ECU DODGE RAM 1500 1998 2.G Workshop Manual

(10) Install the waterdam. (Refer to 23 - BODY/
DOORS - REAR/WATERDAM - INSTALLATION)
WINDOW REGULATOR -
MANUAL
REMOVAL
(1) Remove the waterdam. (Refer to 23 - BODY/
DOORS - REAR/WATERDAM - REMOVAL)
(2) Reinstall the window handle and raise the win-
dow to the position shown and remove the nuts. (Fig.
11 )
(3) Remove the stabilizer nuts. (Fig. 13)
(4) Disengage the door glass from the regulator lift
plate and position into the full up position.
(5) Secure the glass in the up position using a
wood wedge or equivalent.
(6) Lower the regulator.
(7) Remove the two back regulator bolts and
loosen the front two.
(8) Slide the regulator up and out of the keyhole
slots in the door panel.
(9) Remove the regulator through the hole in the
inner door panel.
INSTALLATION
(1) Install the regulator through the hole in the
inner door panel.
(2) Position the regulator bolts into the keyhole
slots and slide into place.
(3) Install the back regulator bolts and tighten all
four to 10 N´m (89 in. lbs.).
(4) Position the stabilizer, install the nuts and
tighten to 10 N´m (89 in. lbs.).
(5) Using the window handle raise the regulator to
the position shown in (Fig. 11).
(6) Remove the glass support and connect to the
regulator lift plate.
(7) Install the glass nuts and tighten to 10 N´m
(89 in. lbs.).
(8) Disconnect the window switch and install into
the door trim panel.
(9) Using the window handle raise the regulator to
the position shown in (Refer to 23 - BODY/DOORS -
REAR/WATERDAM - INSTALLATION)
Fig. 12 WINDOW REGULATOR MOTOR
1 - REGULATOR BOLTS
2 - REGULATOR MOTOR
3 - ELECTRICAL CONNECTOR.
Fig. 13 WINDOW REGULATOR - MANUAL
1 - DOOR
2 - REGULATOR BOLTS (4)
3 - STABILIZER NUTS (2)
4 - REGULATOR
DRDOORS - REAR 23 - 35
WINDOW REGULATOR - POWER (Continued)

STATIONARY GLASS
TABLE OF CONTENTS
page page
BACKLITE
REMOVAL.............................86
INSTALLATION.........................86
BACKLITE VENT GLASS
REMOVAL.............................87
INSTALLATION.........................87WINDSHIELD
WARNING
WINDSHIELD SAFETY PRECAUTIONS.....88
REMOVAL.............................88
INSTALLATION.........................88
BACKLITE
REMOVAL
It is difficult to salvage the backlite during the
removal operation. The backlite is part of the struc-
tural support for the roof. The urethane bonding
used to secure the glass to the fence is difficult to cut
or clean from any surface. Since the molding is set in
urethane, it is unlikely it would be salvaged. Before
removing the backlite, check the availability from the
parts supplier.
The backlite is attached to the window frame with
urethane adhesive. The urethane adhesive is applied
cold and seals the surface area between the window
opening and the glass. The primer adheres the ure-
thane adhesive to the backlite.
(1) Roll down door glass.
(2) Remove headliner. (Refer to 23 - BODY/INTE-
RIOR/HEADLINER - REMOVAL).
(3) On standard cab models remove the upper
b-pillar trim. (Refer to 23 - BODY/INTERIOR/B-PIL-
LAR UPPER TRIM - REMOVAL)
(4) On quad cab models remove the upper c-pillar
trim. (Refer to 23 - BODY/INTERIOR/C-PILLAR
UPPER TRIM - REMOVAL)
(5) Bend backlite retaining tabs (Fig. 1) inward
against glass.
(6) Disconnect the rear window defogger electrical
connector, if equipped.
(7) Using a suitable pneumatic knife from inside
the vehicle, cut urethane holding backlite frame to
opening fence.
(8) Separate glass from vehicle.
