I just replaced three of the four actuators for HVAC mode blend actuator. I replaced left side (driver) Dorman 604-111, right side (passenger) Dorman 604-106. these two control the flaps for air distribution. Also, Doorman 604-115 Main this is the bugger up under the dash on drivers side that is hard to get to, hard to remove and the idiot that does all the clicking cause it has gummed up its gears. There is a fourth actuator just above this one that controls the fresh air, which I did not replace cause it was working fine. I could not have completed this job without this website which is my reason for writing cause there is a lot of fear and misunderstanding of terms being used. Basically, all the same and I wont go into process cause the ones on the first page pretty much nailed it!, except: I removed the dash completely, this I strongly advise as it takes just a bit over two hours and everything is plug and play.
I took pictures of each step of connections in the event my 66 year old brain forgot. You can get really good insights on process just like you did here by typing in the question. I also found a different thread where to remove the actuator you needed a $160 puller. that's B.S., go to home depot and purchase an anchor shackle 5/8 and go to their specialty drawers and get a socket type 8mm bolt 1.25X30 screw to replace the one in the shackle this has an allen wrench head which makes it easier to turn. Once you see the shackle you will realize it has to be spread apart to fit over the actuator and you have to cut off half the non-threaded part so that it will fit up against the cam on the inside.
Once you have it positioned just turn the bolt much like a gear puller and the sucker pops right off. This was easy for the left and right but the main actuator has no room which is reason for removing the dash, so much easier. This is like how you have to remove link in a chain nowadays since we do not have master links any more.
Now, how to turn the new actuator so that the line match up to old one. get a large beveled screwdriver and insert it in the cam so that it is wedged, use slight but constant turning pressure clockwise and slow, you should now hear the gears turning, go slow as you do not want to go past the mark. Install the actuator using old screws and 7/32 socket where you can get it to fit. On the main actuator this was difficult as there is just not enough room for the socket wrench. Get yourself a 7/32 open end wrench or 5.5 mm and good luck with that. I used pointed nose pliers as I used a tank of gas trying to find one. Again, follow directions on pulling the fuse, yep you have to go to the book that came with the car to find location.
Once all is installed, I connected the temp control module back up, replaced the fuse, reconnected the electrical to the shift lever, if you don't you will not be able to turn car off. I then turned the ignition switch to on so that the temp control module came on and ran thru all modes for air, heat, and air conditioning to insure all was well before I put it all back together.
I am retired and have three vehicles so pressure of completing the job to go to work was not an issue. just think, all this fun cause we had to replace our battery. Hope this helps as this site was best I found for us who believe the GMC dealerships are worse than our politicians.
Here's my bench a few weeks ago....
