Reposting this here in case you didn't see it. You also need to look for loose connections where your main wire is attached to the trailer. Loose connections can cause heat and fires.
It sounds like you are not hooked up to 30 amp service. If you are using an adapter to run from 20 amp service this can happen. If you are connected to the right service, it could be a bad plug or receptacle to the trailer or the one to the AC unit. Of course it could be something else, but this is where to start. An extension cord to the trailer that is not heavy enough or too long will do this too.
Dirt on the fins both inside and out will cause it to freeze up and not work right. as will a dirty filter.
More information will help.
1994 245 TD