INSTALLATION
(1) Clean urethane adhesive from around backlite
opening fence.
(2) If necessary, apply black-out primer to outer
edge of replacement backlite frame.(3) If black-out primer was pre-applied on backlite,
clean bonding surface with Isopropyl alcohol and
clean lint free cloth. Allow 3 minutes for drying time.
(4) Apply black-out primer to backlite opening
fence.
(5) Apply a 13 mm (0.5 in.) bead of urethane
around the perimeter of the window frame bonding
surface (Fig. 2).
(6) Set glass on lower fence and move glass for-
ward into opening (Fig. 3).
(7) Firmly push glass against rear window glass
opening fence.
(8) Bend tabs around edges of backlite opening
fence to retain glass.
(9) Clean excess urethane from exterior with
MOPARt, Super Clean or equivalent.
(10) Allow urethane to cure at least 24 hours (full
cure is 72 hours).
(11) Water test to verify repair before returning
vehicle to service.
(12) Connect the rear window defogger electrical
connector, if equipped.
Fig. 1 Backlite Tabs
1 - BACKLITE
2-TAB
23 - 86 STATIONARY GLASSDR

The panel outlets receive airflow from the HVAC
housing through a molded plastic main panel duct,
center panel duct and two end panel ducts. The two
end panel ducts direct airflow to the left and right
instrument panel outlets, while the center panel duct
directs airflow to the two center panel outlets. Each
of these outlets can be individually adjusted to direct
the flow of air.
The floor outlets receive airflow from the HVAC
housing through the floor distribution duct. The front
floor outlets are integral to the molded plastic floor
distribution duct, which is secured to the bottom of
the housing. The floor outlets cannot be adjusted.
The air conditioner for all models is designed for
the use of non-CFC, R-134a refrigerant. The air con-
ditioning system has an evaporator to cool and dehu-
midify the incoming air prior to blending it with the
heated air. This air conditioning system uses a fixed
orifice tube in the liquid line near the condenser out-
let tube to meter refrigerant flow to the evaporator
coil. To maintain minimum evaporator temperature
and prevent evaporator freezing, a evaporator tem-
perature sensor is used. The JTEC control module is
programmed to respond to the evaporator tempera-
ture sensor input by cycling the air conditioning com-
pressor clutch as necessary to optimize air
conditioning system performance and to protect the
system from evaporator freezing.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - A/C
PERFORMANCE
The air conditioning system is designed to remove
heat and humidity from the air entering the passen-
ger compartment. The evaporator, located in the
HVAC housing, is cooled to temperatures near the
freezing point. As warm damp air passes over the
fins in the evaporator, moisture in the air condenses
to water, dehumidifying the air. Condensation on the
evaporator fins reduces the evaporators ability to
absorb heat. During periods of high heat and humid-
ity, an air conditioning system will be less effective.
With the instrument control set to Recirculation
mode, only air from the passenger compartment
passes through the evaporator. As the passenger com-
partment air dehumidifies, A/C performance levels
rise.
Humidity has an important bearing on the temper-
ature of the air delivered to the interior of the vehi-
cle. It is important to understand the effect that
humidity has on the performance of the air condition-
ing system. When humidity is high, the evaporator
has to perform a double duty. It must lower the air
temperature, and it must lower the temperature ofthe moisture in the air that condenses on the evapo-
rator fins. Condensing the moisture in the air trans-
fers heat energy into the evaporator fins and tubing.
This reduces the amount of heat the evaporator can
absorb from the air. High humidity greatly reduces
the ability of the evaporator to lower the temperature
of the air.
However, evaporator capacity used to reduce the
amount of moisture in the air is not wasted. Wring-
ing some of the moisture out of the air entering the
vehicle adds to the comfort of the passengers.
Although, an owner may expect too much from their
air conditioning system on humid days. A perfor-
mance test is the best way to determine whether the
system is performing up to standard. This test also
provides valuable clues as to the possible cause of
trouble with the air conditioning system.
