Now that you have a symptom to go on, the experts will know what to do better than me.
If I were to guess, I would say your thermostat with a metal wire/probe that monitors the freezing of your evaporator IS doing it's job and shutting down your system like it should
WHY is this happening is the question?
* Sounds like the compressor is always running; and if refrigerant flows, then the system will keep cooling, which is good.
However, if you don't have enough volume of air passing over and threw those evaporator fins it will freeze, and that is what you are telling us.
==> All your binary switches are Normally Closed (NC) and open when there is a problem. So you are dealing with poor air flow or a bad TXV... IMO.
Here is what I found by googling: What causes the evaporator to freeze in an RV?
==> Do you have an air filter that is clogged? ...My coach did not come with one, but maybe your newer RV does?
* My guess is that you have a bad expansion valve (TXV), but before you open up your "closed AC system," you might look at these easy to troubleshoot items:
* Have you go a Bosch Relay mounted on your firewall above your generator? ...If so test it. I.e., pins 85-86 are the coil voltages and you should have "continuity" between them.
If you don't know how to test a relay then just buy a new one for $10-$15 at any auto parts store and see if that fixes your problem? If not, it's always good to have a spare relay.
* Maybe your temperature control board (behind your 3-knobs) is causing you trouble? (See picture below.) Are you getting full fan speed?
* If still no luck, turn up your air temperature so you blend door is not 100% recycling cool air.
Note: Most people have the opposite problem. I.e., they can't get there AC cold enough. So consider yourself lucky... that your thermostat is shutting down your compressor.
Question: When your evaporator was freezing over, was it humid outside?
* Final comment: If you do replace your TXV you should also replace your Receiver-Air-Dryer. These things are cheap and easy to replace; and you can use any type. Mine took an AC-Delco Receiver-Air-Dryer... and FYI Winnie installed a Ford/Sanden Compressor. So don't be surprised if you find second source parts from the automotive industry that predate your RV by more than 5 years! ...My Mercedes TXV was used back in 1998 and I drive a 2004 Itasca Horizon 40AD.
* Your 134A weight is also placard on the back of your firewall. However, you can add 10% more and this is a good idea IMO. However, some "stuffy" AC mechanics will not put in more that what is called for. So just tell them what you want and maybe they will not see the placard.