Dodge Ram Truck 1500-2500-3500. Manual — part 2051

SINGLE ZONE/DUAL ZONE DRIVER SIDE

1. Install the blend door actuator (1) onto the back of

the HVAC housing (2). If necessary, rotate the
actuator slightly to align the splines on the actuator
output shaft (3) with those on the blend door lever
(4).

2. Install the screws (1) that secure the blend door

actuator (2) to the HVAC housing (3). Tighten the
screws to 2.2 N·m (20 in. lbs.).

3. Connect the HVAC wire harness connector (4) to

the blend door actuator.

4. Install the instrument panel (Refer to 23 - BODY/

INSTRUMENT

PANEL/INSTRUMENT

PANEL

ASSEMBLY - INSTALLATION).

5. Reconnect the negative battery cable.

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DUAL ZONE PASSENGER SIDE

1. Install the blend door actuator and bracket assem-

bly (2) onto the top of the HVAC housing (3).

2. Install the screws (1) that secure the blend door

actuator and bracket assembly to the HVAC hous-
ing. Tighten the screws to 2.2 N·m (20 in. lbs.).

3. Connect the HVAC wire harness connector (4) to

the blend door actuator.

NOTE: Align the guide pin on the blend door lever
with the guides on the blend door linkage during
installation of the blend door lever.

4. Install the blend door lever (1) onto the blend door

actuator output shaft (2) and the blend door linkage
(3).

5. Install the instrument panel (Refer to 23 - BODY/

INSTRUMENT

PANEL/INSTRUMENT

PANEL

ASSEMBLY - INSTALLATION).

6. Reconnect the negative battery cable.

DR/DH

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ACTUATOR-MODE DOOR

DESCRIPTION

The mode door actuators are reversible, 12-volt direct
current (DC) servo motors. The heating-A/C systems
on this vehicle use two mode door actuators. One for
the panel/floor-air door and one for the defrost-air
door.

Both the panel/floor door actuator (1) and the defrost
door actuator (2) are located on the driver side end of
the HVAC housing (3), close to the dash panel.

All actuators (1) are interchangeable with each other.
Each actuator is contained within an identical black
molded plastic housing with an integral wire connector
receptacle (2). Each actuator also has an identical
output shaft with splines (3) that connects it to its
respective door linkage and three integral mounting
tabs (4) that allow the actuator to be secured to the
HVAC housing. The mode door actuators do not
require mechanical indexing to the mode-air doors, as
they are electronically calibrated by the A/C-heater
control.

OPERATION

The mode door actuators are connected to the A/C-heater control through the vehicle electrical system by dedicated
two-wire leads and connectors of the HVAC wire harness. The mode door actuators can move the defrost-air door
and the panel/floor-air 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-air door will move in one direction. When the A/C-heater
control reverses the polarity of the voltage to the motor, the mode-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 mode-air door
stops and will not move. The A/C-heater control uses a pulse-count positioning system to monitor the operation and
relative position of the mode door actuators and the mode-air doors. The A/C-heater control learns the mode-air
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.

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The mode door actuators are diagnosed using using a DRBIII

T

scan tool (Refer to 24 - HEATING & AIR CONDI-

TIONING - DIAGNOSIS AND TESTING and to 24 - HVAC Electrical Diagnostics for more information).

The mode door actuators cannot be adjusted or repaired and, if faulty or damaged, they must be replaced.

REMOVAL

WARNING: On vehicles equipped with airbags, disable the airbag system before attempting any steering
wheel, steering column, or instrument panel component diagnosis or service. Disconnect and isolate the
battery negative (ground) cable, then wait two minutes for the airbag system capacitor to discharge before
performing further diagnosis or service. This is the only sure way to disable the airbag system. Failure to
take the proper precautions could result in an accidental airbag deployment and possible personal injury or
death.

NOTE: The heating-A/C system is equipped with two mode door actuators, one for the panel/floor-air door
and one for the defrost-air door.

PANEL/FLOOR DOOR ACTUATOR

1. Disconnect and isolate the negative battery cable.

2. Remove the instrument panel from the vehicle

(Refer to 23 - BODY/INSTRUMENT PANEL/IN-
STRUMENT PANEL ASSEMBLY - REMOVAL).

3. Remove the screws (1) that secure the panel/floor

door actuator (2) to the back of the HVAC housing
(3).

4. Remove the panel/floor door actuator from the

HVAC housing and disconnect the HVAC wire har-
ness connector (4) from the actuator.

5. Remove the panel/floor door actuator from the

vehicle.

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