2002 CHRYSLER CARAVAN heating

The compressor clutch plate and pulley unit, or the
clutch coil are available for separate service replace-
ment. The clutch coil zener diode is integral to the
clutch coil pigtail wire and connector and, if faulty or
damaged, the clutch electromagnetic coil unit must
be replaced.
OPERATION
The compressor clutch components provide the
means to engage and disengage the compressor from
the engine serpentine accessory drive belt. When the
clutch coil is energized, it magnetically draws the
clutch plate into contact with the clutch pulley and
drives the compressor shaft. When the coil is not
energized, the pulley freewheels on the clutch hub
bearing, which is part of the pulley.
A zener diode is connected in parallel with the
clutch electromagnetic coil. This diode controls the
dissipation of voltage induced into the coil windings
by the collapsing of the electromagnetic fields that
occurs when the compressor clutch is disengaged.
The zener diode dissipates this induced voltage by
regulating a current path to ground. This arrange-
ment serves to protect other circuits and components
from potentially damaging voltage spikes in the vehi-
cle electrical system that might occur if the voltage
induced in the clutch coil windings could not be dis-
sipated.
The compressor clutch engagement is controlled by
several components: the heater-A/C controls in the
passenger compartment, the A/C pressure transducer
on the liquid line, the evaporator temperature sensor
on the expansion valve, the Powertrain Control Mod-ule (PCM) in the engine compartment, and the com-
pressor clutch relay in the Intelligent Power Module
(IPM). The PCM may delay compressor clutch
engagement for up to thirty seconds. (Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/POWERTRAIN CONTROL MODULE -
DESCRIPTION - PCM OPERATION).
STANDARD PROCEDURE
STANDARD PROCEDURE - COMPRESSOR
CLUTCH AIR GAP
If a new clutch plate and/or clutch pulley are being
used, the air gap between the clutch plate and clutch
pulley must be checked using the following proce-
dure:
(1) Using feeler gauges, measure the air gap
between the clutch plate and the clutch pulley fric-
tion surfaces.
(2) If the air gap is not between 0.5 and 0.9 mm
(0.020 and 0.035 in.), add or subtract shims until the
desired air gap is obtained.
NOTE: The shims may compress after tightening
the compressor shaft bolt. Check the air gap in four
or more places on the clutch plate to verify that the
air gap is still correct. Spin the clutch pulley before
making the final air gap check.
STANDARD PROCEDURE - COMPRESSOR
CLUTCH BREAK-IN
After a new compressor clutch has been installed,
check that the compressor clutch coil is performing to
specifications. (Refer to 24 - HEATING & AIR CON-
DITIONING/CONTROLS - FRONT/COMPRESSOR
CLUTCH COIL - DIAGNOSIS AND TESTING). If
the clutch coil is performing to specifications, per-
form the compressor clutch break-in procedure. This
procedure (burnishing) will seat the opposing friction
surfaces and provide a higher compressor clutch
torque capability.
(1) Set the heater-A/C controls to the A/C mode,
with the blower switch in the highest speed position.
(2) Start the engine and hold the engine speed at
1500 to 2000 rpm.
(3) Cycle the compressor clutch On and Off about
twenty times (five seconds On, then five seconds Off).
REMOVAL
The refrigerant system can remain fully charged
during compressor clutch, pulley, or coil replacement.
Although the compressor assembly must be removed
from its mounting, the compressor clutch can be ser-
vice with the compressor in the vehicle.
Fig. 11 Compressor Clutch - Typical
1 - CLUTCH PLATE
2 - SHAFT KEY (SOME MODELS)
3 - PULLEY AND BEARING
4 - CLUTCH COIL
5 - CLUTCH SHIMS
6 - SNAP RING
7 - SNAP RING
RSCONTROLS - FRONT24-17
COMPRESSOR CLUTCH (Continued)
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NOTE: A new snap ring must be used to secure the
clutch pulley to the compressor. The bevel side of
the snap ring must face outward.
