2017 Thor Compass a/c works on generator but not 30 amp

X2 on making sure other electrical is off, such as electric water heating. I had a mystery draw that turned out to be a water hot pot that had been accidentally switched on!

30 amp circuit should run that just fine. I actually run my A/C off a 15amp circuit no problem. If 30 won't start it, you should monitor voltage in the coach when it tries to start, and see if its dropping below 110 volts during startup.