I have a 1978 Class C Jayco RV (Dodge Sportsman). I have had the AC running before on a standard extension cord with no problems. I had it plugged in recently, and the AC worked for a while, and then the breaker tripped, and I could not reset it until later that day, presumably after it cooled down. Now, the breaker is reset, and everything else turns on in the camper but the AC. Does the roof unit have its own internal breaker? Is it going to be a hot rest of the summer?
Typical roof AC units will draw more current as they age and the compressor motor, fan motor wear out. And, as they age the initial Surge current increases which then kicks the breakers.
As to your question, normally there is no internal fuse or breaker. From your symptoms of an overheated breaker, and considering the age of your RV's AC, I would first change the breaker out, being the cheapest option, and if this didn't fix the problem, I would consider having a tech check out the AC for a bad compressor.
Updated on June 7, 2018
By Don Bobbitt