Originally Posted by jwnall
My Ocean Breeze water-cooled marine air-conditioner comes on normally and starts to blow cold air, but after a little bit shuts itself off. There is a line on the QU288 digital wall control which says "check filter." Anyone know where the filter might be located? Or any thoughts on why it would shut itself off? I'm not sure just exactly where to start.
The flow of cooling water to the A/C unit starts with the raw water pickup, which can become restricted with debris or marine growth. Next in line is the sea-cock which must be fully open, the raw water strainer which must be clean, the supply lines that must be unrestricted, the raw water pump that must be pumping, the A/C condensing coil and finally, the discharge fitting. They all must be all be clean and clear and functioning for the A/C unit to work well.
How long since the condensing coil has been cleaned? Even with what appears to be adequate water flow, if the interior of condensing coil is coated with scale or marine growth, it will not be able to remove the heat from the refrigerant. The compressor high pressure switch will cycle the system off to protect the compressor from damage.
You can back-flush the condensing coil with a garden hose. This will remove the loose stuff, but to really clean it you will need to use acid or one of the specialty products manufactured just for coil cleaning. I would definitely look this up in the owner's manual or call Ocean Breeze to get their recommended procedure for coil cleaning. Most manufacturers recommend cleaning/flushing the condensing coil annually or more often if the local water conditions require it. The chemicals can be pretty nasty too, so this might be something you want to leave to a pro.
Here is a source for Marine A/C troubleshooting information you might find helpful or confusing, as the case may be:
Marine Air Conditioning Forum, Advice and Store - Dometic Cruisair, Marine Airrrr, Air Conditioning parts and systems on yachts and boats
suggested, check the evaporator coil. If clogged or restricted, the evaporator can ice up and cause the system to shut down.
Those are the obvious things you can easily check yourself. Anything more and I would personally call a professional for service.