(5) Using snap ring pliers (Special Tool C-4574 or
equivalent), install the external snap ring (bevel side
facing outward) that secures the clutch pulley to the
front cover of the compressor. Be certain that the
snap ring is fully and properly seated in the groove.
(6) If the original clutch plate and clutch pulley
are to be reused, reinstall the original shim(s) on the
compressor shaft against the shoulder. If a new
clutch plate and/or clutch pulley are being used,
install a trial stack of shims 1.0 mm (0.040 in.) thick
on the compressor shaft against the shoulder.
(7) Install the clutch plate onto the compressor
shaft.
(8) Install and tighten the compressor shaft nut. If
necessary, a band-type oil filter wrench or a strap
wrench can be placed around the clutch plate to aid
in bolt tightening. Tighten the bolt to 17.5 N´m (155
in. lbs.).
(9) If a new clutch plate and/or clutch pulley are
being installed, the air gap between the clutch plate
and clutch pulley must be checked. (Refer to 24 -
HEATING & AIR CONDITIONING/CONTROLS -
FRONT/COMPRESSOR CLUTCH - STANDARD
PROCEDURE - COMPRESSOR CLUTCH AIR GAP).
(10) On models with the 2.4L engine only, loosely
install the four screws that secure the compressor tothe mounting bracket on the engine. Tighten the
screws to 28 N´m (21 ft. lbs.).
(11) On models with the 3.3L and 3.8L engines
only, loosely install the three screws and one nut that
secure the compressor to the engine. Tighten each of
the fasteners using the following sequence to 54 N´m
(40 ft. lbs.).
²The upper screw at the rear of the compressor.
²The lower screw at the rear of the compressor.
²The lower screw at the front of the compressor.
²The upper nut at the front of the compressor.
(12) On models with the 3.3L and 3.8L engines
only, engage the retainer on the engine wire harness
compressor clutch coil take out with the bracket on
the top of the compressor.
(13) Reconnect the engine wire harness connector
for the compressor clutch coil to the coil pigtail wire
connector on the top of the compressor.
(14) Reinstall the serpentine accessory drive belt
onto the front of the engine. (Refer to 7 - COOLING/
ACCESSORY DRIVE/DRIVE BELTS - 2.4L -
INSTALLATION) or (Refer to 7 - COOLING/ACCES-
SORY DRIVE/DRIVE BELTS - 3.3L/3.8L - INSTAL-
LATION).
(15) Lower the vehicle.
(16) Reconnect the battery negative cable.
(17) If a new clutch plate and/or clutch pulley are
being installed, the new clutch components must be
burnished. (Refer to 24 - HEATING & AIR CONDI-
TIONING/CONTROLS - FRONT/COMPRESSOR
CLUTCH - STANDARD PROCEDURE - COMPRES-
SOR CLUTCH BREAK-IN).
COMPRESSOR CLUTCH COIL
DIAGNOSIS AND TESTING - COMPRESSOR
CLUTCH COIL
The air conditioning compressor clutch coil electri-
cal circuit is controlled by the Powertrain Control
Module (PCM) through the compressor clutch relay,
which is located in the Intelligent Power Module
(IPM) in the engine compartment near the battery.
Begin testing of a suspected compressor clutch coil
problem by performing the preliminary checks.
PRELIMINARY CHECKS
(1) If the compressor clutch will not engage, verify
the refrigerant charge level. (Refer to 24 - HEATING
& AIR CONDITIONING/PLUMBING - FRONT/RE-
FRIGERANT - DIAGNOSIS AND TESTING -
REFRIGERANT CHARGE LEVEL). If the refriger-
ant charge level is OK, go to Step 2. If the refriger-
ant charge level is not OK, adjust the refrigerant
charge as required.
