OK disclaimer. I have a 420 Passage. I have Cruzair systems. And I am over 300 miles from the boat as I reply. But maybe I can help. Maybe not. Do you know where your AC pump is? It provides water for the AC. Mine is in the galley adjacent to the fridge and sink under a pull up board. You can find it with your ears. Listen for the hum when you turn on AC and pump. You must have one (pump) otherwise AC no go. Does water pump overboard when you cut the AC on? If it doesnt, not good. Just some work. If that intake is left open, where the pump is all the time, it will clog with algae, etc. Its like your stuffing box. Feel the housing on the pump, if its hot, its not getting water. To fix, you have to disconnect the line at the pump, turn it on, and shake, pipe cleaner, compressed air, you name it to unclog it WITH IT RUNNING.. I find that shaking the line from the pump downstream to units, unclamped, usually works. So to prevent this in the future, here is the shutdown checklist that works for me. AC or ACs on and pump running. Close the pump thru hull and casually walk to the panel (bout 10 seconds). Shut down the pump breaker and then AC breaker. The seawater clears the line. There is a thru hull or a big mistake by Hunter. Find it! Unless of course you have some completely different AC system (aftermarket) than most boats. Crap I have edited this about 17 times. IMHO, I would never tap off a head line for my lovely cool air in the cabin. Its common for Hunter to mislabel in the manual... its one size fits all.
Cheers
Got to love boating!
