[SteveC7010]

If the unit is freezing up inside the trailer. there are a number of possible causes:

Bent fins will block air flow. Lower air flow and the condensate builds up rather than dropping to the drainage area. Then the freezing starts.

Dirty filter blocks air flow. You said it was clean, but still going to list it.

Dirt in the fins also blocks air flow. I usually clean mine with careful application of blasts of compressed air through a nozzle.

Air has no place to go. This is usually a blocked duct.

The outside of the A/C needs to be clean too. Remove the cover and clean/straighten the fins. When you remove the cover, be careful. There may be a wasp nest or similar in there.

The condensate normally produced by the A/C is drained to the outside of the unit and then runs across the roof to a gutter. You'll want to locate that path and make sure it's clean.

As the previous poster pointed out, these RV A/C units are pretty robust. It they are malfunctioning as you describe, it is a certainty that something is blocked somewhere.