New AC?

[oceanicdb]

Original Dometic AC went out in my 93 Sovereign 21. AC was freezing up, discharging water inside onto floor non stop once it's cold. I was told by local RV repair center that they are "sealed" units with the only option being 100% replacement with new unit. Is that correct or is there a second option?
If it does need replacement, any information with regards to model that will replace this unit, best place to purchase and ballpark cost to get the unit properly installed is appreciated.