[JRTJH]

There's "precious little information" in your post for anyone to offer any advice or guidance. Is your trailer still in the warranty? After that one year, some components are covered by a longer manufacturer's warranty. Some types of thermostats are covered longer than others. All of that said, if you're covered by the Keystone one year warranty, sometimes they will authorize an independent repair service and process the claim, or you can locate a repair center that is authorized by the thermostat manufacturer and he can file the claim for the thermostat warranty.

Where you fall into "peril" is if the problem is not with the thermostat, but possibly with the trailer wiring, air conditioner control box or furnace. In that case, you may be "on the hook for payment" for the repairs since it's not a "thermostat failure"....

So, depending on your warranty status, it may be covered, it may not. Something else to consider: If you've got to take time off from work, tow the trailer to the dealer, leave it, take more time off from work to go pick it up, tow it back home (or to storage), it may cost you more to have the dealer do the "warranty repair" than it would cost to just buy a replacement thermostat and "hang it on the wall" yourself..... Without knowing more about the specifics, it's a "wide open possibility" as to what might be the best, fastest or cheapest way to proceed.

ADDED: As for "thermostat reliability" they are "manmade components" and do fail, but for the most part, the digital thermostats seem to be very reliable and seldom have problems. Most of the problems tend to be loose wiring connections, owner induced failure or physical damage.