I had a problem with my salon AC unit switching off too quickly, when I was at Great Oak Landing recently with Blue Note. The compressor for this unit is in the engine room, and the evaporator/airhandler is in a locker in the head and ducted up to the salon. The cold air goes upward at the port side of the triple windshield, and then across the ceiling of the salon. This is a 16Kbtu unit. Even though it was 98 degrees outside, the salon unit kept switching off. These units have been updated with digital controls.

Annapolis CruiseAir came out and looked both AC units over. Pressures and charge are fine (the forward unit is now forty years old, it was OEM in the boat!). It turns out that the sensor for the control of the compressor is mounted on the digital control itself, and on the salon unit, the control panel faces upwards, and is close to the supply air outlet. The cold air was falling on the control panel and prematurely switching the compressor off.

The CruiseAir tech fitted a remote sensor which is installed in the return air grille, so that when it senses that the return air is cool enough it will switch the compressor off. This seems to have done the trick. I also found out about a film that 3M makes which will block a lot of the heat coming in through the windows; I'm working on that one.

I thought Annapolis CruiseAir did a good job. They aren't cheap, but they knew what they were doing, cleaned up after themselves, and communicated well and promptly. PM me if you want details or contact numbers. (the digital controls were installed by another company, but when I tried to get them to come to the boat and check it out this time, they didn't call back, etc etc, so I tried ACA on the advice of a friend who does yacht electrical systems)