1998 DODGE RAM 1500 Component and system index

GROUP TAB LOCATOR
Introduction
0Lubrication & Maintenance
2Suspension
3Differential & Driveline
5Brakes
6Clutch
7Cooling
8AAudio/Video
8BChime/Buzzer
8EElectronic Control Modules
8FEngine Systems
8GHeated Systems
8HHorn
8IIgnition Control
8JInstrument Cluster
8LLamps
8MMessage Systems
8NPower Systems
8ORestraints
8PSpeed Control
8QVehicle Theft Security
8RWipers/Washers
8TNavigation/Telecommunication
8WWiring
9Engine
11Exhaust System
13Frame & Bumpers
14Fuel System
19Steering
21Transmission and Transfer Case
22Tires/Wheels
23Body
24Heating & Air Conditioning
25Emissions Control
Component and System Index
Service Manual Comment Forms (Rear of Manual)

DIAGNOSIS AND TESTING - RADIATOR
CAP................................58
CLEANING............................59
INSPECTION..........................59
WATER PUMP - 3.7L/4.7L
DESCRIPTION
DESCRIPTION - WATER PUMP...........59
DESCRIPTION - WATER PUMP BYPASS....59
OPERATION
OPERATIONÐWATER PUMP............60
OPERATION - WATER PUMP BYPASS.....60
REMOVAL.............................60
CLEANING............................61
INSPECTION..........................61
INSTALLATION.........................61
WATER PUMP - 5.9L DIESEL
DESCRIPTION.........................62OPERATION...........................62
DIAGNOSIS AND TESTINGÐWATER PUMP . . . 62
REMOVAL.............................62
CLEANING............................62
INSPECTION..........................62
INSTALLATION.........................62
WATER PUMP - 5.7L
REMOVAL.............................63
INSTALLATION.........................63
WATER PUMP - 8.0L
DIAGNOSIS AND TESTING - WATER PUMP . . . 63
REMOVAL.............................64
CLEANING............................66
INSPECTION..........................66
INSTALLATION.........................66
COOLANT
DESCRIPTION
DESCRIPTION - ENGINE COOLANT
ETHYLENE-GLYCOL MIXTURES
CAUTION: Richer antifreeze mixtures cannot be
measured with normal field equipment and can
cause problems associated with 100 percent ethyl-
ene-glycol.
The use of aluminum cylinder blocks, cylinder
heads and water pumps requires special corrosion
protection. Only MopartAntifreeze/Coolant, 5
year/100,000 Mile Formula (ethylene-glycol base cool-
ant with corrosion inhibitors called HOAT, for Hybrid
Additive Technology) is recommended. This coolant
offers the best engine cooling without corrosion when
mixed with 50% distilled water to obtain a freeze
point of -37ÉC (-35ÉF).
The required ethylene-glycol (antifreeze) and water
mixture depends upon the climate and vehicle oper-
ating conditions. The antifreeze concentrationmust
alwaysbe a minimum of 44 percent, year-round in
all climates.If percentage is lower than 44 per-
cent, engine parts may be eroded by cavitation,
and cooling system components may be
severely damaged by corrosion.Maximum protec-
tion against freezing is provided with a 68% anti-
freeze concentration, which prevents freezing down to
-67.7É C (-90É F). A higher percentage will freeze at a
warmer temperature. Also, a higher percentage of
antifreeze can cause the engine to overheat becausethe specific heat of antifreeze is lower than that of
water.
Use of 100 percent ethylene-glycol will cause for-
mation of additive deposits in the system, as the cor-
rosion inhibitive additives in ethylene-glycol require
the presence of water to dissolve. The deposits act as
insulation, causing temperatures to rise to as high as
149É C (300É F). This temperature is hot enough to
melt plastic and soften solder. The increased temper-
ature can result in engine detonation. In addition,
100 percent ethylene-glycol freezes at 22É C (-8É F ).
PROPYLENE-GLYCOL MIXTURES
It's overall effective temperature range is smaller
than that of ethylene-glycol. The freeze point of 50/50
propylene-glycol and water is -32É C (-26É F). 5É C
higher than ethylene-glycol's freeze point. The boiling
point (protection against summer boil-over) of propy-
lene-glycol is 125É C (257ÉF)at96.5 kPa (14 psi),
compared to 128É C (263É F) for ethylene-glycol. Use
of propylene-glycol can result in boil-over or freeze-up
on a cooling system designed for ethylene-glycol. Pro-
pylene glycol also has poorer heat transfer character-
istics than ethylene glycol. This can increase cylinder
head temperatures under certain conditions.
Propylene-glycol/ethylene-glycol Mixtures can
cause the destabilization of various corrosion inhibi-
tors, causing damage to the various cooling system
components. Also, once ethylene-glycol and propy-
lene-glycol based coolants are mixed in the vehicle,
conventional methods of determining freeze point will
not be accurate. Both the refractive index and spe-
cific gravity differ between ethylene glycol and propy-
lene glycol.
DRENGINE 7 - 31

