2005, 2500 Diesel Ac Blend Door?

[Nitsud84]

So I have purchased a blend door for my ac issue which may be more than one problem. I have a dual electronic controlled ac. For a period of a month it was going crazy, no matter where I told the air to go it did it did what it wanted. At first it started by just running through all the zones randomly then sometimes ending back where it started. But now it has stopped randomly going through the zones and is stuck on defrost, and I can't get it to blow anywhere else. I took it to the garage and they told me a blend door needed replacing. After seeing the price tag, I thought I could do it myself. After semi taking the dash apart I determined that almost if not the entire dash will need to come out. So I am hoping someoneknows if A, I am replacing the right part that I have been told would fix it, and B is there a manual or a simpler way to get to this thing. Any thing will help, thanks.