ECU DODGE RAM 2003 Service Repair Manual

CONTROLS
TABLE OF CONTENTS
page page
A/C COMPRESSOR CLUTCH
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..........................12
INSTALLATION.........................12
A/C COMPRESSOR CLUTCH RELAY
DESCRIPTION.........................13
OPERATION...........................13
DIAGNOSIS AND TESTING - COMPRESSOR
CLUTCH RELAY......................13
REMOVAL.............................14
INSTALLATION.........................14
A/C HEATER CONTROL
DESCRIPTION.........................14
REMOVAL.............................14
INSTALLATION.........................15
A/C PRESSURE TRANSDUCER
DESCRIPTION - A/C PRESSURE
TRANSDUCER.......................15
OPERATION...........................15
DIAGNOSIS AND TESTING - A/C PRESSURE
TRANSDUCER.......................15
REMOVAL.............................16
INSTALLATION.........................16
BLEND DOOR ACTUATOR
DESCRIPTION.........................16
OPERATION...........................16REMOVAL.............................17
INSTALLATION.........................17
BLOWER MOTOR RESISTOR BLOCK
DESCRIPTION.........................17
OPERATION...........................17
DIAGNOSIS AND TESTING - BLOWER
MOTOR RESISTOR....................18
REMOVAL.............................18
INSTALLATION.........................18
BLOWER MOTOR SWITCH
DESCRIPTION.........................18
OPERATION...........................18
DIAGNOSIS AND TESTING - BLOWER
MOTOR SWITCH......................18
REMOVAL.............................19
INSTALLATION.........................19
DEFROST DOOR ACTUATOR
REMOVAL - FLOOR - DEFROST DOOR
ACTUATOR..........................19
INSTALLATION - FLOOR - DEFROST DOOR
ACTUATOR..........................20
MODE DOOR ACTUATOR
DESCRIPTION.........................20
OPERATION...........................21
REMOVAL.............................21
INSTALLATION.........................22
RECIRCULATION DOOR ACTUATOR
DESCRIPTION.........................22
OPERATION...........................22
REMOVAL.............................22
INSTALLATION.........................23
A/C COMPRESSOR CLUTCH
DESCRIPTION
The compressor clutch assembly consists of a sta-
tionary electromagnetic coil, a rotor bearing and
rotor assembly, and a clutch plate (Fig. 1). The elec-
tromagnetic coil unit and the rotor bearing and rotor
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 to
engage and disengage the compressor from the
engine serpentine accessory drive belt.
OPERATION
When the clutch coil is energized, it magnetically
draws the clutch into contact with the rotor and
drives the compressor shaft. When the coil is not
energized, the rotor freewheels on the clutch rotor
bearing, which is part of the rotor. The compressor
clutch and coil are the only serviced parts on the
compressor.
The compressor clutch engagement is controlled by
several components: the A/C Heater mode control
switch, the A/C high pressure transducer, the com-
pressor clutch relay, and the (JTEC). The JTEC may
delay compressor clutch engagement for up to thirty
DRCONTROLS 24 - 9

seconds. Refer to Electronic Control Modules for
more information on the JTEC controls.
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 mode control switch 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 the
compressor 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 Dis-
tribution Center (PDC)
²A/C heater mode control switch
²Compressor clutch relay
²A/C high pressure transducer switch²JTEC
(4) The compressor clutch coil is acceptable if the
current draw measured at the clutch coil is 2.0 to 3.9
amperes with the electrical system voltage at 11.5 to
12.5 volts. 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 turn-
ing on electrical accessories until the system voltage
drops below 12.5 volts.
(a) If the clutch coil current reading is four
amperes or more, 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) Unplug the compressor clutch coil wire harness
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.
(6) Insert the two pins of the spanner wrench
(Special Tool C-4489 or equivalent) into the holes of
the clutch plate. Hold the clutch plate stationary and
remove the hex nut (Fig. 2).
(7) Remove the clutch plate.
(8) Remove the compressor clutch shims.
(9) Remove the external front housing snap ring
with snap ring pliers (Fig. 3).
(10)
Install the lip of the rotor puller (Special Tool
C-6141-1 or equivalent) into the snap ring groove
exposed in the previous step, and install the shaft pro-
tector (Special Tool C-6141-2 or equivalent) (Fig. 4).
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 (Continued)

