So, I made this repair yesterday. It wasn't fun, at all. It took me about 5 hours soup to nuts. I used the link below as a guide to do the repair. Thanks to 737mechanic for the video! If you're going to do this repair yourself, I suggest you watch this video.
A few things to be prepared for.
Remove the front seat:[/U][/B] This takes about 5-10 minutes, definitely worth the time. Lay something down to pad your back, trust me on this.
Remove the air duct: This can be done before or after the BCM (Body Control Module), it's easier to do with the BCM removed, you have to disconnect the BCM harnesses, drop the BCM, then remove the duct.
Remove the BCM: I removed the duct first, it was a little bit of a fight, but it came out. The removal of the BCM isn't rocket science, but becareful of the release clips on each of the harnesses, broke one with just my finger nail.
Remove the blend door actuator: This is just two small screws, takes a minute.
Cut your opening: 737mechanic used a "Hot Knife", an improvised exacto knife blade to a small single probe soldering iron. I used a double probe soldering iron with a tip a ground down to a knife like sharpness. This is definitely the way to go. It was fast, controllable and accurate. The biggest advantage to it was you don't need to worry about hitting the coil/core just behind the access point, unless you jam the hot knife through, your're not going to damage to coil/core. This life less than an eight of an inch space to fill in.
Remove the newly cut piece: This will take a little finesse. The hot knife works great, but there was a couple of spots where the molten plastic, re-adhered to itself. It will come out, but be careful not to break it! Clean up the edge of the cut, if you use a hot knife, on both the removed piece and the vehicle.
Install the new blend door: I bought a new door from RoackAuto. It was under $20 for the door and delivery. If you set the new blend door and the white actuator adapter piece in just right, it'll allow you to carefully install the removed piece and catch that end, for the reinstall.
Install the removed piece: This is where I had a shit ton of problems! I couldn't get the piece to sit back in either with or without the new blend door. After a bit of really looking at the piece, on my 2015 anyway, there's two locations within the mold of the removed piece (inner ans outer), that need to join to get it back in. The two locations are a channel design. I couldn't get it. So being an HVAC guy, I determined I could remove the inner channel, without it losing any function of the repair. I took an exacto knife and carefully cut the inner channel off completely. The piece went right in and fit great after doing this. I was able to set the new door as stated above and install the removed piece.
Seal the repair: I used black silicone sealant to do this. I figured if it breaks again, I can just cut the silicone out, remove the old door and so on. I sealed around the entire removed piece, not just where I cut, just to be sure.
Set the actuator: This was a little bit of a PITA. I temporarily re-installed the BCM harnesses to do this. With the blend door actuator harness reinstalled, take note of the rotation of the shaft in relationship to the position of the blend door. If I remember, when the temp dial is turned to heat, the blend door should be in the down position. Remove the harnesses from the BCM.
Install the blend door actuator: Install actuator on the alignment post and reinstall the two screws and harness.
Reinstall the BCM and air duct: This was another difficult step for me, until I figured out a way to do it in the right order. If you fully install the BCM, the duct is next to impossible to reinstall without breaking something You'll notice when you remove the plastic BCM module from the metal mounting plate that the module itself is within a plastic framework. Remove the BCM from this frame and just reinstall the frame on the metal bracket first. Next, install the air duct with the hex head screw loosely installed. This will aloow you to install the BCM and harnesses with wiggle room. Slide the BCM up from the bottom until it clicks into place, into the plastic frame that was installed to the metal bracket. Next install all of the BCM harnesses. Tighten up the hex head screw and install the torx screw.
If you happen to check the operation of the repair before you reinstall the drivers seat, you'll get a "Service Airbag" notification on the DIC. It's because the drivers seat airbag can't be found by the system. This goes away after the seat is reinstalled.
I hope these tips help someone to make the repair a little easier. If anyone has any questions, feel free tom ask. I didn't take any pics or video as there's enough out there. I thought I'd just give my experience to help others.
By the way, the repair works awesome!