Our Revolution had o rings in line replaced and filled with refrigerant several times. Finally it wasn't putting out any cool air in Kingman,AZ last year, again. The evaporator under the coach, is part of the chassis, was corroded etc. Found the only one available, or in existence apparently in Main, I think, and may have replaced the fan too. Freedom Roads in the Northeast was first Dealer, and it was apparently exposed to salt etc. I did get underneath and rinse it really good a few times, over, the 19 years we owned it.
Freightliner Service Center in Kingman got it fixed proper. Long hoses from the ac compressor forward.
Generally if they leak you will may see compressor lube and or dye leaking from the o-rings or holes or stains.
Once we got 100 miles east of Kingman we cut the generator and heat pumps off, Seldom had to use them the rest of way home. It blew cold. We many/most of the times kept the a/c set on max to recirculate inside air as there is no filters on the dash air intake, something I never got around to deigning and making. On a long trip with outside dash air everything seemed to get coated with dust.