Maintaining a proper charge is very important for the system to work efficiently either way. A good way to check how well your system is doing as an air conditioner is to is place the back of your hand over one of the grills it should feel cold. If it feels cool it may not be getting as cold as it should and might need some attention. The same goes for the heat mode if it feels lukewarm, it may not be getting as warm as it should. We are taking the heat out of our cold North West water sometimes getting below forty degrees. At this point the system is working at it maximum. A full charge of refrigerant is especially important. In the cold environment the system is working at a low pressure. It is not uncommon for the low pressure switch to cut out, and will show a low pressure fault on the panel. This is a good indication of a undercharged system.
One other important part of the system is water flow. Keeping the sea strainer free of debris is very important to system operation and checking water flow at the water outlet is the first thing to check when having any problem. If your control panel indicates an over pressure or high heat problem it is most likely a water flow issue, again check the sea strainer and water inlet at the haul. Make sure the seawater pump is cumming on. Check the breaker on the panel if it has one, before calling for help. It will save you a lot of money. It may be the pump needs replacing or the condenser is in need descaling.
If so call me I will be happy to come out.