cabin cool down when you run your air? I just tried out my new Mermaid 5200btu ac unit this weekend in the 353 and was a little disappointed. It ran straight for hours and never dropped them temp significantly. I put a digital thermometer in the supply vent and verified the temp at 64-65* (day). At night the supply temp got as low as 59* but it takes quite a while to drop that low. With an outside temp of 85* my cabin never dropped below 77*. Is this normal? I hear people tell me their ac will freeze them out, not mine? Should the unit be blowing cooler? Also, should the unit run for hours straight?

Try a small DC fan near the vent to circulate the air. It sounds like the fan moving the air is not strong enough to circulate.

My cabin cools down in a few minutes, once I turn on the AC.

Mine cools down in 10-15 mins

mine cools down pretty quickly, but i have a 7500 btu with 2 supply vents.

I don't have A/C on my boat but it sounds to me that you have a problem. A typical ac will put out at least 15 * cooler air than it's return. Possibly the problem is simply the return air is mixing with the hot outside air. If you can get to the condensing unit I would at least feel the larger line going into the compressor, it should be cold to the touch. If not you may have a problem. Also you may want to check your sea water lines for a strainer which may be plugged up.

If you have poor airflow typically the discharge air will be excessively cold this doesn't sound like the case unless the coil is froze up, then the airflow has been blocked by the ice. Try to turn the unit off for a few hours, try it again with the therm. and see what you get. If it has more airflow and a high temp. drop then you may be freezing the coil and need a tech. to check it out.

Good luck

I was told that my a/c would only be 10* below outside temp.i have a 5000 btu on the 37'

12,5K in my 28. I can make it snow. Drops 25 degrees in a 1/2 hr with the fan all the way up.

Sounds like you need to bring the boat to the dealer and let them figure out the problem. Hopefully it's under warranty.

After talking with Mermaid tech support they said "if it blows 18-20* colder than the ambient temp, thats the definition of ac".