Under sink vents

[OKI Marine]

Here at the beach and it is hot and humid at times. This morning I had noticed a little water on the shelf under one of the bathroom sinks. My initial thought was the drain was leaking and may need recaulked. I looked up under and noticed that there was condensation all over the under side of the sink bowl. There is a significant temperature difference between under the sink and the air conditioning running in that area. No water coming from supply lines. There is a vent inline on drain lines under the sink (not vented outside). Do these go bad? I wiped down everything with a towel and stuck a small dehumidifier under the sink on the shelf. I just checked it and it is collecting water and all is dry. Never had this happen before and we come to this beach nearly every summer. Any thoughts or comments about the under sink vent?

[Bama Rambler]

Those auto vents (air admittance valve) do fail from time to time, but it's not extremely common. Usually the first sign that it's failed is the odor you get. Rarely does it actually leak water out. Sometimes it will stick closed and then the sink will gurgle when trying to drain.

FYI, It's also common for the black tank flush, backflow preventer, to be installed in the cabinet with the sink.

[OKI Marine]

Thanks for the info