[Carl_g]

Thanks for the reply. I'll search more for the ideas you posted as well....the blower motor sounds like a possible cause but the mode does still change occasionally, just not on demand.
I managed to locate an actuator and although it took way too long to access, I got a look at the part.
I didn't pull it but got the part number (OEM 52402588). I looked it up and some sites list is as an air door actuator and others list it as a blend door actuator, but I've read different meanings of both.

Can anyone tell me if this part, in non techy lingo, means "the thing that makes the air go to different places"?

Thanks for any help/responses!

 

[Carl_g]

I searched some more and came across this helpful post:
How to replace HVAC air door actuator

So I turned the vehicle on and cranked the temperature and then lowered it while looking straight at the actuator I found on the passenger side and saw that the circular piece was turning on the unit indicating it was the actuator changing the temp. So I poked around and found the actuator on the drivers side and tried to change modes and nothing happened.

I got the part number (gmc oem part 52402598) and searched the web and found that it is the mode actuator and so tomorrow I'm going to get a replacement part and try to install it tomorrow and I'll post the results tomorrow!

 

[Carl_g]

Thanks for the heads up Silvey. I had to move a plastic air duct (for air flow to the floor) and yes it's exactly where you indicated. I unfortunately went to the passenger side first and took off the plastic shield that covers the other actuator. No harm done though.
The actuator wasn't in stock. It'll be here by tomorrow so hopefully it arrives and I can get it replaced and update this thread.

 

[Carl_g]

So, just for anyone who might need some help with this.....
I updated the new actuator and it all works perfectly! The part was grossly overpriced at 192.00 but considering the dealer wanted 1500.00, I'm pretty ok with the cost. With winter coming quickly, it'll be great to have all modes working again. So here's what I did:

I disconnected the negative end of the battery. No idea if you have to or not but I did just to be safe.

When you look at the alignment notches (see picture), make sure the new one is at the same setting as the old one (mine were both at what I would say is the 90 degree setting). You'll see what I mean when you see the picture. Since the connection rod is kind of a rectangle in shape, they have to be set the same or screwing the new one back in will not work.

1. Confirm what actuator is bad. If the HVAC doesn't change modes, your air door actuator is bad. It is located on the driver side. There is a HVAC floor vent tube blocking your view to see up the dash. It thankfully can be split apart at a connection right in the middle of the tube. Separate it and look up and slightly to the center (towards the console), and you will see it mounted sideways.
If your temperature doesn't change, or blend properly, your blend door actuator is bad It is located on the passenger side, under the glove box. You will have to remove the 3 bolts holding a plastic cover hiding all the bits. 2 bolts are easy to find and remove. The last bolt is close to the console and is a huge pain in the ass to remove. Once it is removed, you will see the actuator there mounted flat. There are 2 small bolts on each one and they will have to be removed.

2. Remove the 2 bolts holding the actuator. Smaller the hands, the less painful it is. Be slow with it.

3. Gently remove the wiring harness that connects to the actuator. There is a pressure clip holding it in as well, so be very gentle when removing it!

4. Plug the wiring harness into the new actuator

5. Mount the new one on. Right now if you haven't read the first warning about the setting of the actuator, you'll be wondering why it doesn't fit right. Happened to me! lol

6. Secure the new actuator with the 2 small bolts that you hopefully haven't lost.

7. Test the new actuator by connecting the battery and turning the vehicle on. Apparently you should not touch it for a minute or 2 because of the computer in the truck doing a re learn. I followed that instruction just to be safe.

8. Put any covers or anything else back together and enjoy sticking it to the dealer that was gonna stick it to you.

Anyway, I have very little know-how to do this but with help on forums and you tube, and now hopefully this thread, you'll have success as well.

Cheers!

I can't seem to attach the picture of the actuator so a description will have to suffice. The small circle on the casing has a notch on it. Make sure the notch is in the same position as the old one before you mount the new one.

 

[Carl_g]

Well, as long as the actuator is the same set up on the 2010 (I imagine it is), then the instructions should help you out. There were a few pointers I got on youtube as well.
Hopefully you get it fixed.....just as an FYI, I did this in the beginning of October and my install is still going strong although the plastic actuator is pretty flimsy and I'm sure I'll be doing this again at some point. But at least I'm not being screwed by the dealer!

Good luck!