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What's wrong with my refrigerator?

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My refrigerator has not worked on electricity since I bought the motorhome. Only works with gas. When I light the flame it stays lit only as long as I am pushing the button on the front of the refrigerator for gas. but as soon as I release the button, the flame goes out. I see two pieces of rusted metal that turn orange when the flame is lit. They look rusty and as if they were once connected and are now separated. I think these are the components I need to replace here are some photos.

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So how do you know it works on gas when the flame won't stay lit????

There is a thing called a thermocouple it sticks into the flame and keeps the gas valve open when you release the button. Its a VERY common part.  http://www.adventurerv.net/dometic-refrigerator-thermocouple-rm2652-rm2662-rm3662-rm3663-rm4872-p-28133.html.

The thermocouple is the thing in the back.

The way the glowing thing in the front, is mounted, it looks more like its part of a piezo striker. Do you have a push button that you push to make a spark to start the fire?.

The two things are not connected.

Hers is a short video. https://www.youtube.com/watch?v=FCqiVqZx5k4

The cooling unit is the same for electric and gas. So if it works on one then the cooling unit is OK. Another video about the AC heater. https://www.youtube.com/watch?v=b2zioJ7XwmM

Edited by WME

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36 minutes ago, WME said:

So how do you know it works on gas when the flame won't stay lit????

There is a thing called a thermocouple it sticks into the flame and keeps the gas valve open when you release the button. Its a VERY common part.  http://www.adventurerv.net/dometic-refrigerator-thermocouple-rm2652-rm2662-rm3662-rm3663-rm4872-p-28133.html.

The thermocouple is the thing in the back.

The way the glowing thing in the front, is mounted, it looks more like its part of a piezo striker. Do you have a push button that you push to make a spark to start the fire?.

The two things are not connected.

Hers is a short video. https://www.youtube.com/watch?v=FCqiVqZx5k4

The cooling unit is the same for electric and gas. So if it works on one then the cooling unit is OK. Another video about the AC heater. https://www.youtube.com/watch?v=b2zioJ7XwmM

Thanks for the info and links. The button that is supposed to ignite the flame has never worked for me. I have to have my girlfriend press the gas button while I manually light the flame. Or, when she's not with me, as is the case now, I use a curtain rod wedged between a cabinet and the button in order to press the button and then  I quickly jump out and light the flame. Gotta move quick so that I don't get a big flame pop!

There is a lot of rust around the flue and burner assembly. I'm going to remove the burner tube and thermocouple and clean out any sediment. I read that I can test the thermocouple with a multimeter when the thermocouple is hot. 

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You can test the AC heater with a Multimeter, the thermocouple is mechanical in design and it works or it doesent. Its a tube with wax in it when the wax gets hot it expands and pushes a button that pushes the gas valve.

Piezo striker and spark tip  http://www.busdepot.com/camper-parts-accessories/camper-propane-stove-and-refrigerator-parts/refrigerator-part?limit=12 

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1 hour ago, WME said:

You can test the AC heater with a Multimeter, the thermocouple is mechanical in design and it works or it doesent. Its a tube with wax in it when the wax gets hot it expands and pushes a button that pushes the gas valve.

 

?????  You've got me confused.  Any thermocouple I've worked with makes electricity and when voltage gets over 30 millivolts - the gas valve turns on.  All someone has to do - to test a thermocouple - is stick it in a flame and read the voltage at the other end.  Set the volt-meter on the millivolt scale and when the thermopcouple is cold - it will read zero.  Once you start heating it up - voltage will climb often to over 50 millivolts. No "wax" inside and no mechanical operation. At least not in any thermocouple I've seen in any furnace or refrigerator.  Note that some mechanical temperature gauges like we might stick in the dashboard of a tractor DO have a mechanical-read setup.  None I've seen in RV furnaces or refrigerators. I just got done testing a thermocouple out of a Dometic 3-way.  0 volts cold and 60 millivolts hot.

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Here is a thermocouple AKA thermopile from a Dometic and one way to test.  I.e., with a propane torch.  Note zero volts when cold and up to 70 millivolts when red/orange hot as it should be.  The gas valves in any I've seen are the "millivolt" design.  That means the thermocouple is a small electric generator and makes all the electricity needed to energize the gas valve.  Some furnaces - especially in houses or newer RVs use battery power or grid power to energize the gas valve.  

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I guess my old RV was stone age, it used the same thermocouple as a old house hold water heater. Haven't had to check one on the new rig.

If you can check with a multimeter then great.

This is what I replaced in my unit http://www.homedepot.com/p/Honeywell-24-in-Universal-Gas-Thermocouple-CQ100A1013/202216463

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something else to keep in mind with thermocouples....because we're working in millivolts, ANY resistance at the connection is too much.  sometimes all it takes to "resurrect" an apparently dead one is to clean the threaded base contact with fine wirebrush and contact cleaner.

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I removed the thermocouple and burner tube. Burner tube had a lot of rust sediment inside. Cleaned it out with some denatured alcohol. Used a suggestion from another forum to clean the end of the thermocouple that sits above the flame with a pencil eraser. The other end had some yellow stuff inside the threaded piece that connects to the gas button. I cleaned that crap out. Put everything back in and wallah, the refrigerator is resurrected. Now maybe I should start investigating why it doesn't work on electric. Thanks for the help. This forum has been so good to me. Every day a new problem in the last couple weeks. Fuel pump went out in Joshua Tree with no cell reception. Fortunately I had the old electric pump that I took off last summer due to vapor lock. Put it back on to replace the seemingly malfunctioning mechanical pump I've had for just 8 months. Both of my 400 watt inverters crapped out. And the roof leak repair failed and is leaking again after heavy rain in sw Utah last night. SMH. But learning how to fix things is really fun. I've never been much of a mechanically inclined handyman until being forced to fix things myself on this motorhome.

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electric is easy. your wiring is 30 years old. it will need to be replaced almost assuredly. to see what I mean, cut it back with a knife. you will quickly discover that the copper is corroded and not conducting the current flow needed to run the heating element; or the heating element was damaged by improper current and also needs replaced.

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I "resurrected" a frig like this once by using compressed air to blow out the gas line...   afterwards, the flame was larger and the extra heat was enough to get the thermocouple to tell the controller "that there is heat present, don't cut off the gas".

 

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This is great info, as I have not yet fired up my refridge yet.

B

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