Fig. 16 Install Clutch Pulley
1 - PULLEY ASSEMBLY
2 - WOOD BLOCK
24 - 20 CONTROLS - FRONTRS
COMPRESSOR CLUTCH (Continued)
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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 heater-A/C 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 heater-A/C control module is programmed
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 screw 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 DRBIIItscan tool. Refer to the appropriate
diagnostic information.
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 windshield wiper assembly from
the vehicle(Refer to 8 - ELECTRICAL/WIPERS/
WASHERS/WIPER MODULE - REMOVAL).
(4) Remove the temperature sensor attaching
screw from the expansion valve.
(5) 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 lock and
remove the HVAC wire harness connector from the
temperature sensor.
(6) Remove the evaporator temperature sensor
from the engine compartment. Please note that any
grease removed with the old temperature sensor
must be replaced, failure to do so could result in poor
a/c performance.
INSTALLATION
(1) Position the evaporator temperature sensor
into the right rear corner of the engine compartment.
Please make sure any grease removed with the old
sensor has been replaced before the new sensor is
installed, failure to do so could lead to poor a/c per-
formance.
(2) Reconnect the HVAC wire harness connector
for the evaporator temperature sensor to the sensor
connector receptacle.
(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 retaining screw
and tighten.
(5) Install the window wiper assembly to the vehi-
cle(Refer to 8 - ELECTRICAL/WIPERS/WASHERS/
WIPER MODULE - INSTALLATION).
(6) Reinstall the air cleaner housing into the right
side of the engine compartment.
(7) Reconnect the battery negative cable.
(8) Run the HVAC Cool Down test to verify system
is operating properly(Refer to 24 - HEATING & AIR
CONDITIONING - DIAGNOSIS AND TESTING).
Fig. 18 Evaporator Temperature Sensor
1 - RIGHT FRONT STRUT TOWER
2 - EVAPORATOR TEMPERATURE SENSOR
3 - EXPANSION VALVE
4 - DASH PANEL
5 - RETAINER
RSCONTROLS - FRONT24-23
EVAPORATOR TEMPERATURE SENSOR (Continued)
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INFRARED TEMPERATURE
SENSOR
DESCRIPTION
The infrared temperature sensor consists of two
infrared transducers that are concealed behind a
clear lens located near the bottom of the center panel
outlet near the top of the instrument panel center
bezel (Fig. 19). These sensors are used only on mod-
els equipped with the optional Automatic Tempera-
ture Control (ATC) heating and air conditioning
system. A molded plastic connector receptacle on the
bottom of the panel outlet unit is concealed behind
the center bezel. A short, dedicated jumper wire har-
ness routed behind the center bezel connects the sen-
sors directly to the ATC heater-A/C control module
near the bottom of the center bezel. The infrared
temperature sensor is integral to the center bezel
panel outlet unit. The infrared sensors cannot be
adjusted or repaired and, if faulty or damaged, the
center bezel panel outlet unit must be replaced.
OPERATION
The dual infrared temperature sensors provide
independent measurement inputs to the Automatic
Temperature Control (ATC) heater-A/C control mod-
ule that indicates the surface temperature of the
driver seat and front seat passenger seat occupants.
By using a surface temperature measurement, rather
than an air temperature measurement, the ATC sys-
tem is able to adjust itself to the comfort level as per-
ceived by the occupant. This allows the system to
detect and compensate for other ambient conditions
affecting comfort levels, such as solar heat gain orevaporative heat loss. The ATC system logic responds
to the infrared sensor inputs by calculating and
adjusting the air flow temperature and air flow rate
needed to properly obtain and maintain the individ-
ually selected comfort level temperatures of both the
driver and passenger seat occupants. The ATC heat-
er-A/C control module continually monitors the infra-
red sensor circuits, and will store a Diagnostic
Trouble Code (DTC) for any problem it detects. This
DTC information can be retrieved and the infrared
temperature sensor diagnosed using a DRBIIItscan
tool. Refer to the appropriate diagnostic information.
