and grounds.

DIAGNOSIS AND TESTING - BLOWER MOTOR
RELAY

The front blower motor relay (Fig. 7) is located in

the Intelligent Power Module (IPM), which is in the
engine compartment near the battery. See the fuse
and relay layout map molded into the inner surface
of the IPM cover for front blower motor relay identi-
fication and location. Remove the relay from the IPM
to perform the following tests:

(1) A relay in the de-energized position should

have continuity between terminals 87A and 30, and
no continuity between terminals 87 and 30. If OK, go
to Step 2. If not OK, replace the faulty relay.

(2) Resistance between terminals 85 and 86 (elec-

tromagnet) should be 75 ± 5 ohms. If OK, go to Step
3. If not OK, replace the faulty relay.

(3) Connect a battery to terminals 85 and 86.

There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, use a DRBIII

t scan tool to perform

further diagnosis of the relay circuits. Refer to the
appropriate

diagnostic

information.

not

OK,

replace the faulty relay.

REMOVAL

(1) Disconnect and isolate the battery negative

cable.

(2) Unlatch and remove the cover from the Intelli-

gent Power Module (IPM) (Fig. 8).

(3) See the fuse and relay layout map molded into

the inner surface of the IPM cover for front blower
motor relay identification and location.

(4) Remove the front blower motor relay from the

IPM by pulling the relay straight up.

INSTALLATION

(1) See the fuse and relay layout map molded into

the inner surface of the Intelligent Power Module
(IPM) cover for front blower motor relay identifica-
tion and location.

(2) Position the front blower motor relay to the

proper receptacle in the IPM.

(3) Align the front blower motor relay terminals

with the terminal cavities in the IPM relay recepta-
cle.

(4) Push down firmly on the front blower motor

relay until the terminals are fully seated in the ter-
minal cavities in the IPM receptacle.

(5) Install and latch the cover onto the IPM.
(6) Reconnect the battery negative cable.

BLOWER MOTOR RESISTOR

DESCRIPTION

A blower motor resistor is used on this model when

it is equipped with the manual heater-A/C control
(Fig. 9). Models equipped with the optional Auto-
matic Temperature Control (ATC) use a blower power

Fig. 7 Blower Motor Relay - Terminal Legend

NUMBER

IDENTIFICATION

COMMON FEED

COIL GROUND

COIL BATTERY

NORMALLY OPEN

87A

NORMALLY CLOSED

Fig. 8 Intelligent Power Module

1 - BATTERY THERMAL GUARD
2 - INTELLIGENT POWER MODULE
3 - FRONT CONTROL MODULE

24 - 14

CONTROLS - FRONT

BLOWER MOTOR RELAY (Continued)

module, instead of the blower motor resistor. The
blower motor resistor is installed in a mounting hole
in the heater/AC housing, directly behind the glove
box opening of the instrument panel. The resistor
consists of a molded plastic mounting plate with two
integral connector receptacles. Concealed behind the
mounting plate within the heater/AC housing are
four coiled resistor wires contained within a protec-
tive stamped steel cage. The resistor mounting plate
is secured with two screws to the heater/AC housing
and is accessed for service by rolling down the glove
box from the instrument panel.

The blower motor resistor wires will get hot when

in use. Do not touch the resistor wires or the protec-
tive cage if the blower motor has been running. The
blower motor resistor cannot be adjusted or repaired
and, if faulty or damaged, it must be replaced.

OPERATION

The blower motor resistor is connected to the vehi-

cle electrical system through a dedicated take out
and connector of the instrument panel wire harness.
A second connector receptacle receives the pigtail
wire connector from the blower motor. 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 switch in the manual heater-A/C con-
trol directs the ground path for the blower motor
through the correct resistor wire to obtain the

selected speed. With the blower motor switch in the
lowest speed position, the ground path for the motor
is applied through all of the resistor wires. Each
higher speed selected with the blower motor switch
applies the blower motor ground path through fewer
of the resistor wires, increasing the blower motor
speed. When the blower motor switch is in the high-
est speed position, the blower motor resistor wires
are bypassed and the blower motor receives a direct
path to ground through the blower motor switch. The
blower motor resistor may be diagnosed using con-
ventional diagnostic tools and methods.

DIAGNOSIS AND TESTING - BLOWER MOTOR
RESISTOR

Refer to the appropriate wiring information. The

wiring information includes wiring diagrams, proper
wire and connector repair procedures, details of wire
harness routing and retention, connector pin-out
information and location views for the various wire
harness connectors, splices and grounds.

(1) Disconnect and isolate the battery negative

cable.

(2) Disconnect the instrument panel wire harness

connector for the blower motor resistor and the
blower motor pigtail wire connector from the resistor
connector receptacles.

(3) Check for continuity between each of the

blower motor switch input terminals of the blower
motor resistor and the resistor output terminal. In
each case there should be continuity. If OK, repair
the instrument panel wire harness circuits between
the blower motor switch and the blower motor resis-
tor or the blower motor pigtail wires as required. If
not OK, replace the faulty blower motor resistor.

Fig. 9 Blower Motor Resistor

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

CONTROLS - FRONT

24 - 15

BLOWER MOTOR RESISTOR (Continued)

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