3way fridge not working on 12V

[Tim Wood]

Sounds like you are nearing an end to the problem. Keep us updated

[Lloyd (aka Santa) Coltman]

Some heaters are wraparound, some cylindrical insert (those might be a b---ch to remove after all these years). I actually had to split the mounting tube on my old one (the element was rusted in). RVmobile.com has a lot of different types available. I agree, if you can get the parts, and get the old out easily, a little higher wattage would be better, at the expense of shorter battery life. Personally, I would rather go with your idea of running with the inverter, and leave well enough alone. You could probably re-use the old 12V supply wiring to power it. You really should read the info at www.RVmobile.com. Then you'll have a good understanding of how these things work, and what's critical. Ho-Ho-Ho!

[Rick G]

Thanks to all who chimed in. I tried to discover the root of the problem without removing the fridge on Wednesday, but was not successful. The access wires to the 12V heater still gave me about 2.5 - 2.6 ohms resistance. It appears that I will have to pull the fridge out and have a go at it, which I will do this winter.

For now I will run on the inverter when I need to get cooling from a 12V battery.

If I can replace the heater, all well and good. However, since the heater does actually heat, I may be able to make it work if I increase the wattage or heat transfer. Since the current and resistance are apparently fixed, the only ways to do that appear to be (1) improve the heat transfer to the cooling tubes as mentioned above to make sure it is maximum, or (2) increase the voltage from 12 V to 18V by adding a 6V battery in series. Since the only other things we have in the trailer that run on 12V are lights, this may work. However, I am not crazy about adding another battery, and may very well run through the inverter if it comes to that.

So, this brings the odyssey to a pause for now. I will try to pull the fridge around November to see what gives. Part of me wonders why I bother, since I have a work-around, but actually I get irritated by things that don't work properly, so I will probably keep at it until I have a solution some day.

Thanks,
Rick G.

[Rick G]

Well, today I finally got around to pulling the fridge out of the trailer. When I got a look at the back, I found that the heater element is a single copper cylinder about 4 1/2 inches long and about 5/8 inch in diameter, made by A.Birch & Co, somewhere in England. It slid easily out of the surrounding tube that attached to the refrigerant tubes. It was not held in by any paste or other sealant, and this seemed ot be the original configuration. It was next to the propane heater tube, which was also attached to the same refrigerant tubes. There was no significant rust anywhere that I could see. So, question 1 was answered, in that there is only one refrigerant tube and all the heaters heat up the same refrigerant.

The heater element has 4 wires sticking out of it, so both the 110V and 12V lines run the same heater. There are likely two elements in it, but there is no way to separate them out or replace just one.

I took the opportunity to clean the gas nozzle with alcohol and tidy things up a bit, then got to work on the 12V line. The ohms measurement across the 12V wires was 4 ohms, at the point where it connects to the trailer. This, as noted last summer, is not sufficient to get me to 75 watts. I need about 2 ohms to get 75 watts out of a nominal 12V line. So, I opened up the control panel where the 3-way switch and the thermostat reside. I disconnected the line that goes directly to the heater element and measured the resistance. It was 2.2 ohms across the heater element. This looked promising, as a 13 volt battery would give me about 75 watts. It also meant that I was losing 1.8 ohms across the 3 -way switch and thermostat wiring. Since both those components should be essentially 0 ohms resistance, it was probably bad connections.

So, I took all the connections apart and cleaned them. When I put the whole mess back together, I was getting 2.2 to 2.3 ohms across the whole system. This seems pretty close to the required load.

So, I replaced the all the parts and put the fridge back in the trailer. It seems to be working, but I will see how it does for a few hours. I put a glass of water in the fridge and will see if it gets cold. Anyway, I learned two things: if this doesn't work I can't replace just the 12V heater, and dirty connections can make a big difference.

All in all, I learned a lot today and am glad that i tried to fix it, even if it ends up not working.

Rick G in Alberta

[Bill MacDermod]

We have a 1999 Casita SD. I tried using our fridge on 12v on the very first trip in 2003 and it more problems than it was worth. It was the only thing I have found in 7 years that I didn't like about the Casita. I refused to even fool with it since. Propane when traveling and dry camping and 110v in parks, works like a dream.

[Otto]

Make it work on propane. We had the trouble of the flame blowing out and the frig not working, while driving. A friendly RV store near Dayton, OH checked the LP pressure and adjusted it properly. It was 8, when it should have been 11 or something. Worked perfect -- and it was free.

[Rick G]

Make it work on propane. We had the trouble of the flame blowing out and the frig not working, while driving. A friendly RV store near Dayton, OH checked the LP pressure and adjusted it properly. It was 8, when it should have been 11 or something. Worked perfect -- and it was free.

Yes, the fridge does work fine on propane. I solved the flame-blowing-out problem by putting duct tape over the closest two of the four vent panels in the lower access door, which reduced the wind while driving. I put it on the inside so it does not look bad. There is still plenty of air from the other two vent panels and the entire upper vent so the gas flame has air to burn.

A good idea about the regulator. Our regulator is original (1974), so I will get it checked this year. However the furnace gives me a good steady pilot flame with a hint of roar, so I think it is probably OK.

It turned out that the coldest 12V setting on the fridge gave me a 1/4 inch layer of ice on the top of a glass of water after four hours or so, so I took that as a sign it was working (though not as efficient as the 110V). I plan to use the 12V generally only when gas is not allowed while travelling, such as on the west coast ferries. However, I am contemplating a fair size solar setup, so it may be used more often. However, usually we would use gas or 110V if available.

Regards,
Rick

[Otto]

Ours had tape on the inside of the lower row, too. Thought this was from the factory.

[Jon Vermilye]

One good check for a heating appliance is to check the voltage across the heating element while it is on. There will be some drop from what is measured across the battery, but if it is excessive, look for poor connections, undersized wire, etc.