PERFORMANCE TEST PROCEDURE
Review Safety Warnings and Cautions before per-
forming this procedure (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - WARNING) and
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - CAUTION). Air temperature in test
room and on vehicle must be 21É C (70É F) minimum
for this test.
NOTE: When connecting the service equipment
coupling to the line fitting, verify that the valve of
the coupling is fully closed. This will reduce the
amount of effort required to make the connection.
(1) Connect a tachometer and a manifold gauge set
or A/C recycling/charging station.
(2) Set the A/C-heater mode control in the Recircu-
lation Mode position, the temperature control knob in
the full cool position, and the blower motor switch to
the highest speed position.
(3) Start the engine and hold at 1,000 rpm with
the A/C compressor clutch engaged.
(4) The engine should be warmed up to operating
temperature with the doors closed and windows
open.
(5) Insert a thermometer in the driver side center
panel A/C-heater outlet and operate the engine for
five minutes.
(6) The compressor clutch may cycle, depending
upon the ambient temperature and humidity.
(7) With the compressor clutch engaged, record the
discharge air temperature and the compressor dis-
charge pressure.
(8) If the discharge air temperature fails to meet
the specifications in the A/C Performance Tempera-
ture chart, refer to the Pressure Diagnosis chart.
DRHEATING & AIR CONDITIONING 24 - 3
HEATING & AIR CONDITIONING (Continued)

CONTROLS
TABLE OF CONTENTS
page page
A/C COMPRESSOR CLUTCH/COIL
DESCRIPTION..........................9
OPERATION............................9
DIAGNOSIS AND TESTING - A/C
COMPRESSOR CLUTCH COIL...........10
STANDARD PROCEDURE - A/C
COMPRESSOR CLUTCH BREAK-IN.......10
REMOVAL.............................10
INSPECTION..........................11
INSTALLATION.........................12
A/C COMPRESSOR CLUTCH RELAY
DESCRIPTION.........................13
OPERATION...........................13
REMOVAL.............................14
INSTALLATION.........................14
A/C HEATER CONTROL
DESCRIPTION.........................14
REMOVAL.............................15
INSTALLATION.........................15
A/C PRESSURE TRANSDUCER
DESCRIPTION.........................15
OPERATION...........................16
DIAGNOSIS AND TESTING - A/C PRESSURE
TRANSDUCER.......................16
REMOVAL.............................16
INSTALLATION.........................16
BLEND DOOR ACTUATOR
DESCRIPTION.........................17
OPERATION...........................17
REMOVAL.............................17
INSTALLATION.........................18
BLOWER MOTOR RESISTOR BLOCK
DESCRIPTION.........................18OPERATION...........................18
DIAGNOSIS AND TESTING - BLOWER
MOTOR RESISTOR BLOCK..............19
REMOVAL.............................19
INSTALLATION.........................19
BLOWER MOTOR SWITCH
DESCRIPTION.........................20
OPERATION...........................20
DIAGNOSIS AND TESTING - BLOWER
MOTOR SWITCH......................20
DEFROST DOOR ACTUATOR
DESCRIPTION.........................20
OPERATION...........................21
REMOVAL.............................21
INSTALLATION.........................21
EVAPORATOR TEMPERATURE SENSOR
DESCRIPTION.........................22
OPERATION...........................22
REMOVAL.............................22
INSTALLATION.........................22
MODE DOOR ACTUATOR
DESCRIPTION.........................23
OPERATION...........................23
REMOVAL.............................23
INSTALLATION.........................23
RECIRCULATION DOOR ACTUATOR
DESCRIPTION.........................24
OPERATION...........................24
REMOVAL.............................24
INSTALLATION.........................25
A/C COMPRESSOR CLUTCH/
COIL
DESCRIPTION
The compressor clutch assembly consists of a sta-
tionary electromagnetic coil, a pulley bearing and
pulley assembly, and a clutch plate (Fig. 1). The elec-
tromagnetic coil and the pulley bearing and pulley
assembly are each retained on the nose of the com-
pressor front housing with snap rings. The clutch
plate is keyed to the compressor shaft and secured
with a nut. These components provide the means toengage and disengage the compressor from the
engine serpentine accessory drive belt.
