Chrysler Pacifica. Manual - part 886

DIAGNOSIS AND TESTING

A/C PRESSURE TRANSDUCER

The A/C pressure transducer is tested using a

DRBIII

t scan tool. Refer to the appropriate diagnos-

tic information. Before testing the A/C pressure
transducer, be certain that the transducer wire har-
ness connection is clean of corrosion and properly
connected. For the A/C to operate, an A/C pressure
transducer voltage reading between 0.451 and 4.519
volts is required. Voltages outside this range indicate
a low or high refrigerant system pressure condition
to the powertrain control module (PCM). The PCM is
programmed to respond to a low or high refrigerant
system pressure by suppressing operation of the A/C
compressor. Refer to the A/C Pressure Transducer
Voltage chart for the possible conditions indicated by
the transducer voltage reading.

A/C PRESSURE TRANSDUCER VOLTAGE

Voltage

Possible Indication

0.0

1. No sensor supply voltage from
PCM.

2. Shorted sensor circuit.

3. Faulty transducer.

0.150 TO 0.450

1. Ambient temperature below
10° C (50° F).

2. Low refrigerant system
pressure.

0.451 TO 4.519

1. Normal refrigerant system
pressure.

4.520 TO 4.850

1. High refrigerant system
pressure.

5.0

1. Open sensor circuit.

2. Faulty transducer.

REMOVAL

NOTE: It is not necessary to discharge the refriger-
ant system to replace the A/C pressure transducer.

(1) Disconnect and isolate the negative battery

cable.

(2) Disconnect the wire harness connector from the

A/C pressure transducer located on the liquid line
(Fig. 12).

(3) Remove the A/C pressure transducer from the

fitting on the liquid line and remove and discard the
O-ring seal.

INSTALLATION

NOTE: Use only the specified O-ring as it is made
of special material for R-134a. Use only refrigerant
oil of the type required for the A/C compressor.

(1) Lubricate a new rubber O-ring seal with clean

refrigerant oil and install it on the liquid line fitting.

(2) Install the A/C pressure transducer onto the liq-

uid line. Tighten the A/C pressure transducer securely.

(3) Connect the wire harness connector to the A/C

pressure transducer.

(4) Reconnect the negative battery cable.

BLEND DOOR ACTUATOR

DESCRIPTION

The two blend door actuators for the dual zone

heating-A/C system are reversible, 12-volt Direct
Current (DC), servo motors (Fig. 13).

For this dual zone heating-A/C system, one blend

door actuator is mechanically connected to only the
driver side blend-air door, while a second separate
blend door actuator is mechanically connected to only
the passenger side blend-air door.

The blend door actuators are interchangeable with

each other, as well as with the actuator for the mode-air
doors and the recirculation-air door. Each actuator is
contained within an identical black molded plastic hous-
ing with an integral wire connector receptacle. Each
actuator also has an identical output shaft with splines
that connects it to its respective door linkage and two
integral mounting tabs that allow the actuator to be

Fig. 12 A/C Pressure Transducer - Typical

1 - RIGHT FRONT STRUT TOWER
2 - WIRE HARNESS CONNECTOR
3 - A/C PRESSURE TRANSDUCER
4 - WIPER MODULE DRAIN TUBE
5 - HIGH SIDE SERVICE PORT
6 - LIQUID LINE

CONTROLS - FRONT

24 - 21

A/C PRESSURE TRANSDUCER (Continued)

secured to the HVAC housing. The blend door actuators
do not require mechanical indexing to the blend-air
doors, as they are electronically calibrated by the A/C-
heater control.

The A/C-heater control must be recalibrated each

time an actuator motor is replaced (Refer to 24 - HEAT-
ING & AIR CONDITIONING/CONTROLS - FRONT/A/C
HEATER CONTROL - STANDARD PROCEDURE -A/C-
HEATER CONTROL CALIBRATION).

OPERATION

Each blend door actuator is connected to the A/C-

heater control through the vehicle electrical system by a
dedicated two-wire lead and connector from the HVAC
wire harness. The blend door actuator can move the
blend-air door in two directions. When the A/C-heater
control pulls the voltage on one side of the motor con-
nection high and the other connection low, the blend-air
door will move in one direction. When the A/C-heater
control reverses the polarity of the voltage to the motor,
the blend-air door moves in the opposite direction.
When the A/C-heater control makes the voltage to both
connections high or both connections low, the blend-air
door stops and will not move. The motor connections
also provide a feedback signal to the A/C-heater control.
This feedback signal allows the A/C-heater control to
monitor the operation and relative positions of the blend
door actuator and the blend-air door. The A/C-heater
control learns the blend door stop positions during the
calibration procedure and will store a diagnostic trouble
code (DTC) for any problems it detects in the blend door
actuator circuits.

The blend door actuator(s) can be diagnosed using

a DRBIII

t scan tool. Refer to Body Diagnostic Proce-

dures for more information.

