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Blend Door Actuator?

Tiny
SYSRQ4651
  • MEMBER
  • 2007 CHEVROLET TRAILBLAZER
  • 4.2L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 133,484 MILES
Recently my front vents stopped working on my vehicle. I've tried to re-calibrate by taking out the fuse, waiting a couple minutes, putting the fuse back in, turning the car to run, letting it go through its motions, but that didn't work. The air blows cold, but it is only coming out at the feet, side vents and defrost. How do I replace the vent actuators?
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Tuesday, August 6th, 2019 AT 1:54 PM

35 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,643 POSTS
Hello,

This is common when the mode blend door actuator goes out. Here is a guide to help walk you through the repairs with diagrams below to show you how on your car:

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

Check out the diagrams (below). Please let us know what happens.

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Wednesday, August 7th, 2019 AT 8:02 PM
Tiny
HEIDI ANNMARIE BIRCH WOODYARD
  • MEMBER
  • 5 POSTS
  • 2006 CHEVROLET TRAILBLAZER
  • 5.3L
  • V8
  • AWD
  • AUTOMATIC
  • 90,000 MILES
I received my new actuator and it is identical to the one I removed for my vehicle that is the EXT model. The problem I am having is the tab/shaft that is connected to the vent door does not line up with the position on the new actuator. Even when I manually turn the shaft it does not come close to the position I need it to be in to slide the actuator on.
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
HEIDI ANNMARIE BIRCH WOODYARD
  • MEMBER
  • 5 POSTS
I did some experimenting with my old actuator and removed the cover. I was then able to lift up the gear and turn it to the position I would need it in. Pushed the gear back into place and replaced the cover. So my question is can I do this with my new actuator with out causing any damage? My only concern is on one side of the gear are some metal contacts and Im not sure exactly how the actuator works, I know it opens/closes the vent/temp door but don't know where these metal contacts come in to play.
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
When an actuator is replaced you need to pull the fuse for that circuit in order for the actuator to reset. Not pull covers off to reset by hand. You can try what you are doing but not sure it will work.
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
HEIDI ANNMARIE BIRCH WOODYARD
  • MEMBER
  • 5 POSTS
I understand that. Maybe I was not clear in describing the problem or asking my question. I know it has to be re-calibrated after I get the part on. The problem is, the shaft has a tab and can only fit in the actuator if the tab lines up with the recessed part on the actuator. I can turn the shaft a little but its not enough to fit. I just want to get my car back together, not wait longer to return and reorder the same part, if I can get this one on. This was a brand new part so who is to say the next one is going to be in the position it needs to be in? Then I am waiting even longer.
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
The shaft may be stuck so try moving in other direction see if that helps at all then see if it will move to where you need it.
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,643 POSTS
Hello,

Is the actuator and OEM replacement? I have seen where aftermarket units have the wrong gear position.

Please let us know what you find.

Cheers, Ken
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
HEIDI ANNMARIE BIRCH WOODYARD
  • MEMBER
  • 5 POSTS
Yes, it is a replacement. And I did move the shaft back and forth, it moves freely and fully opens and closes the vent door but it is not enough to line up with gear on the new actuator. Since this part fits so many different vehicles I would think the gear could be moved if need be since it can only go on one way. Think I'm going to take a chance, open it up and move the gear. I haven't found any solutions except for returning it and ordering another.
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Ok may as well
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
JEREMY REESE
  • MEMBER
  • 1 POST
  • 2005 CHEVROLET TRAILBLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 160,000 MILES
How do you get to/replace the driver side temperature actuator? The A/C went out in all vents so I replaced the resistor and harness to the blower motor as they had burnt through the connectors. This fixed the A/C mostly. Although now the issue is the driver side vents will not cool down but the passenger and rear does become cold. Also, there is a lot less air flow from the drivers side vents. Finding the actuator there is this metal plate in front of it with bolts inside and outside of the plate. Is this the right actuator to fix both problems and how do I remove/get around this plate?
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,643 POSTS
Please let us know what happens.

Cheers, Ken
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning.

I attached a picture of the actuator and its location. The unfortunate problem is the dash has to be removed to gain access to the motor.

Roy

REMOVAL PROCEDURE
1. Remove the I/P carrier.

ImageZoom/Print

2. Remove the left side air temperature actuator (1) retaining screws.
3. Disconnect the left side air temperature actuator electrical connector.
4. Remove the left side air temperature actuator.

Dash removal procedures

emoval Procedure

1. Remove the center floor console.
2. Remove the instrument panel (IP).
3. Remove the steering column with the steering wheel attached.
4. Remove the floor console bracket.

ImageZoom/Print

5. Remove the splice pack from the floor panel located on the right side of the HVAC center support bracket (5).
6. Remove the HVAC center support bracket (5) from the HVAC module (2).

ImageZoom/Print

7. Remove the side window defogger duct.

ImageZoom/Print

8. Remove the instrument panel cluster (IPC) wire harness attachments (1) from the steering column support bracket and IP carrier.
9. Remove the speaker wire harness attachments from the steering column support bracket and IP carrier.

ImageZoom/Print

10. Remove the IP wiring harness retaining screws (1) from the IP support brackets, located near the steering column support bracket.

