I did the blend door a couple months ago, I had no air instead of no heat. I was dreading it and put it off until it got to be 100 out here in Chicago, then I had to do it. I got the part from my local lincoln dealer for $43 and it took me about 4 hours in my garage to complete the job using the write-up pointed out in this thread. Don't worry about it, it's really not that bad, just follow the instructions to the T, don't try and take any shortcuts and be patient. Oh, and BE PATIENT oh and BE PATIENT!!!
Sorry, but I had to stress that part. Remember, these cars are aging and parts are hard to come by, if you get impatient and try and force something and it breaks, you are doing nothing but costing yourself more money and more headaches.
Good Luck....