AC unit will not stay on. Any thoughts?

I agree with the others. It sounds like water flow. The south shore bays get a lot of eel grass during August, and it cloggs the strainers. But it could also be because of blocked air and icing.
1) check the strainer.
2) clean the filters on the front of the unit.
3) allow to defrost if iced up

If you need the number of a good a/c guy on the Island PM me. There's only one guy I use.

Agree, likely water flow. One pump probably feeds two ACs, and since both are acting up water flow seems like a likely place to start troubleshooting.

Yes, clean the strainer. Could be grass, mud, jelly fish, barnacles, all of the above... and one of our dock neighbors had an eel in his once.

May also have something like a plastic bag over the thru-hull outside the hull, and that might (or might not) respond to air pressure as from a shop-vac (on "blow").

Might also need to backflush the discharge outlets. Pressure water from your dock source will do it well enough.

And/or might have to clean the strainer twice; once to get the system running, once to flush out the rest of the muck that you might have just caused to travel through.

Yes, it's a good idea to clean inside air filters, yes good to clean the fins, all useful periodic maintenance... but I'm guessing those probably aren't the immediate cause here.

-Chris

Actually icing happens quite often to the boats around here if there's not proper ventilation (high humidity and cool nights, but again I think he'll find the problem when he opens his stainer. I think pump problems would have surfaced before now if it was an intallation problem.

Nick, for future reference you should check the strainers every day as part of your engine room check, especially in August around here because the eel grass breaks loose and cloggs everything; sea strainers, jetboat pumps, outboard props, etc. Normally you won't even have to open it. Just shine a light from the back of the glass and you'll know. Also look at how it's pissing out the side of your boat. When that slows down it's probably a clog.

Sure rub it in as we head into winter. It was 49* here the other night. My wife opened the window and I nearly froze. She was surprized when I was grumpy the next morning.

Mussels

Check the strainer, as others have suggested. Then remove the hose to the hull outlet and check it thoroughly.
Odds are, it's not weed or grass but healthy little mussels!
They get through the strainer as larvae and grow into mussels when the A/C is idle and get a grip on the hose. They make themselves a happy community.
Each few months toss a bromide tablet in the strainer, that should do it. Then again, it's a boat and I could be completely wrong!
Cheers.
Kafue

Thankfully mussles aren't a big problem on Long Island. They have great bay beaches and pilings to make their homes on, and outdrives of boats that don't move. Because the warm water season is so short mussles and barnacles attach mostly to things that won't move at all. Bromine is rarely needed here.If you've ever heard of South Bay strainers, they were invented here, because the eel grass in August/September is such a problem. It floats around the bays in large packs a few inches thick, and gets suck into intakes and wrapped around small hp props real bad. Alumunum props tend to make two seasons, with a sharpening in between.