High humidity inside cabin - 330 Searay

I replaced my HVAC system 4 years ago due to a lightning strike. Replaced with same but new unit. This past year I keep cleaning mildew inside the cabin. Today inside the cabin in the morning, there was much moisture on the ceiling, dripping wet. The humidifier system appears to be working or at least it cycles twice a day as spec'ed. This has never been a problem before. Suggestions as to what is causing this?

The HVAC is a Dometic unit. I question if the programing is correct or the unit is faulty. I will run the test program to test the functionality of each featue.

Is the condensate drain plumbed overboard?... or does it dump to the bilge.
Also... In order for an A/C to lower the humidity, it has to run long enough. If the A/C comes on and then shuts off quickly (short cycles) because the temp has dropped enough, then you will not remove moisture from the air. This can be caused by two things... the A/C unit is too big (too high a BTU rating)... or the temp sensor is too close to the outlet of the A/C, i.e., the temp sensor get cooled off before the cabin does. Since the temp sensor usually located on the inlet of the A/C, it could mean that the outlet of the A/C is aimed too close to the inlet.

And, lastly, the temp setting of the A/C needs to be set below the local dew point temp.

Also... you said "humidifier system" did you really mean this or did you mean "dehumidifier". "humidifier" systems usually only operate on the heating cycle of a hot air heating system, i.e., an A/C system on reverse cycle.

Are you heating the cabin?
Sometimes heating a cabin (and the air within) causes more condensation issues than if no heat is used!

I store my SND F/B boat with no heat (wet West of the Cascades environment), and have almost zero issues!



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I found the port lights leaking. Had to remove and rebed. No more leaks. Lots of silicon on hulk to clean up.

Thanks for posting resolution. It's appreciated.