ImageZoom/Print

11. Remove the 2 bolts (1) located at the top of the steering column support bracket.

ImageZoom/Print

12. Remove the 2 bolts (1) located underneath the steering column support bracket.

ImageZoom/Print

13. Detach and remove the SIR harness from the IP carrier.
14. Disconnect the radio antenna cable located near the blower motor.
15. Detach and remove the IP wire harness from the right side of the IP carrier.
16. Remove the radio harness form the IP carrier.
17. Remove the temperature sensors from the ventilation ducts.
18. Remove the transfer case control module from the steering column support bracket.

ImageZoom/Print

19. Remove the upper and lower bolts retaining the IP carrier to the right cowl side carrier bracket.
20. Remove the center bolt (1) that retains the IP carrier to the right cowl side carrier bracket.

ImageZoom/Print

21. Remove the upper and lower bolts retaining the steering column support bracket to the left cowl side carrier bracket.
22. Remove the center bolt (1) that retains the steering column support bracket to the left cowl side carrier bracket.

ImageZoom/Print

23. Remove the 6 nuts that retain the HVAC module to the IP carrier.
24. Remove the IP carrier and steering column support bracket assembly from the vehicle and place on a clean prepared surface.
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
HEIDI ANNMARIE BIRCH WOODYARD
  • MEMBER
  • 5 POSTS
Update- It worked! I opened the case, pulled out the gear then placed the "empty" half of case over the shaft, lining it up with the 3 screw holes. Next I put the gear on the shaft and finally I put the other half of the case w/motor and remaining gears in place making sure the post inside that held the gears in place lined up with the "empty" half and pushed it together making sure all the outside tabs locked back into place. Put the 3 screws in, hooked up the connector and recalibrated the system. To my surprise everything now works as it should. I've let it run with both heat/ac (obviously not at the same time!) With different fan speeds and positions without any problems!
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,643 POSTS
Nice work, we are here to help, please use 2CarPros anytime.

Cheers, Ken
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
HALOFACTOR2580
  • MEMBER
  • 1 POST
  • 2004 CHEVROLET TRAILBLAZER
  • 4.2L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 179,031 MILES
My A/C blows cold through my driver side vents including the one in the dash. But my passenger side vents are blowing hot air. Could the blend door actuator be going out on the passenger side? And if so where is the location of the actuator on the passenger side?
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Welcome to 2CarPros.

If one side is working properly and the other isn't, chances are it is the actuator. Here are the directions for replacing the right side actuator. It is located under the dash and behind the glove box.

The attached pics correlate with the directions. I highlighted the actuator to help locate it.

Also, here is a link that shows in general how it is done. You may find it helpful.

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

2004 Chevy Truck TrailBlazer 2WD L6-4.2L VIN S
Air Temperature Actuator Replacement - Right
Vehicle Heating and Air Conditioning Air Door Actuator / Motor Service and Repair Procedures HVAC System - Automatic Air Temperature Actuator Replacement - Right
AIR TEMPERATURE ACTUATOR REPLACEMENT - RIGHT
AIR TEMPERATURE ACTUATOR REPLACEMENT - RIGHT

REMOVAL PROCEDURE
1. Remove the I/P carrier.

pic 1

2. Remove the air temperature actuator-right retaining screws.
3. Disconnect the air temperature actuator-right electrical connector.
4. Remove the air temperature actuator-right.

INSTALLATION PROCEDURE

pic 2

1. Install the air temperature actuator-right.
2. Tighten the air temperature actuator-right retaining screws.

NOTE: Refer to Fastener Notice in Service Precautions.
See: Heating and Air Conditioning > Vehicle Damage Warnings > Fastener Notice

Tighten
Tighten the screws to 1.9 N.m (17 lb ft).

3. Install the air temperature actuator-right electrical connector.
4. Install the I/P carrier.
5. Recalibrate the air temperature actuator on vehicles equipped with automatic climate control (C68), See: Vehicle > Programming and Relearning > Re-Calibrating Actuators

_________________________________

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

Take care,
Joe
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
PEGGY MARTIN-COOPER
  • MEMBER
  • 1 POST
  • 2003 CHEVROLET TRAILBLAZER
  • 4.2L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 180,000 MILES
Air only blows from defrost and floor. Which actuator controls this?
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
This is called the mode door actuator. I included the process on how to change this and how to calibrate it. Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed. Let me know if you have any questions. Thanks
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
LEVIGALOFF
  • MEMBER
  • 2 POSTS
  • 2003 CHEVROLET TRAILBLAZER
  • 4.2L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 206,000 MILES
I figured out my air actuator clicks now when I put the defrost on the foot only and the foot and defrost and even when I turn it off. Completely. But If I keep it on the front blowers or the front and foot blowers there’s no clicking sound. I can also change the temperature yet so I don’t think it’s the blend door actuator. Any idea on where the correct actuator would be to replace?
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Friday, February 12th, 2021 AT 10:19 AM (Merged)
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
If this is making the noise when defrost is on then it is most likely the defrost actuator. However, if there are settings that this happens on that defrost is not on then it is most likely the mode door actuator.

I am assuming you have a manual system based on how you were describing the issue. If you have an auto system just let me know and I can send you that info as well.

If it were me, I would just go ahead and put any actuator that you see when going in there. Just make sure you are using a good quality because I have put in many that were cheaper and took them out the next day because they were clicking.
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Friday, February 12th, 2021 AT 10:19 AM (Merged)

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