brated each time an actuator motor or the control
module is replaced. If the vehicle is so equipped, the
calibration procedure also includes rear HVAC posi-
tions for each actuator motor.

(1) Turn the ignition switch to the On position.
(2) Simultaneously depress and hold the Power

and Recirculation buttons on the heater-A/C control
for at least five seconds. The manual heater-A/C con-
trol power Light Emitting Diode (LED) and Recircu-
lation LED, or the Automatic Temperature Control

24 - 8

CONTROLS - FRONT

(ATC) heater-A/C control Delay and Recirculation
graphics will begin to flash when the calibration pro-
cedure has begun.

(3) The calibration procedure should take less than

two minutes to complete for the manual heater-A/C
control, and less than twenty seconds for the ATC
heater-A/C control. When the LEDs or graphics stop
flashing, the calibration procedure is complete.

(4) If the LEDs or graphics continue to flash

beyond the normal three minute (manual) or twenty
second (ATC) calibration time, it indicates that the
heater-A/C control has detected a failure and a Diag-
nostic Trouble Code (DTC) has been set. Use a
DRBIII

t scan tool to perform further diagnosis. Refer

to the appropriate diagnostic information. The LEDs
or graphics will continue to flash even after the igni-
tion switch is cycled Off and On, until a successful
calibration is completed or until the vehicle has been
driven about 13 kilometers (8 miles).

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) Remove the center bezel from the instrument

panel. (Refer to 23 - BODY/INSTRUMENT PANEL/
INSTRUMENT PANEL CENTER BEZEL - REMOV-
AL).

(3) Place the instrument panel center bezel unit

face down on a suitable work surface. Take the
proper precautions to protect the center bezel from
cosmetic damage.

(4) If the vehicle is equipped with the optional

Automatic Temperature Control (ATC) system, dis-
connect the infrared sensor jumper harness connector
from the receptacle on the back of the heater-A/C
control (Fig. 1).

(5) Remove the six screws that secure the heater-

A/C control to the back of the instrument panel cen-
ter bezel.

(6) Remove the heater-A/C control from the instru-

ment panel center bezel.

INSTALLATION

(1) Position the heater-A/C control onto the back of

instrument panel center bezel.

(2) Install and tighten the six screws that secure

the heater-A/C control to the back of the instrument
panel center bezel. Tighten the screws to 2 N·m (17
in. lbs.).

(3) If the vehicle is equipped with the optional

ATC system, reconnect the infrared sensor jumper
harness connector to the receptacle on the back of
the heater-A/C control.

(4) Reinstall the center bezel onto the instrument

panel. (Refer to 23 - BODY/INSTRUMENT PANEL/
INSTRUMENT PANEL CENTER BEZEL - INSTAL-
LATION).

(5) Reconnect the battery negative cable.

Fig. 1 Heater-A/C Control

1 - INFRARED SENSOR JUMPER CONNECTOR (ATC ONLY)
2 - INFRARED SENSOR JUMPER HARNESS (ATC ONLY)
3 - HEATER-A/C CONTROL
4 - SCREW (6)
5- INSTRUMENT PANEL CENTER BEZEL

CONTROLS - FRONT

24 - 9

A/C HEATER CONTROL (Continued)

A/C PRESSURE TRANSDUCER

DESCRIPTION - A/C PRESSURE TRANSDUCER

The A/C pressure transducer (Fig. 2) is a switch

that is installed on a fitting located on the refriger-
ant liquid line between the filter-drier and the
expansion valve in the right rear corner of the engine
compartment. An internally threaded hex fitting on
the transducer connects it to the externally threaded
Schrader-type fitting on the liquid line. A rubber
O-ring seals the connection between the transducer
and the liquid line fitting. Three terminals within a
molded plastic connector receptacle on the top of the
transducer connect it to the vehicle electrical system
through a take out and connector of the headlamp
and dash wire harness.

The A/C pressure transducer cannot be adjusted or

repaired and, if faulty or damaged, it musty be
replaced.

