HVAC Blend door actuator malfunction

[sweettsinger]

Good morning Y'all! I have a 2006 Trailblazer LS W/L6.
I posted a question a few months ago about the problem I was having with the HVAC air flow direction and received some great advice! I replaced the actuator & for extra measure the control module and it fixed the problem. Well, it's back with a twist!
I purchased another actuator ( Dorman this time) however it didn't fix it!
The problem is that when the key is in the on position it works fine however when the engine is running the gears only go in one direction ( my mechanic opened the actuator and watched the function ). We put in the other actuator and it does the same thing. Thinking it must be the control module we put in my old one (OE) with the same result. We've also checked all the fuses.
Any help would be appreciated!

 

[Mooseman]

Try resetting the system by pulling the HVAC-B fuse under the seat for about 30 seconds, put it back in, turn the key to RUN (but don't start it) and let it do the relearn. Don't touch the controls until you hear everything stop moving.

 

[sweettsinger]

I am having an issue calibrating the front actuator after changing the battery. For some reason it is not reacting, I get no sound when I reset it. I have bought a new actuator 3 times now so I don't know the original position it was in. By the way I have a manual system. I also replaced the control module. I hope I've explained it well enough! If not, let me know!

 

[Mooseman]

Have you tried the reset procedure above?

 

[sweettsinger]

Yes! Multiple times! Here's an update!
Good evening y'all! I have a '06 TB LS w/4.2, manual control a/c.
I have been having this issue for several months now!
The actuator isn't directing the blend doors to lock in after calibration. I finally found a mechanic with the right scanner to diagnose the problem.
The code that came up is 3761 Defrost A/C flow control 3. In the history it showed code B3770 ( air flow control module actuator ) I'm gong to order another actuator for the defrost.
I have 2 questions. One: is there something else that could be causing the problem? Second question: Is the defrost actuator the same part # as the blend door actuator? When we pulled both and compared them they look exactly the same!
Thanks in advance for any advice!