receptacles that face the instrument panel, while the
inner end of the tape terminates at the pigtail wires
and connector receptacles on the hub of the clock-
spring rotor that face the steering wheel.
Service replacement clocksprings are shipped pre-
centered and with a molded plastic locking pin that
snaps into a receptacle on the rotor and is engaged
between two tabs on the upper surface of the rotor
case. The locking pin secures the centered clock-
spring rotor to the clockspring case during shipment
and handling, but must be removed from the clock-
spring after it is installed on the steering column.
(Refer to 8 - ELECTRICAL/RESTRAINTS/CLOCK-
SPRING - STANDARD PROCEDURE - CLOCK-
SPRING CENTERING).
The clockspring cannot be repaired. If the clock-
spring is faulty, damaged, or if the driver airbag has
been deployed, the clockspring must be replaced.
OPERATION
The clockspring is a mechanical electrical circuit
component that is used to provide continuous electri-
cal continuity between the fixed instrument panel
wire harness and the electrical components mounted
on or in the rotating steering wheel. On this model
the rotating electrical components include the driver
airbag, the horn switch, the speed control switches,
and the remote radio switches, if the vehicle is so
equipped. The clockspring case is positioned and
secured to the multi-function switch mounting hous-
ing near the top of the steering column. The connec-
tor receptacles on the tail of the fixed clockspring
case connect the clockspring to the vehicle electrical
system through two take outs with connectors from
the instrument panel wire harness.The clockspring rotor is movable and is keyed by
an engagement dowel that is molded onto the rotor
hub between two fins that are cast into the lower
surface of the steering wheel armature. A yellow rub-
ber boot is installed over the engagement dowel to
eliminate contact noise between the dowel and the
steering wheel. The two lobes on the turn signal can-
cel cam on the lower surface of the clockspring rotor
hub contact a turn signal cancel actuator of the
multi-function switch to provide automatic turn sig-
nal cancellation.
Two short, yellow-sleeved pigtail wires on the
upper surface of the clockspring rotor connect the
clockspring to the driver airbag, while a steering
wheel wire harness connects the two connector recep-
tacles on the upper surface of the clockspring rotor to
the horn switch feed pigtail wire connector and, if
the vehicle is so equipped, to the optional speed con-
trol and remote radio switches on the steering wheel.
Like the clockspring in a timepiece, the clockspring
tape has travel limits and can be damaged by being
wound too tightly during full stop-to-stop steering
wheel rotation. To prevent this from occurring, the
clockspring is centered when it is installed on the
steering column. Centering the clockspring indexes
the clockspring tape to the movable steering compo-
nents so that the tape can operate within its
designed travel limits. However, if the clockspring is
removed from the steering column or if the steering
shaft is disconnected from the steering gear, the
clockspring spool can change position relative to the
movable steering components. The clockspring must
be re-centered following completion of this service or
the tape may be damaged.
Service replacement clocksprings are shipped pre-
centered and with a plastic locking pin installed.
This locking pin should not be removed until the
clockspring has been installed on the steering col-
umn. If the locking pin is removed before the clock-
spring is installed on a steering column, the
clockspring centering procedure must be performed.
(Refer to 8 - ELECTRICAL/RESTRAINTS/CLOCK-
SPRING - STANDARD PROCEDURE - CLOCK-
SPRING CENTERING).
STANDARD PROCEDURE - CLOCKSPRING
CENTERING
The clockspring is designed to wind and unwind
when the steering wheel is rotated, but is only
designed to rotate the same number of turns (about
five complete rotations) as the steering wheel can be
turned from stop to stop. Centering the clockspring
indexes the clockspring tape to other steering compo-
nents so that it can operate within its designed
travel limits. The rotor of a centered clockspring can
be rotated two and one-half turns in either direction
Fig. 18 Turn Signal Cancel Cam
1 - LOCKING PIN
2 - CLOCKSPRING CASE
3 - CANCEL CAM
4 - LOWER CONNECTOR RECEPTACLE (2)
DRRESTRAINTS 8O - 19
CLOCKSPRING (Continued)

WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.
NOTE: Before starting this procedure, be certain
that the front wheels are still in the straight-ahead
position.
(1) While holding the centered clockspring rotor
and case stationary in relation to each other, care-
fully slide the clockspring down over the steering col-
umn upper shaft.
(2) Align and seat the hole in the locating tab at
the eleven o'clock position on the clockspring case
over the locating pin on the multi-function switch
mounting housing (Fig. 20).
(3) Install and tighten the two screws that secure
the clockspring to the multi-function switch mount-
ing housing. Tighten the screws to 2 N´m (20 in.
lbs.).
(4) Reconnect the two instrument panel wire har-
ness connectors for the clockspring to the two connec-
tor receptacles below the steering column on the back
of the clockspring housing.
(5) Position the lower shroud onto the steering col-
umn.
(6) From below the steering column, install and
tighten the one center screw that secures the lower
shroud to the steering column lock housing. Tighten
the screw to 2 N´m (20 in. lbs.).(7) Position the upper shroud onto the steering col-
umn. If the vehicle is equipped with an automatic
transmission, be certain to engage the gearshift lever
gap hider into the openings in the right side of the
upper and lower shrouds.
(8) Align the snap features on the upper shroud
with the receptacles on the lower shroud and apply
hand pressure to snap them together.
(9) From below the steering column, install and
tighten the two screws that secure the upper shroud
to the lower shroud. Tighten the screws to 2 N´m (20
in. lbs.).
(10) If the vehicle is equipped with the optional tilt
steering column, align the steering column tilt knob
with the tilt adjuster mechanism lever located on the
left side of the column just below the multi-function
switch control stalk and, using hand pressure, push
the knob firmly onto the lever.
(11) Reinstall the steering column opening cover
onto the instrument panel. (Refer to 23 - BODY/IN-
STRUMENT PANEL/STEERING COLUMN OPEN-
ING COVER - INSTALLATION).
(12) If a new clockspring has been installed,
remove the plastic locking pin that is securing the
clockspring rotor to the clockspring case to maintain
clockspring centering.
NOTE: When reinstalling the steering wheel, be cer-
tain to index the yellow rubber booted engagement
dowel on the upper surface of the clockspring rotor
between the two fins cast into the lower surface of
the steering wheel armature hub.
(13) Reinstall the steering wheel onto the steering
column. (Refer to 19 - STEERING/COLUMN/STEER-
ING WHEEL - INSTALLATION).
(14) Reconnect the steering wheel wire harness
connectors to the upper clockspring connector recep-
tacles. Be certain that the steering wheel wire har-
ness is routed between the steering wheel back trim
cover and the steering wheel armature.
(15) Reinstall the driver airbag onto the steering
wheel. (Refer to 8 - ELECTRICAL/RESTRAINTS/
DRIVER AIRBAG - INSTALLATION).
8O - 22 RESTRAINTSDR
CLOCKSPRING (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)

cal indexing to the defrost door, as it is electronically
calibrated by the heater-A/C control module. The
defrost door actuator cannot be adjusted or repaired
and, if damaged or faulty, it must be replaced.
OPERATION
The defrost door actuator is connected to the heat-
er-A/C control module through the vehicle electrical
system by a dedicated two-wire lead and connector
from the HVAC wire harness. The defrost door actua-
tor can move the defrost 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 defrost door will move in
one direction. When the module reverses the polarity
of the voltage to the motor, the defrost door moves in
the opposite direction. When the module makes the
voltage to both connections high or both connections
low, the defrost door stops and will not move. These
same motor connections also provide a feedback sig-
nal to the heater-A/C control module. This feedback
signal allows the module to monitor the operation
and relative positions of the defrost door actuator
and the defrost door. The heater-A/C control module
learns the defrost door stop positions during the cal-
ibration procedure and will store a Diagnostic Trou-
ble Code (DTC) for any problems it detects in the
defrost door actuator circuits. The defrost door actua-
tor can be diagnosed using a DRBIIItscan tool.
Refer to Body Diagnostic Procedures.
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 instrument panel from the vehicle
(Refer to 23 - BODY/INSTRUMENT PANEL/IN-
STRUMENT PANEL ASSEMBLY - REMOVAL).
(3) Disconnect the wire harness connector from the
defrost door actuator (Fig. 19).
(4) Remove the screws that secure the defrost door
actuator to the HVAC housing.(5) Remove the defrost door actuator from the
HVAC housing.
INSTALLATION
(1) Position the defrost door actuator into the
HVAC housing. If necessary, rotate the actuator
slightly to align the splines on the actuator output
sleeve with those on the defrost door linkage.
(2) Install and tighten the screws that secure the
defrost door actuator to the HVAC housing. Tighten
the screws to 2 N´m (17 in. lbs.).
(3) Connect the HVAC wire harness connector to
the defrost door actuator.
(4) Install the instrument panel (Refer to 23 -
BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL ASSEMBLY - INSTALLATION).
(5) Reconnect the battery negative cable.
Fig. 19 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
DRCONTROLS 24 - 21
DEFROST DOOR ACTUATOR (Continued)

