This is cross-posted from my message on the Facebook C320 group. If you'd like to see the pictures, hop over there and have a look at my post dated today.
After 24 years, the OEM refrigerator compressor on my C320 failed. I thought it had just died of old age, natural causes. Until recently, when I removed it to make way for a replacement unit. When I really dug into the repair, found that the entire thing was suffering from rust and corrosion. It became clear that a water leak of some kind was happening. So I immediately assumed that the propane tub above it was somehow responsible. That would turn out to be true, though the actual issue was far from simple.
It turns out that Catalina has a thing for screened vent fittings which was the undoing of my refrigerator.
I'll explain... The first thing I suspected was that the propane tub was in need of rebedding in the deck. After careful examination, it was clear to me that the tub itself is not leaking around its flange. So my next test was to see if the drain hose at the bottom was dripping water. I put some water in the propane tub to wash out the accumulated dirt and test the drain hose for leaks. I was surprised to discover that the drain hose was clogged. I tried to blast it clear with the pressurized water, but it wouldn't drain.
But still not a drop of water leaking out of any of the drain hose fittings above where the fridge compressor lived. While I had my arm in there feeling around the hose fitting, a drop of water landed on my arm in a different location. Meanwhile, another drop of water formed on the wires that run up to the propane solenoid, which is located inside the tub. The wires pass through the fiberglass through a rubber grommet (circled in red in the photo) and when I sprayed water in there, I also was trying to wash down everything, so I had water everywhere, including around the top of the compartment. It turns out that the rubber grommet around the solenoid wires was leaking.
But how could that leaky rubber grommet which was located in a place where water runoff shouldn't collect, be the cause of so much damage? Then it hit me. With the drain hose clogged, water was slowly accumulating in the tub, filling it up, and then when the level of the water reached the grommet, it would start a steady drip into the area below. It doesn't even take that much water to fill it up with a propane tank in there, because the tank displaces most of the volume of the space.
So I traced the drain hose and located the through-hull drain fitting at the back of the sugar scoop transom on the port side. What I discovered was that this is the same type of fitting that they used on the holding tank vent, complete with a screen. Of course, the reason the tub wouldn't drain was that over the years, dirt had accumulated in the propane tub and washed down the drain, slowly clogging the through-hull until it would no longer pass any water.
So there you have it. A fitting that is meant to be a drain line to pass accumulated rainwater had a screen on it... Poor design choices by Catalina caused the refrigerator to die a watery death. In the attached photo, you can see a sampling of the muck that I scraped out of the through-hull. In my opinion, this fitting should only be used as an air vent, and not one that will also have water draining through. Especially if that water could have dirt and debris mixed in.
I had cautioned in an earlier post that I thought the propane tub was the culprit, but I figured a follow-up would be useful since the actual diagnosis turned out to be different than I expected.
The moral of the story - Check for proper drainage of your propane locker. If the fitting is clogged, it can be cleaned out, but since I had to remove it, and the original fitting wasn't in great shape anyway, it is being replaced with a mushroom-style through-hull that does not have a screen. I will also be replacing the rubber grommet with a new one.
Not only is a clogged drain a safety issue because any leaked propane doesn't have an escape path, but the resulting collection of water can cause other damage as well once the tub fills up.