Discover Boating Get your Free Beginner's Guide to Boating 3

Winterizing Your Self-Contained A/C System

At the end of a glorious boating season, few owners want to think about preparing their boats for the winter, least of all the on-board systems, which are commonly forgotten. Although your air conditioning system becomes useless while your yacht is in the boat yard, not preparing it for the cold months ahead can cause problems or make a small issue a major concern when the warm months return – delaying your return to the water next year. To avoid lengthy summer preparation, be sure to perform vital maintenance during the fall.

Specifically designed to withstand the harsh conditions of the marine environment, self-contained air conditioning systems are commonly used on yachts of 30ft to 65ft, providing cooling, heating and de-humidifying capabilities within a compact and easy-to-install unit. Carrying out a few simple maintenance tasks prior to storing your boat for the cold months can go a long way in maximizing performance and longevity of the system and preventing A/C failure.


With self-contained A/C systems, a seawater pump circulates raw ocean water through the unit which can often pull in debris such as mud, seaweed, barnacles and plastic bags. Most materials are captured in the mesh basket of the seawater strainer (which should be checked daily or weekly during boating season), but microscopic organisms can get into the seawater cooling system. If left during the winter, seawater organisms can die off inside the unit, causing unpleasant smells and blockages. When the system is operational such blockages will inhibit sufficient water flow and prevent the unit from cooling, so debris must be removed before the boat is stored. This can be achieved by using lots of fresh water and high pressure to loosen debris and clean the strainer and cooling system.


One of the most common causes of A/C system failure is damage caused by water that has frozen and expanded over the winter. Therefore it is essential to drain the system thoroughly, including the pump and hose. Before draining, run fresh water through the unit for 5-10 minutes to wash away any remaining salt. If the boat is kept in the water for the winter, you should close the seacock attached to the water in-take hose.


There is always a chance that some residual water remains in the system, so to avoid freezing, you should run a little biodegradable antifreeze through the unit. Use a 50/50 nonpolluting biodegradable antifreeze/water solution. Any method that causes the antifreeze solution to flow downward is the method of choice. By this means, the antifreeze solution displaces any trapped water and eliminates the possibility of it freezing in hidden areas.Pump antifreeze solution into the overboard thru-hull fitting, and discharge through the intake thru-hull fitting.


Another winterization option is to use pressurized air to expel any trapped water from the system. You can either inject it at the seawater intake fitting to force system water through the seawater overboard discharge fitting, or use pressurized air injected at the overboard discharge fitting to force system water through the seawater intake fitting.In addition, since the seawater pump utilizes a magnetically driven impeller, remove the impeller from the wet-end assembly, wipe with an alcohol solution, and store in a warm, dry area until commissioning takes place.


Of course, if you ever come across a more serious problem with your air conditioning when winterizing your boat or when it comes to putting it back in the water, seek advice from your air conditioning system’s manufacturer.

Print | posted on Friday, November 04, 2011 4:16 PM