We’ve been doing quite a bit of traveling lately. As a result, Eagle Too hasn’t been getting quite as much attention as she usually would. After returning from a recent trip to Disney World (we’re making the most our Florida resident annual passes!), we stopped by the boat to see how she was doing.

Unlocking the companionway and dropping into the cabin, we immediately noticed that the air conditioning wasn’t running. We normally leave it at 78° when we’re not onboard, to keep the boat dried out and resist the development of odors. But the AC wasn’t working, and the control panel was displaying the dreaded HPF code. A High Pressure Freon (or High Pressure Fault) code is usually a sign that the seawater suction strainer is clogged and the unit isn’t getting adequate cooling water flow.

Sure enough, our seawater strainer was completely clogged. But after cleaning the strainer and flushing some fresh water though the lines with a hose, we still couldn’t get the AC system to run for more than a few minutes before shutting down again with an HPF fault, even though we had good water flow through the system.

Something else was wrong. Some research indicated that we most likely had marine growth in our condenser, preventing the system from being able to properly cool the circulating hot refrigerant, creating a high pressure fault.

The next step here would be to do an acid flush of the seawater system to dissolve the internal growth and scale. But that requires re-plumbing the air conditioner to recirculate an acid solution to/from some sort of container, usually using a small submersible pump. I thought there had to be an easier way.

Here’s what I came up with. The first step was a quick stop at Harbor Freight to pick up a $6 fluid transfer pump.

Then I made a run to West Marine to buy a gallon of Barnacle Buster. It’s a product that’s made specifically for flushing marine sea water systems in a non-toxic, environmentally safe way. And unlike muriatic acid, the usual go-to product for air conditioning and engine flushing, it won’t harm the plastic, rubber and metal parts in your system if you let is sit and soak for a good long while.

I then picked up a couple of hose adapters so that I could remove the air conditioning sea water suction line from the seacock and connect the hand pump to the line.

Dropping the pump suction into the open bottle of Barnacle Buster, I then pumped a half gallon of the solution into the system (until we were pretty sure we were getting some out of the overboard discharge). Then we buttoned up the boat and went home.

After letting the solution soak in the system for 24 hours, I disconnected the hand pump, hooked up a water hose, and flushed out the line with fresh water. About a gallon of nasty black yuck with embedded chunkies came out the the overboard discharge. After flushing the system until it ran clear, I hooked the sea water suction back up, and turned on the AC.

Rhonda and I broke out a deck of cards and settled into the salon to play a game of 3-13, a version of Rummy that some cruisers we met in Great Exuma taught us. A full game takes about an hour, and the AC purred flawlessly the entire time. After playing the last hand without a single AC hiccup, we were pretty darn sure we’d solved this particular problem.

I guess the best part of all this is that for less than $20 in parts, we now have a rig onboard that we can use for routine system flushes in the spring and fall, something we’ve never bothered with before.