AC kicking breaker

Ok, I've searched the forum and tried some of the tips I have found but nothing has helped. We have a 2012 Jayco Eagle 31.5RLTS with a 15K Coleman AC unit. The AC has not been used much over the 5 years we have had the trailer but it has always worked when needed until last week. We were hooked up to 30 amp service at a park and the AC would kick the breaker in the trailer after 30 to 90 seconds. I tried the service at the next site over and same thing. Now that we are home I have been trying to find the problem. At home it has tripped the 20 amp breaker at the pannel in the barn. Then tried my 2 Honda 2K Generators and this time it caused the generators to fault and cut power to the trailer. I have not had it trip the breaker in the trailer since we have been home though.

I opened the unit on the roof and the fan spins free and the condenser is clean.The squirrel cage fan inside spins free and the filter is clean. Changed the breaker and no help. I checked the wiring in the basement and no damage there and all the connections are clean and tight.

What's next? Anyone able to tell me where else I can look?

Thanks
Steve