Does it overload IMMED on start up or does it take a minute or 3?
If the latter: How long since you cleaned the condenser coils?
I have had 4 A/Cs on my RV 2 Carriers, now deceased, an Advent Air (Dometic knockoff I'm told) and now a Carrier.. all but the Coleman (and that's just luck) have tripped their 20 amp branch breakers when the condenser clogged. The only reaosn and I mean the ONLY reason the Coleman has not is the Advent beat i to it and when I went up to clean it I thought.. "While I'm up here might as well check" and sure enough,, it was clogged with Cottonwood "Cotten" too.
But if it's overloading on startup.. See the above responses.