OPERATION

The A/C pressure transducer monitors the pres-

sures in the high side of the refrigerant system
through its connection to a fitting on the liquid line.
The transducer will change its internal resistance in
response to the pressures it monitors. The Power-
train Control Module (PCM) provides a five volt ref-
erence signal and a sensor ground to the transducer,
then monitors the output voltage of the transducer
on a sensor return circuit to determine refrigerant
pressure. The PCM is programmed to respond to this
and other sensor inputs by controlling the operation
of the air conditioning compressor clutch and the

radiator cooling fan to help optimize air conditioning
system performance and to protect the system com-
ponents from damage. The A/C pressure transducer
input to the PCM will also prevent the air condition-
ing compressor clutch from engaging when ambient
temperatures are below about 10° C (50° F) due to
the pressure/temperature relationship of the refriger-
ant. The Schrader-type valve in the liquid line fitting
permits the A/C pressure transducer to be removed
or installed without disturbing the refrigerant in the
system. The A/C pressure transducer is diagnosed
using a DRBIII

t scan tool. Refer to the appropriate

diagnostic information.

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 air conditioning system 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 compressor. Refer to the A/C Pres-
sure Transducer Voltage table for the possible condi-
tion indicated by the transducer voltage readings.

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

(1) Disconnect and isolate the battery negative

cable.

Fig. 2 A/C Pressure Transducer

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

24 - 10

CONTROLS - FRONT

(2) Disconnect the headlamp and dash wire har-

ness connector for the A/C pressure transducer from
the transducer connector receptacle (Fig. 3).

(3) Using an open end wrench, unscrew the A/C

pressure transducer from the fitting on the liquid
line between the filter-drier and the expansion valve.

(4) Remove the seal from the A/C pressure trans-

ducer fitting and discard.

INSTALLATION

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

refrigerant oil and install it on the A/C pressure
transducer fitting.

(2) Using an open end wrench, install and tighten

the A/C pressure transducer onto the fitting on the
liquid line between the filter-drier and the expansion
valve.

(3) Reconnect the headlamp and dash wire harness

connector for the A/C pressure transducer to the
transducer connector receptacle.

(4) Reconnect the battery negative cable.

BLEND DOOR ACTUATOR

DESCRIPTION

The blend door actuators are reversible, 12-volt

Direct Current (DC), servo motors. Models with the
single zone heater and air conditioner system have a
single blend air door, which is controlled by a single
blend door actuator. Models with the optional dual
zone front heater and air conditioner system have
dual blend air doors, which are controlled by two

blend door actuators. The single zone blend door
actuator is located on the driver side end of the heat-
er-A/C housing unit, close to the dash panel. In the
dual zone system, the same blend door actuator used
for the single zone system becomes the passenger
blend door actuator, and is mechanically connected to
only the passenger side blend air door. In the dual
zone system, a second separate blend door actuator is
also located on the driver side end of the heater-A/C
housing unit close to the instrument panel, and is
mechanically connected to only the driver side blend
air door.

The blend door actuators are interchangeable with

each other, as well as with the actuators for the
mode door and the recirculation air door. Each actua-
tor 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 it to the link-
age that drives the proper blend air door. The blend
door actuators do not require mechanical indexing to
the blend door linkage, as they are electronically cal-
ibrated by the heater-A/C control module. The blend
door actuators cannot be adjusted or repaired and, if
damaged or faulty, they must be replaced.

OPERATION

Each blend door actuator is connected to the heat-

er-A/C control module through the vehicle electrical
system by a dedicated two-wire take out and connec-
tor of the HVAC wire harness. The blend door actua-
tor can move the blend air door in two directions.
When the heater-A/C control module pulls the volt-
age on one side of the motor connection high and the
other connection low, the blend air door will move in
one direction. When the module reverses the polarity
of the voltage to the motor, the blend air door moves
in the opposite direction. When the module makes
the voltage to both connections high or both connec-
tions low, the blend air door stops and will not move.
These same motor connections also provide a feed-
back signal to the heater-A/C control module. This
feedback signal allows the module to monitor the
operation and relative positions of the blend door
actuator and the blend air door. The heater-A/C con-
trol module learns the blend air 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 can be diagnosed using a DRBIII

t scan

tool. Refer to the appropriate diagnostic information.

Fig. 3 A/C Pressure Transducer

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

CONTROLS - FRONT

24 - 11

A/C PRESSURE TRANSDUCER (Continued)

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