I have a 1990 model with the original AC unit, which works great - so far. It's an old DuoTherm that will turn the RV into a freezer even on a hot day. If, I was going to spend a dime up there I would replace the whole unit. We take dogs to the beach with us. We go do stuff during the day and I always stress a little over that old AC unit. With that said, we had a three year old Carrier 15,000 BTU unit on the van and it quit with no warning. Of course, it was a Carrier, the worst roof units ever made in the history of planet earth.