for relay terminal 86 with the ignition switch in the
On position. If OK, go to Step 5. If not OK, repair the
open circuit to the fuse in the junction block as
required.
(5) The coil ground terminal cavity (85) is switched
to ground through the Powertrain Control Module
(PCM). There should be continuity between this cav-
ity and the A/C compressor clutch relay control cir-
cuit cavity of the PCM wire harness connector C
(gray) at all times. If not OK, repair the open circuit
as required.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the cover from the Power Distribution
Center (PDC).
(3) Refer to the label on the PDC for compressor
clutch relay identification and location.
(4) Unplug the compressor clutch relay from the
PDC.
INSTALLATION
(1) Install the compressor clutch relay by aligning
the relay terminals with the cavities in the PDC and
pushing the relay firmly into place.
(2) Install the PDC cover.
(3) Connect the battery negative cable.
(4) Test the relay operation.
A/C HEATER CONTROL
DESCRIPTION
The A/C heater system uses a seriers of electrical
controls. These controls provide the vehicle operator
with a number of setting options to help control the
climate and comfort within the vehicle. Refer to the
owner's manual in the vehicle glove box for more
information on the features, use, and suggested oper-
ation of these controls.
The A/C heater control - (Single Zone) or (Dual
Zone) panel is located to the right of the instrument
cluster on the instrument panel.
The control panel contains a rotary-type tempera-
ture control, a rotary-type mode control switch knob,
and a rotary-type blower motor speed switch knob.
The control also has a push button to activate the
Optional side view mirrors defroster elements and to
turn the A/C on.
The Dual Zone HVAC control panel contains a pair
of slider-type temperature controls, a rotary-type
mode control switch knob and a rotary-type blower
motor speed switch knob. The control also has but-
tons to turn the A/C ON, Set it on Max A/C and for
the Optional Heated Sideview Mirrors.The A/C heater control panel cannot be repaired. If
faulty or damaged, the entire unit must be replaced.
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/IN-
STRUMENT PANEL CENTER BEZEL - REMOVAL).
(3) Remove the screws that secure the A/C Heater
control to the instrument panel (Fig. 11) or (Fig. 12).
(4) Pull the A/C Heater control assembly away
from the instrument panel far enough to access the
connections on the back of the control.
(5) Unplug the wire harness connectors from the
back of the A/C Heater control (Fig. 13).
Fig. 11 Single Zone HVAC Control
1 - Mounting Tab (4)
2 - A/C Button
3 - Sideview Mirror Defroster Button (if equiped)
4 - Mode Control
5 - Blend Air Control
6 - Blower Motor Speed Control
24 - 14 CONTROLSDR
A/C COMPRESSOR CLUTCH RELAY (Continued)

INSTALLATION
(1) Plug the two wire harness connectors into the
back of the A/C Heater control.
(2) Position the A/C Heater control in the instru-
ment panel bezel and secure it with four screws.
Tighten the screws to 2.2 N´m (20 in. lbs.).
(3) Reinstall the center bezel onto the instrument
panel(Refer to 23 - BODY/INSTRUMENT PANEL/IN-
STRUMENT PANEL CENTER BEZEL - INSTALLA-
TION).
(4) Connect the battery negative cable.
A/C PRESSURE TRANSDUCER
DESCRIPTION - A/C PRESSURE TRANSDUCER
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 conden-
sor in the front corner of the engine compartment. An
internally threaded hex fitting on the transducer con-
nects it to the externally threaded Schrader-type fit-
ting on the liquid 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 con-
nect 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 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) provides a five
volt reference 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 components from damage. The A/C pres-
sure transducer input to the PCM will also prevent
the air conditioning compressor clutch from engaging
when ambient temperatures are below about 10É C
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 refriger-
ant 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,
Fig. 12 Dual Zone A/C Control
1 - A/C Button
2 - Max. A/C Button
3 - Sideview Mirror Defrost Button (if equiped)
4 - Mounting Tabs (4)
5 - Driverside Temperature Control
6 - Passengerside Temperature Control
7 - Mode Control
8 - Blower Motor Speed Control
Fig. 13 HVAC Control - (Rear View- typical)
1 - Mounting Tabs (4)
2 - Mounting Screws (4)
3 - HVAC Control Connector
4 - Heated Sideview Mirror Connector
5 - HVAC Control Assembly
DRCONTROLS 24 - 15
A/C HEATER CONTROL (Continued)

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 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
(1) Disconnect and isolate the battery negative
cable.
(2) Disconnect the wire harness connector for the
A/C pressure transducer from the transducer connec-
tor receptacle.
(3) Using an open end wrench, unscrew the A/C
pressure transducer from the fitting on the discharge
line between the compressor and the condenser.
(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
discharge line between the compressor and the con-
denser.
(3) Reconnect the 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 driver side
blend door actuator, and is mechanically connected to
only the driver side blend air door. In the dual zone
system, a second separate blend door actuator is also
located on the top of the heater-A/C housing unit and
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 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-
24 - 16 CONTROLSDR
A/C PRESSURE TRANSDUCER (Continued)

