Yes LO/AC is a protection for the unit…The control constantly measures input voltage, and will shut the unit off if the voltage drops below 100 volts for longer than 3 minutes (200 volts for 230 volt units)

One of the worst things for a compressor is to run on low voltage, and before digital controls, we had many compressor failures from running on low dock power…Today those type of expensive failures are almost non existent due to the protection…

If your boat has a meter in the main panel (most do) I would watch it to see what your voltage is with, & without A/C…if you see that meter go close to or below 100 volts then the problem is likely the Marina's or the Dock (you don't say if the boat is behind your house or in a marina) House docks tend to be worse because the guy who put in the power didn't plan for A/C type loads…

Certain times of day can be a problem too…Like when everyone else's A/C on the dock is working the hardest….The more load that is applied to that dock line…The lower the voltage will drop….

As far as why the others continued to run fine….Well once the salon A/C load was removed, the dock voltage raised a bit…

If you are in a marina I would have the dockmaster/electrician come & check your pedestal voltage while you are running all the A/C's…If it's low there…It's the marina's problem…If not…Read on…

Yes it could be in the boat and three A/C's at 115 volt is quite a load…Actually you likely have two 30 amp cords….Hopefully the installer did not put all three A/C units on one of those cords…If so, then one A/C should be moved to the other cord.

I don't know how handy you are, but the above gives you the general idea…You may need the services of a marine electrician, and Sometimes you have to practice "Power Management" by shutting off other things when all A/C is needed…Like the water heater, stove, or battery charger…all of which are power guzzlers…

It is a common problem on docks & in boats, and it's also possible that your Salon A/C control needs to be calibrated to the actual voltage that it is being given…The original installer should have done this, but often does not, though I don't think I ever remember seeing a control being off by more than a couple of volts with the factory default setting…

If you do find the control is shutting the unit off prematurely then I can tell you how to calibrate it, but you will first need a good digital voltmeter to read it's incoming voltage…. 

Steve~

Are these 115 or 230 volt systems ?

What kind/brand/model boat ?

Steve~