MODE DOOR ACTUATOR
DESCRIPTION
The mode door actuator is a reversible, 12-volt
Direct Current (DC), servo motor (Fig. 20). The sin-
gle mode door actuator is located on the driver side
end of the heater-A/C housing unit, close to the top of
the distribution housing. The mode door actuator is
mechanically connected to the mode door. The mode
door actuator is interchangeable with the actuators
for the blend air door(s) and the recirculation air
door. Each actuator is contained within an identical
black molded plastic housing with an integral wire
connector receptacle. Two integral mounting tabs
allow the actuator to be secured with two screws to
the heater-A/C unit housing. Each actuator also has
an identical output shaft with splines that connects
Fig. 19 Infrared Temperature Sensor
1 - INSTRUMENT PANEL CENTER BEZEL
2 - CENTER BEZEL OUTLETS
3 - INFRARED TEMPERATURE SENSOR
Fig. 20 Mode 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 - 24 CONTROLS - FRONTRS
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(2) Install and tighten the two screws that secure
the mode 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 mode door actuator to the actuator connector
receptacle.
(4) Reinstall the silencer under the driver side end
of the instrument panel. (Refer to 23 - BODY/IN-
STRUMENT PANEL/INSTRUMENT PANEL
SILENCER - INSTALLATION).
(5) Reconnect the battery negative cable.
(6) 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).
POWER MODULE
DESCRIPTION
A blower power module is used on this model when
it is equipped with the optional Automatic Tempera-
ture Control (ATC) (Fig. 22). Models equipped with
the standard manual heater-A/C control use a blower
motor resistor, instead of the blower power module.
The blower power module is installed in a mounting
hole in the evaporator housing, directly behind the
glove box opening of the instrument panel. The mod-
ule consists of a molded plastic mounting plate with
two integral connector receptacles. Concealed behind
the mounting plate within the evaporator housing is
the power module electronic circuitry and a large
finned, heat sink. The module mounting plate is
secured with two screws to the evaporator housingand is accessed for service by rolling down the glove
box from the instrument panel.
The power module heat sink will get hot when in
use. Do not touch the heat sink if the blower motor
has been running. The blower power module cannot
be adjusted or repaired and, if faulty or damaged, it
must be replaced.
OPERATION
The blower power module 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
power module allows the microprocessor-based Auto-
matic Temperature Control (ATC) heater-A/C control
module to calculate and provide infinitely variable
blower motor speeds based upon either manual
blower switch input or the ATC programming using a
Pulse Width Modulated (PWM) circuit strategy. The
PWM voltage is applied to a comparator circuit
which compares the PWM signal voltage to the
blower motor feedback voltage. The resulting output
drives the power module circuitry, which adjusts the
voltage output received from the blower motor relay
to change or maintain the desired blower speed. The
blower power module is diagnosed using a DRBIIIt
scan tool. Refer to the appropriate diagnostic infor-
mation.
REMOVAL
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) Open the glove box.
(3) Flex both sides of the glove box bin inward
near the top far enough for the rubber glove box stop
bumpers to clear the sides of the glove box opening,
then roll the glove box downward.
(4) Reach through the glove box opening to access
and disconnect the instrument panel wire harness
Fig. 22 Power Module
1 - POWER MODULE
2 - LOWER GLOVE BOX OPENING REINFORCEMENT
3 - EVAPORATOR HOUSING
24 - 26 CONTROLS - FRONTRS
MODE DOOR ACTUATOR (Continued)
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allows the module to monitor the operation and rela-
tive position of the recirculation door actuator and
the recirculation air door. The heater-A/C control
module learns the recirculation air door stop posi-
tions during the calibration procedure and will store
a Diagnostic Trouble Code (DTC) for any problems it
detects in the recirculation door actuator circuits.
The recirculation door actuator can be diagnosed
using a DRBIIItscan tool. Refer to the appropriate
diagnostic information.
REMOVAL
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) Pull the carpet on the passenger side front
floor away from the dash panel far enough to access
the recirculation door actuator.
