Only thermocouple I know of is used to tell the AC room temp.
However a coil should never freeze even if run continuously forever. It's most likely either not getting enough air flow through it, or is low on refrigerant. Be sure the filters are not clogged and it has good airflow first, that is usually the problem.
I had a similar problem that I fixed by installing a 6K in the Stateroom, an advantage of a separate small AC is it will run off of a Honda
, or the inverter
if the engine