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 DRBIIItscan
tool. Refer to the appropriate diagnostic information.
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 instrument panel assembly(Refer
to 23 - BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL ASSEMBLY - REMOVAL).
(3) Disconnect the HVAC wire harness connector
for the blend door actuator from the actuator connec-
tor receptacle. (Fig. 14)
(4) Remove the screws that secure the blend door
actuator to the distribution housing.
(5) Remove the blend door actuator from the dis-
tribution housing.
INSTALLATION
(1) Position the blend door actuator into 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 three 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) Install the instrument panel assembly(Refer to
23 - BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL ASSEMBLY - 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).BLOWER MOTOR RESISTOR
BLOCK
DESCRIPTION
The blower motor resistor is mounted to the rear
side of the HVAC housing on the passenger side of
the vehicle.
OPERATION
The resistor is a ceramic resistor that utilizes
resistor circuit tracers to reduce current flow to the
Fig. 14 HVAC Housing - Dual Zone Shown (Typical -
Single Zone)
1 - Mounting Nut
2 - Passenger Blend Door Actuator (dual zone)
3 - Mounting Nut
4 - Air Intake Spacer
5 - Recirculation Door Actuator
6 - Recirculation Door Assembly
7 - Driver Side Blend Door Actuator
8 - HVAC Housing
9 - Mounting Screw
10 - Defroster Door Actuator
11 - Panel Actuator
DRCONTROLS 24 - 17
BLEND DOOR ACTUATOR (Continued)

blower. The blower motor switch directs the ground
path through the correct resistor circuit to obtain the
selected speed.
The blower motor resistor cannot be repaired and,
if faulty or damaged, it must be replaced.
DIAGNOSIS AND TESTING - BLOWER MOTOR
RESISTOR
For circuit descriptions and diagrams, (Refer to
Appropriate Wiring Information).
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) Reach under the passenger side bottom of the
HVAC unit and unplug the wire harness connector
from the blower motor resistor.
(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 the
blower motor resistor or blower motor relay as
required. If not OK, replace the faulty blower motor
resistor.
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) The blower motor resistor is accessable from
the passenger side of the HVAC unit and is located
on the bottom of the HVAC unit.
(3) Pull out the lock on the blower motor resistor
wire harness connector to unlock the connector latch.
(4) Depress the latch on the blower motor resistor
wire harness connector and unplug the connector
from the resistor.
(5) Remove the two screws that secure the resistor
to the HVAC housing.
(6) Remove the resistor from the HVAC housing.
INSTALLATION
(1) Install the new resistor in the HVAC housing.
(2) Install the two screws that secure the resistor
to the HVAC housing and tighten to 2.2 N´m (20 in.
lbs.).
(3) Plug in the blower motor harness connector.
(4) Push in the lock on the blower motor resistor
harness connector.
(5) Close the glove box door.
(6) Connect the battery negative cable.
BLOWER MOTOR SWITCH
DESCRIPTION
The A/C Heater blower motor is controlled by a
four position rotary-type blower motor switch,
mounted in the A/C Heater control panel. The switch
allows the selection of one of four blower motor
speeds, but can only be turned off by selecting the
Off position on the blower motor switch.
OPERATION
The blower motor switch directs the blower motor
ground path through the mode control switch to the
blower motor resistor, or directly to ground, as
required to achieve the selected blower motor speed.
The blower motor switch cannot be repaired and, if
faulty or damaged, the entire A/C Heater control unit
must be replaced.
DIAGNOSIS AND TESTING - BLOWER MOTOR
SWITCH
For circuit descriptions and diagrams, (Refer to
Appropriate Wiring Information).
24 - 18 CONTROLSDR
BLOWER MOTOR RESISTOR BLOCK (Continued)

(4) Remove the mounting screws from the actua-
tor.
(5) Remove the actuator from the HVAC housing.
INSTALLATION - FLOOR - DEFROST DOOR
ACTUATOR
(1) Install the floor-defrost door actuator to the
HVAC assembly.
(2) Install the mounting screws and tighten to 2.2
N´m (20 in. lbs.).
(3) Install the actuator electrical connector.
(4) Install the instrument panel assembly into the
vehicle(Refer to 23 - BODY/INSTRUMENT PANEL/
INSTRUMENT PANEL ASSEMBLY - INSTALLA-
TION).
(5) Connect the battery negative cable.
MODE DOOR ACTUATOR
DESCRIPTION
The mode door actuator is a reversible, 12-volt
Direct Current (DC), servo motor (Fig. 16). 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
it to the linkage that drives the mode door. The mode
door actuator does not require mechanical indexing
Fig. 15 HVAC Housing - Dual Zone Shown (Typical -
Single Zone)
1 - Mounting Nut
2 - Passenger Blend Door Actuator (dual zone)
3 - Mounting Nut
4 - Air Intake Spacer
5 - Recirculation Door Actuator
6 - Recirculation Door Assembly
7 - Driver Side Blend Door Actuator
8 - HVAC Housing
9 - Mounting Screw
10 - Defroster Door Actuator
11 - Panel Actuator
Fig. 16 HVAC Housing - Dual Zone Shown (Typical-
Single Zone)
1 - Mounting Nut
2 - Passenger Blend Door Actuator (dual zone)
3 - Mounting Nut
4 - Air Intake Spacer
5 - Recirculation Door Actuator
6 - Recirculation Door Assembly
7 - Driver Side Blend Door Actuator
8 - HVAC Housing
9 - Mounting Screw
10 - Defroster Door Actuator
11 - Panel Actuator
24 - 20 CONTROLSDR
DEFROST DOOR ACTUATOR (Continued)