OPERATION
The A/C compressor clutch provides the means to
engage and disengage the A/C compressor from the
engine serpentine accessory drive belt. When the
clutch coil is energized, it magnetically draws the
clutch into contact with the pulley and drives the
compressor shaft. When the coil is not energized, the
pulley freewheels on the pulley bearing, which is
part of the pulley assembly. The compressor clutch
DRCONTROLS 24 - 9

and coil are the only serviced parts on the compres-
sor.
A/C compressor clutch engagement is controlled by
several components: the A/C-heater control, A/C pres-
sure transducer, A/C compressor clutch relay, evapo-
rator temperature sensor and the powertrain control
module (PCM). The PCM may delay compressor
clutch engagement for up to thirty seconds (Refer to
8 - ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/POWERTRAIN CONTROL MODULE -
DESCRIPTION).
DIAGNOSIS AND TESTING - A/C COMPRESSOR
CLUTCH COIL
For circuit descriptions and diagrams, (Refer to
Appropriate Wiring Information). The battery must
be fully-charged before performing the following
tests. Refer to Battery for more information.
(1) Connect an ammeter (0 to 10 ampere scale) in
series with the clutch coil terminal. Use a voltmeter
(0 to 20 volt scale) with clip-type leads for measuring
the voltage across the battery and the compressor
clutch coil.
(2) With the A/C-heater controls in any A/C mode,
and the blower motor switch in the lowest speed
position, start the engine and run it at normal idle.
(3) The compressor clutch coil voltage should read
within 0.2 volts of the battery voltage. If there is
voltage at the clutch coil, but the reading is not
within 0.2 volts of the battery voltage, test the clutch
coil feed circuit for excessive voltage drop and repair
as required. If there is no voltage reading at the
clutch coil, use a DRB IIItscan tool and (Refer to
Appropriate Diagnostic Information) for testing of thecompressor clutch circuit and PCM control. The fol-
lowing components must be checked and repaired as
required before you can complete testing of the clutch
coil:
²Fuses in the junction block and the power distri-
bution center (PDC)
²A/C-heater control
²A/C compressor clutch relay
²A/C pressure transducer
²Evaporator temperature sensor
²Powertrain control module (PCM)
(4) The compressor clutch coil is acceptable if the
current draw measured at the clutch coil is within
specifications with the electrical system voltage at
11.5 to 12.5 volts (Refer to 24 - HEATING & AIR
CONDITIONING - SPECIFICATIONS). This should
only be checked with the work area temperature at
21É C (70É F). If system voltage is more than 12.5
volts, add electrical loads by turning on electrical
accessories until the system voltage drops below 12.5
volts.
(a) If the clutch coil current reading is above
specifications, the coil is shorted and should be
replaced.
(b) If the clutch coil current reading is zero, the
coil is open and should be replaced.
STANDARD PROCEDURE - A/C COMPRESSOR
CLUTCH BREAK-IN
After a new compressor clutch has been installed,
cycle the compressor clutch approximately twenty
times (five seconds on, then five seconds off). During
this procedure, set the A/C-heater control to the
Recirculation Mode, the blower motor switch in the
highest speed position, and the engine speed at 1500
to 2000 rpm. This procedure (burnishing) will seat
the opposing friction surfaces and provide a higher
compressor clutch torque capability.
REMOVAL
The refrigerant system can remain fully-charged
during compressor clutch, rotor, or coil replacement.
The compressor clutch can be serviced in the vehicle.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the serpentine drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(3) Disconnect the compressor clutch coil wire har-
ness connector.
(4) Remove the bolts that secure the compressor to
the mounting bracket.
(5) Remove the compressor from the mounting
bracket. Support the compressor in the engine com-
partment while servicing the clutch.
