AC Pump becomes airbound

[boat-bidder]

I have an AC pump that has worked flawlessly supplying cool water to 3 24k btu Dometic AC heat exchangers since 2010. Last summer the pump started to get airbound, shutting down the AC with the HPF fault. I bleed the air and everything works fine again…for a while. At the same time a sump box for the condensation from these chillers has been filling with water and pumps out every 30mins or so. Prior to the air problem, this box was always dry.
Finally the first of these 24k units has failed and I am told by one AC expert that the failure is unrelated. I don’t buy that, it’s too coincidental.
Anyone have a thought on why the system is getting airbound? Where the water in the sump box is coming from? And, is it possible to repair the heat exchanger which uses R-417a refrigerant?