(2) Assemble the HVAC housing (Refer to 24 -
HEATING & AIR CONDITIONING/DISTRIBUTION/
HVAC HOUSING - ASSEMBLY).
(3) Connect the HVAC wire harness connector to
the evaporator temperature sensor.
(4) Install the HVAC housing (Refer to 24 - HEAT-
ING & AIR CONDITIONING/DISTRIBUTION/HVAC
HOUSING - INSTALLATION).
(5) Reconnect the battery negative cable.
MODE DOOR ACTUATOR
DESCRIPTION
The mode door actuator is a reversible 12-volt
Direct Current (DC) servo motor. The mode door
actuator is located on the HVAC housing, behind the
instrument panel and is mechanically connected to
the mode door.
The mode door actuator is interchangeable with
the actuators for the blend door(s), defrost door and
the recirculation door. Each actuator is contained
within an identical black molded plastic housing with
an integral wire connector 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 linkage that drives the proper door.
The mode door actuator does not require mechanical
indexing to the mode door linkage, as it is electroni-
cally calibrated 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 A/C-
heater control through the vehicle electrical system
by a dedicated two-wire lead and connector from the
HVAC wire harness. The mode door actuator can
move the mode door in two directions. When the A/C-
heater control pulls the voltage on one side of the
motor connection high and the other connection low,
the mode door will move in one direction. When the
A/C-heater control reverses the polarity of the volt-
age to the motor, the mode door moves in the oppo-
site direction. When the A/C-heater control makes
the voltage to both connections high or both connec-
tions low, the mode door stops and will not move.
These same motor connections also provide a feed-
back signal to the A/C-heater control. This feedback
signal allows the A/C-heater control to monitor the
operation and relative position of the mode door
actuator and the mode door. The A/C-heater control
learns the mode door stop positions during the cali-
bration procedure and will store a diagnostic troublecode (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 Body Diagnostic Proce-
dures for more information. The mode door actuator
cannot be adjusted or repaired and, if damaged or
faulty, it 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.
(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
mode door actuator (Fig. 22).
(4) Remove the screws that secure the mode door
actuator to the HVAC housing.
(5) Remove the mode door actuator from the HVAC
housing.
INSTALLATION
(1) Position the mode door actuator onto the HVAC
housing. If necessary, rotate the actuator slightly to
align the splines on the actuator output sleeve with
those on the mode door linkage.
(2) Install and tighten the screws that secure the
mode door actuator to the HVAC housing. Tighten
the screws to 2 N´m (17 in. lbs.).
(3) Connect the HVAC wire harness connector to
the mode door actuator.
(4) Install the instrument panel (Refer to 23 -
BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL ASSEMBLY - INSTALLATION).
(5) Reconnect the battery negative cable.
DRCONTROLS 24 - 23
EVAPORATOR TEMPERATURE SENSOR (Continued)

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 HVAC housing, on the top of the
air inlet housing. The recirculation door actuator is
mechanically connected to the recirculation air door.
The recirculation door actuator is interchangeable
with the actuators for the blend door(s), defrost door
and the mode door. Each actuator is contained within
an identical black molded plastic housing with an
integral wire connector receptacle. Integral mounting
tabs allow the actuator to be secured with three
screws to air inlet housing. Each actuator also has an
identical output shaft with splines that connects it tothe linkage that drives the proper door. The recircu-
lation door actuator does not require mechanical
indexing to the recirculation door linkage, as it is
electronically calibrated by the heater-A/C control
module. The recirculation door actuator cannot be
adjusted or repaired and, if damaged 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 lead and con-
nector of the HVAC wire harness. The recirculation
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 Body Diagnostic
Procedures for more information. The recirculation
door actuator cannot be adjusted or repaired and, if
damaged or faulty, it 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.
(1) Disconnect and isolate the battery negative
cable.
Fig. 22 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 - 24 CONTROLSDR
MODE DOOR ACTUATOR (Continued)