Fig. 1 Compressor Clutch - Typical
1 - CLUTCH PLATE
2 - SHAFT KEY (not used on KJ)
3 - ROTOR
4 - COIL
5 - CLUTCH SHIMS
6 - SNAP RING
7 - SNAP RING
24 - 10 CONTROLSDR
A/C COMPRESSOR CLUTCH/COIL (Continued)

The illumination lamps are available for service
replacement.
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 AN ACCIDENTAL
AIRBAG 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 -
REMOVAL).
(3) Remove the screws that secure the A/C-heater
control to the instrument panel (Fig. 14).
INSTALLATION
(1) Position the A/C-heater control onto the instru-
ment panel center bezel and install the retaining
screws. Tighten the screws to 2.2 N´m (20 in. lbs.).
(2) Install the instrument panel center bezel (Refer
to 23 - BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL CENTER BEZEL - INSTALLATION).
(3) Reconnect the battery negative cable.
A/C PRESSURE TRANSDUCER
DESCRIPTION
The A/C pressure transducer is a switch that is
installed on a fitting located on the refrigerant dis-
charge line between the compressor and the con-
denser in the front corner of the engine
compartment. An internally threaded hex fitting on
the transducer connects it to the externally threaded
Schrader-type fitting on the discharge line. A rubber
O-ring seals the connection between the transducer
and the discharge line fitting. Three terminals within
a molded plastic connector receptacle on the top of
the transducer connect it to the vehicle electrical sys-
tem through a wire lead and connector of the head-
lamp and dash wire harness.
Fig. 12 Single Zone HVAC Control
1 - MOUNTING TAB (4)
2 - A/C BUTTON
3 - SIDEVIEW MIRROR DEFROSTER BUTTON (IF EQUIPED)
4 - MODE CONTROL SWITCH
5 - TEMPERATURE CONTROL SWITCH
6 - BLOWER MOTOR SWITCH
Fig. 13 Dual Zone A/C Control
1 - A/C BUTTON
2 - MAX. A/C BUTTON
3 - SIDEVIEW MIRROR DEFROSTER BUTTON (IF EQUIPED)
4 - MOUNTING TABS (4)
5 - DRIVERSIDE TEMPERATURE CONTROL
6 - PASSENGERSIDE TEMPERATURE CONTROL
7 - MODE CONTROL SWITCH
8 - BLOWER MOTOR SWITCH
Fig. 14 A/C-Heater Control - Typical, Rear View
1 - MOUNTING TAB (4)
2 - SCREW (4)
3 - A/C-HEATER CONTROL ELECTRICAL CONNECTOR
4 - HEATED SIDEVIEW MIRROR ELECTRICAL CONNECTOR
5 - A/C-HEATER CONTROL
DRCONTROLS 24 - 15
A/C HEATER CONTROL (Continued)

The A/C pressure transducer cannot be adjusted or
repaired and, if faulty or damaged, it must 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 discharge
line. The transducer will change its internal resis-
tance in response to the pressures it monitors. The
Powertrain Control Module (PCM) or the Engine
Control Module (ECM) depending on engine applica-
tion, provides a five volt reference signal and a sen-
sor ground to the transducer, then monitors the
output voltage of the transducer on a sensor return
circuit to determine refrigerant pressure. The PCM/
ECM is programmed to respond to this and other
sensor inputs by controlling the operation of the air
conditioning compressor clutch and the radiator cool-
ing fan to help optimize air conditioning system per-
formance and to protect the system components from
damage. The A/C pressure transducer input to the
PCM/ECM will also prevent the air conditioning com-
pressor clutch from engaging when ambient temper-
atures are below about 10É C (50É F) due to the
pressure/temperature relationship of the refrigerant.
The Schrader-type valve in the discharge 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 DRBIIItscan tool. Refer to the appropriate
diagnostic information.