(3) Disconnect the HVAC wire harness connector
for the recirculation door actuator from the actuator
connector receptacle (Fig. 24).
(4) Remove the two screws that secure the recircu-
lation door actuator to the lower intake air housing.
(5) Remove the recirculation door actuator from
the lower intake air housing.
INSTALLATION
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) Position the recirculation door actuator onto
the lower intake air housing. If necessary, rotate the
actuator slightly to align the splines on the actuator
output shaft with those in the recirculation air door.
(2) Install and tighten the two screws that secure
the recirculation door actuator to the lower intake air
housing. Tighten the screws to 2 N´m (17 in. lbs.).
(3) Reconnect the HVAC wire harness connector
for the recirculation door actuator to the actuator
connector receptacle.
(4) Reposition the carpet on the passenger side
front floor back up to the dash panel.
(5) Reconnect the battery negative cable.
(6) 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).
Fig. 24 Recirculation Door Actuator
1 - LOWER INTAKE AIR HOUSING
2 - RECIRCULATION DOOR ACTUATOR
3 - HVAC WIRE HARNESS
4 - SCREW (2)
5 - LOWER EVAPORATOR HOUSING
24 - 28 CONTROLS - FRONTRS
RECIRCULATION DOOR ACTUATOR (Continued)
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quarter inner panel. Tighten the screw to 11 N´m (97
in. lbs.).
(7) Install and tighten the screw that secures the
back of the rear heater-A/C unit housing to the right
D-pillar. Tighten the screw to 11 N´m (97 in. lbs.).
(8) Install and tighten the two screws that secure
the top of the quarter trim panel attaching bracket to
the quarter inner panel. Tighten the screws to 1.7
N´m (15 in. lbs.).
(9) Reinstall the right quarter trim panel and
right D-pillar trim panel onto the quarter inner
panel. (Refer to 23 - BODY/INTERIOR/QUARTER
TRIM PANEL - INSTALLATION).
(10) Reconnect the battery negative cable.
(11) Perform the heater-A/C control calibration
procedure. (Refer to 24 - HEATING & AIR CONDI-
TIONING/CONTROLS - FRONT/A/C-HEATER CON-
TROL - STANDARD PROCEDURE - HEATER-A/C
CONTROL CALIBRATION).
BLOWER MOTOR RELAY
DESCRIPTION
TERMINAL LEGEND
NUMBER IDENTIFICATION
30 COMMON FEED
85 COIL GROUND
86 COIL BATTERY
87 NORMALLY OPEN
87A NORMALLY CLOSED
The blower motor relay (Fig. 5) is a International
Standards Organization (ISO) mini-relay. Relays con-
forming to the ISO specifications have common phys-
ical dimensions, current capacities, terminalpatterns, 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
compressor clutch 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. The
ISO terminal designations are as follows:
²30 (Common Feed)- This terminal is con-
nected to the movable contact point of the relay.
²85 (Coil Ground)- This terminal is connected
to the ground feed side of the relay control coil.
²86 (Coil Battery)- This terminal is connected
to the battery feed side of the relay control coil.
²87 (Normally Open)- This terminal is con-
nected to the normally open fixed contact point of the
relay.
²87A (Normally Closed)- This terminal is con-
nected to the normally closed fixed contact point of
the relay.
The factory-installed blower motor relay cannot be
adjusted or repaired. If the relay is damaged or
faulty, it must be replaced.
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 (automatic heat-
er-A/C control). The movable common feed contact
point is held against the fixed normally closed con-
tact point by spring pressure. When the relay coil is
energized, an electromagnetic field is produced by the
coil windings. This electromagnetic field draws the
movable relay contact point away from the fixed nor-
mally closed contact point, and holds it against the
fixed normally open contact point. When the relay
coil is de-energized, spring pressure returns the mov-
able contact point back against the fixed normally
closed contact point. The resistor or diode is con-
nected in parallel with the relay coil in the relay, and
helps to dissipate voltage spikes and electromagnetic
interference that can be generated as the electromag-
netic field of the relay coil collapses.
