Spent almost all day futzing with the fridge. I think I know what’s going on but not quite sure how to go about fixing it. The Frigoboat reefer is a capillary tube system. That means that refrigerant is pumped by the compressor through a teensy little tube (the capillary tube) putting it under very high pressure. When it reaches the evaporator plate inside the fridge, the tube suddenly gets bigger. The drop in pressure allows the refrigerant to boil. The refrigerant (freon or whatever they use now) boils at a very low temperature but it still takes heat to make it boil. The heat, in this case, is supplied by the ambient air inside the fridge box. Boiling the refrigerant pulls heat out of the box, thus lowering the box’s temperature. Or at least that’s how I understand the process. Anyhoo, the spot where the capillary tube meets the bigger tube, at the evaporator plate, is a spot where oil, water or dirt can cause an interruption in the flow of refrigerant. No flow, no cooling. And that’s where we seem to be.
How did I come to that conclusion? Well, when the refrigerant is flowing, you can hear it. It’s quiet but if you listen close you can hear the gurgling of moving liquid. However, we haven’t been hearing that lately. Today, I happened to bump the capillary tube where it makes the transition to the big tube and suddenly I heard the gurgling sound and immediately the evaporator plate started to cool down. After a couple minutes, the gurgling diminished and then stopped altogether and the frost on the plate melted.
I’m pretty sure that dirt isn’t the issue as it doesn’t fit in with the symptoms in the book. Dirt would plug the other end of the capillary tube, not the place where it suddenly gets bigger. That leaves either oil or water. The book says that the only way water would get in would be through faulty service or a leak. Pretty sure we don’t have a leak and the system hasn’t been opened since I first installed it back in 2009. Oil, on the other hand, sounds like a likely option. Apparently there’s a little bit of oil in the refrigerant but it should pump through the system just fine. However, to quote the manual:
This is most likely to occur in freezer systems that have seen continuous or near continuous trouble-free operation for
several years and either; (a) after the evaporator is defrosted with a high temperature heat source (hair drier, heat
gun), or (b) after the vessel has been left unattended and closed up in a hot environment.
Other than the fact that ours is not a “freezer system”, (b) pretty much matches our situation. So, what to do? Well, the book says to apply heat to the capillary tube in the form of a hot, wet cloth. This is supposed to expand the tube and lower the viscosity of the oil, allowing it to flow more freely. So, I tried it. Boiled some water, wet a cloth with the hot water and, with tongs, held it to the cap tube for a couple minutes. And you know what? It worked. For a few minutes. Then the flow stopped and the plate thawed. The book says you may have to do this a number of times before the situation returns to normal. So, all afternoon, Lulu and I applied hot wet cloths with varying levels of success. Sometimes it worked for a minute or two, sometimes for several minutes. Finally I decided to screw the wet cloth. Let’s get serious. We filled a shot glass with boiling water and dipped the cap tube in it for a couple minutes. I’ll show you tube expansion! I got your viscosity-lowering right here! And it worked! This time it worked for quite awhile, maybe twenty minutes or so. We thought we had it dicked until it suddenly quit again.
Throwing in the towel for today, we loaded the fridge with ice, turned the compressor off and will try again tomorrow. Maybe, by leaving it overnight, it will miraculously heal itself. Could happen. Right?
Oh, and by the way, the fridge was left on the whole time we were gone (3 months). It must have worked OK until just before we got here because the beer was still very cold but Lulu said the plate looked like it had been defrosted.
So, my two big challenges for tomorrow: make the fridge work right and try to stow all our crap without resorting to stowing it on the cabintop again. The cabintop looks so nice right now without a bunch of stuff on it and I’d really like to keep it that way so I’m going to have to do some creative thinking to come up with alternative stowing.
PS: for those who think we need more refrigerant, the test is supposed to be: if the plate ices over completely and evenly and the return tube doesn’t ice up at all, the refrigerant is right. Well, when things are flowing, that’s exactly our situation so I doubt refrigerant is the problem.
to be continued….