DIAGNOSIS AND TESTING - A/C PRESSURE
TRANSDUCER
The A/C pressure transducer is tested using a
DRBIIItscan 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) or Engine Control Module (ECM) depending
on engine application. The PCM/ECM is programmed
to respond to a low or high refrigerant system pres-
sure by suppressing operation of the compressor.
Refer to the A/C Pressure Transducer Voltage chart
for the possible conditions indicated by the trans-
ducer voltage reading.
A/C PRESSURE TRANSDUCER VOLTAGE
CHART
Voltage Possible Indication
0.0 1. No sensor supply voltage from
PCM/ECM.
2. Shorted sensor circuit.
3. Faulty transducer.
0.150 TO 0.450 1. Ambient temperature below
10É C (50É 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: Note: It is not necessary to discharge the
refrigerant system to replace the A/C pressure
transducer.
(1) Disconnect and isolate the battery negative
cable.
(2) Disconnect the wire harness connector from the
A/C pressure transducer.
(3) Remove the A/C pressure transducer from the
fitting on the discharge line (Fig. 15).
(4) Remove the O-ring seal from the A/C pressure
transducer fitting and discard.
INSTALLATION
NOTE: Replace the O-ring seal before installing the
A/C pressure transducer.
(1) Lubricate a new rubber O-ring seal with clean
refrigerant oil and install it on the A/C pressure
transducer fitting. Use only the specified O-rings as
they are made of a special material for the R-134a
system. Use only refrigerant oil of the type recom-
mended for the A/C compressor in the vehicle.
(2) Install and tighten the A/C pressure transducer
onto the discharge line fitting. The transducer should
be hand-tightened securely onto the discharge line
fitting.
(3) Connect the wire harness connector to the A/C
pressure transducer.
24 - 16 CONTROLSDR
A/C PRESSURE TRANSDUCER (Continued)

(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 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 doors, which are controlled by two blend
door actuators. The single zone blend door actuator is
located on the driver side end of the HVAC housing,
close to the dash panel. In the dual zone system, the
same blend door actuator used for the single zone
system becomes the driver side blend door actuator,
and is mechanically connected to only the driver side
blend door. In the dual zone system, a second sepa-
rate blend door actuator is also located on the top of
the HVAC housing and is mechanically connected to
only the passenger side blend door.
The blend door actuators are interchangeable with
each other, as well as with the actuators for the
mode door, defrost door and the recirculation door.
Each actuator is contained within an identical blackmolded plastic housing with an integral wire connec-
tor receptacle. Integral mounting tabs allow the
actuator to be secured with three screws to the
HVAC housing. Each actuator also has an identical
output shaft with splines that connects it to the link-
age that drives the proper door. The blend door
actuators do not require mechanical indexing to the
blend door linkage, as they are electronically cali-
brated 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 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 can be diagnosed using a
DRBIIItscan tool. Refer to Body Diagnostic Proce-
dures for more information. The blend door actuators
cannot be adjusted or repaired and, if damaged or
faulty, they must be replaced.
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.
Fig. 15 A/C Pressure Transducer - 3.7L Shown
1 - NUT
2 - FRONT UPPER CROSSMEMBER
3 - A/C CONDENSER
4 - NUT (2)
5 - SUCTION LINE
6 - A/C COMPRESSOR
7 - A/C PRESSURE TRANSDUCER
8 - WIRE HARNESS CONNECTOR
9 - A/C DISCHARGE LINE
DRCONTROLS 24 - 17
A/C PRESSURE TRANSDUCER (Continued)

NOTE: The single zone heating and air conditioning
system is equipped with a single blend door actua-
tor. 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 procedures can be used for each of
these actuators.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the instrument panel from the vehicle
(Refer to 23 - BODY/INSTRUMENT PANEL/IN-
STRUMENT PANEL ASSEMBLY - REMOVAL).
(3) Disconnect the wire harness connector from the
blend door actuator(s) (Fig. 16).
(4) Remove the screws that secure the blend door
actuator(s) to the HVAC housing.