Fig. 5 Blower Motor Relay
24 - 32 CONTROLS - REARRS
BLEND DOOR ACTUATOR (Continued)
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(10) Remove the mode door actuator from between
the rear heater-A/C unit housing and the quarter
inner panel.
INSTALLATION
(1) Position the mode door actuator between the
rear heater-A/C unit housing and the quarter inner
panel.
(2) Reconnect the rear HVAC wire harness connec-
tor for the mode door actuator to the actuator connec-
tor receptacle.
(3) Position the mode door actuator onto the rear
heater-A/C unit housing. If necessary, rotate the
actuator slightly to align the splines on the actuator
output shaft with those in the mode door linkage.
(4) Install and tighten the two screws that secure
the mode door actuator to the rear heater-A/C unit
housing. Tighten the screws to 2 N´m (18 in. lbs.).
(5) Push the top of the rear heater-A/C unit hous-
ing back into position against the right quarter inner
panel.
(6) Install and tighten the screw that secures the
front of the rear heater-A/C unit housing to the right
quarter inner panel. Tighten the screw to 11 N´m (97
in. lbs.).
(7) Install and tighten the screw that secures the
back of the rear heater-A/C unit housing to the right
D-pillar. Tighten the screw to 11 N´m (97 in. lbs.).
(8) Install and tighten the two screws that secure
the top of the quarter trim panel attaching bracket to
the quarter inner panel. Tighten the screws to 1.7
N´m (15 in. lbs.).
(9) Reinstall the right quarter trim panel and
right D-pillar trim panel onto the quarter inner
panel. (Refer to 23 - BODY/INTERIOR/QUARTER
TRIM PANEL - INSTALLATION).
(10) Reconnect the battery negative cable.
(11) Perform the heater-A/C control calibration
procedure. (Refer to 24 - HEATING & AIR CONDI-
TIONING/CONTROLS - FRONT/A/C-HEATER CON-
TROL - STANDARD PROCEDURE - HEATER-A/C
CONTROL CALIBRATION).
POWER MODULE
DESCRIPTION
A blower power module is used on this model when
it is equipped with the optional Automatic Tempera-
ture Control (ATC) (Fig. 11). Models equipped with
the standard manual heater-A/C control use a blower
motor resistor, instead of the blower power module.
The blower power module is installed in a mounting
hole in the back of the rear heater-A/C unit housing,
directly above the expansion valve. The module con-
sists of a molded plastic mounting plate with twointegral connector receptacles. Concealed behind the
mounting plate within the evaporator housing is the
power module electronic circuitry and a large finned,
heat sink. The module mounting plate is secured
with two screws to the rear heater-A/C unit housing
and is accessed for service by removing the right
quarter and D-pillar trim panels.
The power module heat sink will get hot when in
use. Do not touch the heat sink if the blower motor
has been running. The blower power module cannot
be adjusted or repaired and, if faulty or damaged, it
must be replaced.
OPERATION
The blower power module is connected to the vehi-
cle electrical system through a dedicated take out
and connector of the rear HVAC wire harness. A sec-
ond connector receptacle receives the pigtail wire
connector from the blower motor. The blower power
module allows the microprocessor-based Automatic
Temperature Control (ATC) heater-A/C control mod-
ule to calculate and provide infinitely variable blower
motor speeds based upon either manual blower
switch input or the ATC programming using a Pulse
Width Modulated (PWM) circuit strategy. The PWM
Fig. 11 Power Module
1 - REAR HEATER-A/C UNIT HOUSING
2 - SCREW (2)
3 - D-PILLAR
4 - BLOWER PIGTAIL WIRE
5 - REAR HVAC WIRE HARNESS
6 - EXPANSION VALVE
7 - BLOWER POWER MODULE
RSCONTROLS - REAR24-37
MODE DOOR ACTUATOR (Continued)
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