Been there done that - all of that. First it was leaking down a light fixture in the front so assumed it was the front AC. Mobile repair came out and tightened the screws/bolts on all three AC's. Be careful as those bolts are not meant to squash the gasket, just compress it a little.
Anyhow, after that fix and a few weeks later in another downpour it starts coming in from a different light fixture, now more towards the middle AC. Fortunately we didn't hit any more rain and we were on our way to Lippert and then Master Tech RV in Elkhart.
When the techician came down off the roof he said that as he was climbing and his head cleared the edge of the roof he could see a space under the seal of the 2nd AC. It was not drawn up. Apparently someone did some repairs to it, maybe even replaced it, or just time took its toll but there was a gap. He said he was going to replace the seal and draw up the roof to the gasket line with new bolts. I had them replace all 3 seals.
No more leaks - but hey, that was my problem. Could be any of the ones mentioned. Just remember that the bolts on the AC are not supposed to compress the gasket flat, just tight enough to make a seal.
Wayne MSGT USMC (Ret) & Earlene (CinCHouse)
2015 Winnebago Tour 42QD 2008 Winnebago Destination 39W
(RVM-14) It is what it is, and then it is what you make of it.