1. That tstat is NOT a Dometic wall tstat. That is an aftermarket tstat.
2. You need to contac the Easy touch people for help. The freeze thermister WILL READ the evap and it will get below 60 degrees.
3. The AC only holds about 1 lb of coolant. So, if a leak, it will leak enough to NOT freeze or even cool.
4. Remove the sensor from the evap. Unplug one wire from the control board. IF the compressor comes ON, leave it that way. If not, jump the 2 wires together and leave and observe operation.
5. Have you actually seen the coils covered in ICE? Doug
PS, SWAP the wall stats and see if the problem follows.
Do BOTH AC units do this?