I have a 1989 Eastern Marine AC/Heat unit installed in my 1968 Chris Craft 38 Commander by the previous owner.  Cannot read the nameplate regarding size, but the unit is small.  But I am on Lake Superior and don't need AC very much.  The problem is that the unit usually starts up with the compressor and water pump going, but after a minute or two, the water pump and compressor shut down while the fan keeps running.  I had an AC tech look at it.  He said that the freon charge was good but that the temperature sensor at the air intake (or maybe another sensor)  was apparently shutting the pump and compressor down to keep it from freezing up.  I moved the sensor away from the air intake and held it in my hand to warm it, but that didn't seem to help.  The control unit is rotary with positions for cool, heat and fan only and a reset button.  A green light indicates when the pump is running and goes out when the pump stops.  The compressor also stops then.  The reset button will sometimes turn the pump and compressor on again, but only for a minute or two.  I am having trouble finding any information on the Eastern Marine units.  Would appreciate any advice.