The blend door actuator(s) cannot be adjusted or

repaired and, if damaged or faulty, they must be
replaced.

REMOVAL

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: 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.

(1) Disconnect and isolate the negative battery

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) Disconnect the wire harness connector from the

blend door actuator being serviced (Fig. 14).

(4) Remove the two screws that secure the blend

door actuator being serviced to the HVAC air distri-
bution housing and remove the actuator.

Fig. 13 Blend Door Actuator

1 - ACTUATOR MOTOR
2 - WIRE CONNECTOR RECEPTACLE
3 - OUTPUT SHAFT
4 - MOUNTING TAB (2)

Fig. 14 Blend Door Actuator

1 - WIRE HARNESS CONNECTOR
2 - MODE DOOR ACTUATOR
3 - SCREW (2)
4 - DRIVER BLEND DOOR ACTUATOR (DUAL-ZONE)
5 - HEATER CORE
6 - BLEND DOOR ACTUATOR

24 - 22

CONTROLS - FRONT

BLEND DOOR ACTUATOR (Continued)

INSTALLATION

(1) Position the blend door actuator being serviced

onto the air distribution 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 the two screws that secure the blend

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

(3) Connect the HVAC wire harness connector to

the blend door actuator being serviced.

(4) Install the silencer under the driver side end of

the instrument panel (Refer to 23 - BODY/INSTRU-
MENT PANEL/INSTRUMENT PANEL SILENCER -
INSTALLATION).

(5) Reconnect the negative battery cable and cali-

brate the A/C-heater control (Refer to 24 - HEATING
& AIR CONDITIONING/CONTROLS - FRONT/A/C
HEATER CONTROL - STANDARD PROCEDURE
-A/C-HEATER CONTROL CALIBRATION).

BLOWER MOTOR POWER
MODULE

DESCRIPTION

A front blower motor power module is used on this

model when it is equipped with the automatic tem-
perature control (ATC) heating-A/C system (Fig. 15).
Models equipped with the manual temperature con-
trol (MTC) heating-A/C system use a blower motor
resistor, instead of the blower motor power module
(Refer to 24 - HEATING & AIR CONDITIONING/
CONTROLS-FRONT/RESISTOR-BLOWER MOTOR -
DESCRIPTION).

The front blower motor power module is mounted

to the rear of the front HVAC housing, directly
behind the glove box. The blower motor power mod-
ule consists of a molded plastic mounting plate with
two integral connector receptacles (1). Concealed
behind the mounting plate is the power module elec-
tronic circuitry and a large finned heat sink (2). The
front blower motor power module is accessed for ser-
vice by removing the glove box.

OPERATION

The front blower motor power module is connected

to the vehicle electrical system through a dedicated
lead and connector of the front HVAC wire harness.
A second connector receptacle receives the wire har-
ness connector from the front blower motor. The front
blower motor power module allows the microproces-
sor-based automatic temperature control (ATC) A/C-
heater control to calculate and provide infinitely
variable blower motor speeds based upon either man-
ual blower switch input or the ATC programming

using a pulse width modulated (PWM) circuit strat-
egy.

The PWM voltage is applied to a comparator cir-

cuit which compares the PWM signal voltage to the
front blower motor feedback voltage. The resulting
output drives the power module circuitry, which pro-
vides a linear output voltage to change or maintain
the desired blower speed.

The front blower motor power module is diagnosed

using a DRBIII

t scan tool. Refer to Body Diagnostic

Procedures.

The front blower motor power module cannot be

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

REMOVAL

Fig. 15 Front Blower Motor Power Module

1 - BLOWER MOTOR POWER MODULE
2 - HEAT SINK

CONTROLS - FRONT

24 - 23

BLEND DOOR ACTUATOR (Continued)

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

(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 power module (Fig. 16).

(4) Remove the two screws that secure the front

blower motor power module to the front HVAC hous-
ing and remove the power module.

INSTALLATION

(1) Position the front blower motor power module

into the front HVAC housing.

(2) Install the two screws that secure the front

blower motor power module to the front HVAC hous-
ing. Tighten the screws to 2 N·m (17 in. lbs.).

(3) Connect the two wire connectors to the front

blower motor power module.

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

STRUMENT PANEL/GLOVE BOX - INSTALLA-
TION).

(5) Reconnect the negative battery cable.

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
integrated power module (IPM) to control the high
current 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 IPM. The inputs and outputs of the blower motor
relay include:

Fig. 16 Front Blower Motor Power Module

1 - FRONT BLOWER MOTOR POWER MODULE
2 - LOWER GLOVE BOX OPENING REINFORCEMENT
3 - FRONT HVAC HOUSING

Fig. 17 Front Blower Motor Relay

COMMON FEED

COIL BATTERY

COIL GROUND

NORMALLY OPEN

87A

NORMALLY CLOSED

24 - 24

CONTROLS - FRONT

BLOWER MOTOR POWER MODULE (Continued)

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