to the mode door linkage, as it is electronically cali-
brated by the heater-A/C control module. The mode
door actuator cannot be adjusted or repaired and, if
damaged or faulty, it must be replaced.
OPERATION
The mode door actuator is connected to the heater-
A/C control module through the vehicle electrical sys-
tem by a dedicated two-wire take out and connector
of the HVAC wire harness. The mode door actuator
can move the mode door in two directions. When the
heater-A/C control module pulls the voltage on one
side of the motor connection high and the other con-
nection low, the mode door will move in one direction.
When the module reverses the polarity of the voltage
to the motor, the mode door moves in the opposite
direction. When the module makes the voltage to
both connections high or both connections low, the
mode door stops and will not move. These same
motor connections also provide a feedback signal to
the heater-A/C control module. This feedback signal
allows the module to monitor the operation and rela-
tive position of the mode door actuator and the mode
door. The heater-A/C control module learns the mode
door stop positions during the calibration procedure
and will store a Diagnostic Trouble Code (DTC) for
any problems it detects in the mode door actuator
circuits. The mode 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) Remove the instrument panel assembly(Refer
to 23 - BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL ASSEMBLY - REMOVAL).
(3) Disconnect the electricial connector from the
actuator (single or dual zone as required).
(4) Remove the two screws that secure the mode
door actuators to the distribution housing. For singlezone systems only lower actuator in present. For dual
zone systems remove second actuator which is
mounted on top of HVAC housing (Fig. 17).
(5) Remove the mode door actuators from the dis-
tribution housing.
Fig. 17 HVAC Housing - Dual Zone Shown (Typical -
Single Zone)
1 - Mounting Nut
2 - Passenger Blend Door Actuator (dual zone)
3 - Mounting Nut
4 - Air Intake Spacer
5 - Recirculation Door Actuator
6 - Recirculation Door Assembly
7 - Driver Side Blend Door Actuator
8 - HVAC Housing
9 - Mounting Screw
10 - Defroster Door Actuator
11 - Panel Actuator
DRCONTROLS 24 - 21
MODE DOOR ACTUATOR (Continued)

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 mode door actuators onto the heat-
er/AC housing. If necessary, rotate the actuator
slightly to align the splines on the actuator output
shaft with those in the mode door linkage.
(2) Install and tighten the two screws that secure
the mode door actuators 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 actuators to the actuator connector
receptacle.
(4) Install the instrument panel assembly(Refer to
23 - BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL ASSEMBLY - 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).
RECIRCULATION DOOR
ACTUATOR
DESCRIPTION
The recirculation door actuator is a reversible,
12-volt Direct Current (DC), servo motor. The single
recirculation door actuator is located on the passen-
ger side end of the heater-A/C housing unit. The
recirculation door actuator is mechanically connected
to the recirculation air door. The recirculation door
actuator is interchangeable with the actuators for the
blend air door(s) and the mode doors. 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 intake air housing.
Each actuator also has an identical output shaft with
splines that connects it to the linkage that drives therecirculation air door. The recirculation door actuator
does not require mechanical indexing to the recircu-
lation air door, as it is electronically calibrated by the
heater-A/C control module. The recirculation door
actuator cannot be adjusted or repaired and, if dam-
aged or faulty, it must be replaced.
OPERATION
The recirculation door actuator is connected to the
heater-A/C control module through the vehicle elec-
trical system by a dedicated two-wire take out and
connector of the HVAC wire harness. The recircula-
tion door actuator can move the recirculation door in
two directions. When the heater-A/C control module
pulls the voltage on one side of the motor connection
high and the other connection low, the recirculation
air door will move in one direction. When the module
reverses the polarity of the voltage to the motor, the
recirculation air door moves in the opposite direction.
When the module makes the voltage to both connec-
tions high or both connections low, the recirculation
air door stops and will not move. These same motor
connections also provide a feedback signal to the
heater-A/C control module. This feedback signal
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.
24 - 22 CONTROLSDR
MODE DOOR ACTUATOR (Continued)