(5) Remove the blend door actuator(s) from the
HVAC housing.INSTALLATION
(1) Position the blend door actuator(s) into the
HVAC housing. If necessary, rotate the actuator(s)
slightly to align the splines on the actuator output
sleeve(s) with those on the blend door linkage.
(2) Install and tighten the screws that secure the
blend door actuator(s) to the HVAC housing. Tighten
the screws to 2 N´m (17 in. lbs.).
(3) Connect the HVAC wire harness connector to
the blend door actuator(s).
(4) Install the instrument panel (Refer to 23 -
BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL ASSEMBLY - INSTALLATION).
(5) Reconnect the battery negative cable.
BLOWER MOTOR RESISTOR
BLOCK
DESCRIPTION
The blower motor resistor is mounted to the bot-
tom side of the HVAC housing near the blower motor.
It can be accessed for service from underneath the
instrument panel.
OPERATION
The resistor has multiple resistor wires, each of
which will reduce the current flow to the blower
motor to change the blower motor speed by changing
the resistance in the blower motor ground path. The
blower motor switch directs the ground path 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 resis-
tor wires, increasing the blower motor speed. When
the blower motor switch is in the highest speed posi-
tion, the blower motor resistor is bypassed and the
blower motor receives a direct path to ground.
The blower motor resistor cannot be repaired and,
if faulty or damaged, it must be replaced.
Fig. 16 HVAC Housing - Dual Zone Shown, Single
Zone Typical
1 - NUT
2 - PASSENGER BLEND DOOR ACTUATOR
3 - NUT
4 - INLET BAFFLE
5 - RECIRCULATION DOOR ACTUATOR
6 - RECIRCULATION DOOR
7 - DRIVER SIDE BLEND DOOR ACTUATOR
8 - HVAC HOUSING
9 - BOLT
10 - DEFROSTER DOOR ACTUATOR
11 - MODE DOOR ACTUATOR
24 - 18 CONTROLSDR
BLEND DOOR ACTUATOR (Continued)

DIAGNOSIS AND TESTING - BLOWER MOTOR
RESISTOR BLOCK
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 AN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
For circuit descriptions and diagrams, refer to the
appropriate wiring information. The wiring informa-
tion includes wiring diagrams, proper wire and con-
nector repair procedures, further details on wire
harness routing and retention, as well as pin-out and
location views for the various wire harness connec-
tors, splices and grounds.
(1) Disconnect and isolate the negative battery
cable.
(2) Disconnect the wire harness connector from the
blower motor resistor block.
(3) Check for continuity between each of the
blower motor switch input terminals of the resistor
and the resistor output terminal. In each case there
should be continuity. If OK, repair the wire harness
circuits between the blower motor switch and blower
motor resistor or blower motor as required. If not
OK, replace the faulty blower motor resistor block.
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 AN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.CAUTION: Stay clear of the blower motor resistor
block heat sink (Hot). Do not operate the blower
motor with the resistor block removed.
(1) Disconnect and isolate the negative battery
cable.
(2) Reach under the instrument panel near the
blower motor and disconnect the wire harness con-
nector from the blower motor resistor block.
(3) Remove the two screws that secure the blower
motor resistor block to the HVAC housing.
(4) Remove the resistor block from the HVAC
housing.
INSTALLATION
(1) Position the blower motor resistor block into
the HVAC housing.
(2) Install the two screws that secure the resistor
block to the HVAC housing. Tighten the screws to 2.2
N´m (20 in. lbs.).
(3) Connect the wire harness connector to the
resistor block.
(4) Reconnect the battery negative cable.
Fig. 17 Blower Motor Resistor Block
1 - SCREW (2)
2 - WIRE HARNESS CONNECTOR
3 - HVAC HOUSING
4 - BLOWER MOTOR RESISTOR BLOCK
5 - BLOWER MOTOR
DRCONTROLS 24 - 19
BLOWER MOTOR RESISTOR BLOCK (Continued)