While on the way to NAC for GV reunion, we stopped at Cracker Barrel for the night. Everything seemed fine, AC was working, almost too good, then the thunk of the ATS would shut everything down for 5 seconds and it would thunk again and everything would come back on, but then it continually cycled on and off unless I shut off the the AC's. At the time we were only running one rooftop. Fan only was fine, but switch to cool and it would kick off approximately every 2.5 minutes. It always come back on. I watched the generator, it never stopped, but did seem to shudder. It was one in the morning so I didn't do a lot of troubleshooting, plus I don't know a lot about generators and ATS, but I'm trying to learn and the GV is giving me a lot of OJT. I changed the oil, oil filter and air filter before we left. I tested running both AC's on the generator before we left the house and they ran fine, although I didn't run them for very long. On shore power they seem to work fine and we had over an hour in the parking lot with cool air, but then it went south and would kick out the generator, or the ATS. No better this morning, we're in a campground tonight so hopefully things will work plugged in. Sorry for the long post, I just wanted to give as much info as possible.
Here is where I would start:
With generator off, shore power disconnected, remove the lid to the ATS.
Check for burned wires, loose connections.