You guys are better than I am. I have no idea about his problem.
There is no information about what the trailer is. What year it was made. What kind of AC it is. No information at all.
I even checked his profile, no info there either.
The old Armstrong AC's had wall mounted thermostats, right? My Trade Wind doesn't have the original AC (replaced with a Coleman before I got it), but there's still an orphaned thermostat on the wall next to the one for the heater. It could be one of those, we don't know.
We can keep guessing, but some more info from the original poster (OP) would really help with the answers. In lieu of knowledge, photos (in focus and large enough to see) would help.
We're really willing to help if we can.
On Edit: There were posts discussing the AC controls, built-in thermostats on most roof air units. Those posts were there when I composed the reference to "You guys" Now we're suddenly down to only two replies. Magic I guess.