Mode actuator? My vents will not change from floor, vent or defrost?

This is due to the mode door motor/actuator. I attached the process on how to replace it. Let me know what questions you have. Thanks

I am sure you have electrical actuators and not cable connected so we need to remove the actuator and keep it connected to the connector and then try to change the position. We need to see if the actuator will move or not. If it moves then the door is stuck. If not, we need to start checking voltage. Let us know what you find and then we can go from there. Thanks

Hi,

If you are unable to control the air flow direction, chances are there is an issue with what is called a mode door actuator. This actuator is responsible for directing air flow to the requested location.

If you look at pic 1, it shows the location of the mode door. What I would like you to do is remove the actuator and check to see if it moves when you change air flow directions. Also, make sure nothing is disconnected or damaged.

To access and remove the actuator isn't too hard, but will take more than a minute. Here are the directions for replacing the actuator. Before replacing it, check to make sure it isn't working and make sure nothing is disconnected or damaged. The attached pics correlate with the directions.

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1999 Chevy Truck C 1500 Truck 2WD V8-4.8L VIN V
Mode Actuator Replacement
Vehicle Heating and Air Conditioning Air Door Actuator / Motor Service and Repair Procedures Heating and Ventilation Mode Actuator Replacement
MODE ACTUATOR REPLACEMENT
REMOVAL PROCEDURE

pic 2

1. Remove the floor air outlet duct extension (1) from the floor duct (2).

Pic 3

2. Disconnect the electrical connection at the mode actuator (10).

Pic 4

3. Remove the mode actuator mounting screws from the HVAC module.
4. Remove the mode actuator as an assembly with the actuator cam.

INSTALLATION PROCEDURE

pic 5

1. Install the mode actuator as an assembly with the actuator cam.
- Line up the heater/defroster valve lever with the mode actuator cam slot.
- Line up the A/C valve lever with the mode actuator cam.

NOTE: Refer to Fastener Notice in Cautions and Notices.

2. Install the mode actuator mounting screw to the HVAC module.

Tighten
Tighten the mode actuator mounting screw to 1.6 N.M (14 lb in).

Pic 6

3. Connect the electrical connection at the mode actuator (10).

Pic 7

4. Install the floor air outlet duct extension (1) to the floor air duct (2).

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Let me know what you find or if you have other questions.

Take care,
Joe

Hi:

It sounds like the mode door actuator isn't working. That is what changes air flow direction. Here are the directions specific to your vehicle for replacing the mode door actuator. The attached pictures correlate with the directions.

1. Remove the floor air outlet duct extension (1) from the floor duct (2).
2. Disconnect the electrical connection at the mode actuator (10).
3. Remove the mode actuator mounting screws from the HVAC module.
4. Remove the mode actuator as an assembly with the actuator cam.

INSTALLATION PROCEDURE
1. Install the mode actuator as an assembly with the actuator cam.
- Line up the heater/defroster valve lever with the mode actuator cam slot.
- Line up the A/C valve lever with the mode actuator cam.

NOTE: Refer to Fastener Notice in Cautions and Notices.

2. Install the mode actuator mounting screw to the HVAC module.

Tighten
Tighten the mode actuator mounting screw to 1.6 N.M (14 lb in).
3. Connect the electrical connection at the mode actuator (10).
4. Install the floor air outlet duct extension (1) to the floor air duct (2).

Check out the diagrams (Below). Let us know what happens and please upload pictures or videos of the problem.

Hello,

This is common when the mode actuator goes out. here is a guide to help you change the unit out with diagrams below to help you with your truck:

https://www.2carpros.com/articles/replace-blend-door-motor

Check out the diagrams (below). Please let us know if you need anything else to get the problem fixed.

Hi,

The air flow direction on this vehicle is controlled by a mode door. Based on your selection, the mode door actuator changes the direction of air flow. What I would suggest is to remove the actuator and check it for operation. Chances are the actuator itself has failed.

Here are the directions for removal and replacement. The two attached pictures correlate with the directions.

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1996 Chevy Truck K 2500 Truck 4WD V8-305 5.0L VIN M SFI
Actuator Removal and Installation
Vehicle Heating and Air Conditioning Air Door Actuator / Motor Service and Repair Procedures Actuator Removal and Installation
ACTUATOR REMOVAL AND INSTALLATION
Mode Actuator Location

Pic 1

Mode Actuator Replacement

Pic 2

Remove or Disconnect
1. Negative battery cable.
2. Electrical connector.
3. Screws.
4. Adjuster links from control lever.
5. Mode actuator.

Adjust
A. Electrical connector to the actuator.
B. Turn the ignition key to the run position and let the actuator position itself.
C. Turn off the ignition key.
D. Remove the actuator from the electrical connection.

Install or Connect
1. Mode actuator.
2. Screws.
3. Adjuster links to control lever.
4. Electrical connector.
5. Negative battery cable.

Check circuit operation.

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I don't know if you will find this helpful, but here is a link that shows how a blend door actuator is replaced. The process is very similar. The difference is the link discusses a different actuator in the HVAC system that is responsible for temperature and not air flow direction. However, they are appear and work very similarly.

https://www.2carpros.com/articles/replace-blend-door-motor

Let me know if this helps or if you have other questions.

Take care,
Joe

No start position when reassembling cams. Cams must be in the start position, when attaching new actuator.