Now that's where I'm at. If you have been removing and installing the beauty cover, I'm thinking you have broke and or pinched a line. One coming loose inside the fender would only be on a rare occasion. Not really inside the fender but it's behind it. Now that you see just how little that line is, carefully trace it. This could also be the blend door actuator being stuck, since it did just sit for 4 years. Like I said before, make the fender removal the very last option because I have only heard of them coming loose in there maybe twice. I also wanna say that these people had removed hoods and fenders and one was pinched and the other needed the whole assembly that sets up there on the top of the fender well. If you haven't been taking off the fenders, it's unlikely that it would be in there so don't worry. Hopefully it's as simple as GMAN's line break.
On a side note, if you're the only one looking under the hood, I would just leave the beauty cover off. I know it hides a lot but it tends to get in the way more than looking pretty. The more heat it had to endure, the more brittle it's going to get and if you ever sell the car, you would want that part in the best condition as possible. I keep mine right above the garage in the attic because nobody but me ever looks under the hood. Let that ole 4.6 breathe.