[Maxwell]

On mine you could either attach the drain hose to the front or the back of the drain pan on the AC unit... The installer (not Tiara) mistakenly attached to the front so when I would run the boat it would overflow instead of drain due to the attitude of the boat. We just moved the hose to the aft drain fitting and all good. This was obviously kind of a fluke... However drain pans can get clogged with debris etc which you can usually clean with a wire coat hanger etc. The pan may also not drain if the condensate hose has any low (uphill) points in it. Not sure where they ran it from the factory but you want to make sure that it didn't come loose anywhere as any slight sag in the hose will cause it to back up since its not pressurized.

Other things to check would be plumbing to the wet bar sink to starboard, or if you have an ice maker up there instead of a fridge.

Max