your symptom is a common 'loose' wire at the breaker issue - when not on shore or generator, tighten it and it will probably solve that problem.
or, the weaker could be 'weak'...replacing it with another one might prove this, if the a/c then continues working without tripping. If so, then replace it with a new one and you should be good.
Even shore power breakers can be weak, especially overused 30amp ones at rv parks and campgrounds - they trip too quickly.
I don't know of any 'filter' for roof air conditioners other than the one in the a/c unit's cover itself... if one's not there, then you can add one... it's just simple filter material you can buy at w*mt or hardware stores.
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