3 way fridge on propane doesn't cool

[Cheri B.]

Troubleshooting dometic 3 way fridge on propane - stays lit but doesn't cool

My Dometic 3 way refrigerator works on Shore Power. However, it isn't cooling when switched to propane. We've taken the propane lines out and cleaned them, made sure there's nothing interfering with the flow of propane. The flame is steady and blue and stays lit for days but the refrigerator does not cool. Since it works fine on Shore Power, what else can I check? I've watched youtube videos and tried everything I've seen there. The camper is level. It is set on "high" and "7" although I've tried other settings as well. Thanks for any insight! I am planning to boondock next week!

 

[SteveP]

First guess would be wasp nests blocking the flue not allowing the heat to get to the boiler. May be difficult to clean out. Run a bottle brush from the top and bottom to knock out the big stuff and blow it out with compressed air.

Sounds like the flame is good but just to make sure, it should be a perfect teardrop shape. Any indication of soot would mean that the burner tube and orifice need to be cleaned. Blow the burner tube out with compressed air. Soak the orifice in alcohol over night and blow through it with compressed air. Don't push anything solid through the orifice because the soft brass is easily deformed.

 

[Cheri B.]

First guess would be wasp nests blocking the flue not allowing the heat to get to the boiler. May be difficult to clean out. Run a bottle brush from the top and bottom to knock out the big stuff and blow it out with compressed air.

Sounds like the flame is good but just to make sure, it should be a perfect teardrop shape. Any indication of soot would mean that the burner tube and orifice need to be cleaned. Blow the burner tube out with compressed air. Soak the orifice in alcohol over night and blow through it with compressed air. Don't push anything solid through the orifice because the soft brass is easily deformed.

Thank you! We did soak the Orifice and blow it with compressed air yesterday. I don't hear the flame, so I do think that's the issue somehow.

 

[Grandpa Don]

I agree with SteveP. But, you said that the setting knob was on 7 when running on propane. You probably already know or have done all of this, but I'll repeat it anyway. That knob is for when you are running on 120 vac. The knob labeled Low, Med, and High are for propane control. Make sure that it is set to High. and make sure that the other power sources are not selected. DC and AC should be off.

Remove the little burner and clean it and the orifice located just inside the tube. It is a very small hole, so it doesn't take much to plug it up. Don't try to enlarge it, but run a bristle off of an old wire brush through it. Those are generally small enough. Look at the hole with a magnifying glass and a light. It should be perfectly round, but very small. Be careful putting the orifice back in. It only goes one way and tends to fall out of position when you attach the propane tube back on. If you tighten up the propane tube with the orifice misaligned, it will crush it and make it useless. Be careful.

Can you take a photo of your control panel knobs, and of the flame? You might have to remove a cover to do that, but I would like to see that flame.ff

 

[Grandpa Don]

Thank you! We did soak the Orifice and blow it with compressed air yesterday. I don't hear the flame, so I do think that's the issue somehow.

I just saw your second post. But I want to repeat. Make sure that the little hole in the orifice is perfectly round. My cousin ordered a replacement orifice from Dometic last year, but it did not cool down properly after installation. We had to take the burner apart while in camp to figure out why. It turned out that the new orifice hole was not punched properly right from the factory. You could only see the obstruction with a magnifying glass and a light. We made the mistake of trying to open it up with a needle, which was way too big. After that, we had a blowtorch back there. You could hear that burn from 6 feet away. Needless to say, we did not use propane for the rest of the trip for fear of burning the camper down.

 

[Cheri B.]

I just saw your second post. But I want to repeat. Make sure that the little hole in the orifice is perfectly round. My cousin ordered a replacement orifice from Dometic last year, but it did not cool down properly after installation. We had to take the burner apart while in camp to figure out why. It turned out that the new orifice hole was not punched properly right from the factory. You could only see the obstruction with a magnifying glass and a light. We made the mistake of trying to open it up with a needle, which was way too big. After that, we had a blowtorch back there. You could hear that burn from 6 feet away. Needless to say, we did not use propane for the rest of the trip for fear of burning the camper

I agree with SteveP. But, you said that the setting knob was on 7 when running on propane. You probably already know or have done all of this, but I'll repeat it anyway. That knob is for when you are running on 120 vac. The knob labeled Low, Med, and High are for propane control. Make sure that it is set to High. and make sure that the other power sources are not selected. DC and AC should be off.

Remove the little burner and clean it and the orifice located just inside the tube. It is a very small hole, so it doesn't take much to plug it up. Don't try to enlarge it, but run a bristle off of an old wire brush through it. Those are generally small enough. Look at the hole with a magnifying glass and a light. It should be perfectly round, but very small. Be careful putting the orifice back in. It only goes one way and tends to fall out of position when you attach the propane tube back on. If you tighten up the propane tube with the orifice misaligned, it will crush it and make it useless. Be careful.

Can you take a photo of your control panel knobs, and of the flame? You might have to remove a cover to do that, but I would like to see that flame.ff

 

[SteveP]

I don't hear the flame, so I do think that's the issue somehow.

You shouldn't be able to hear the flame.

 

[Cheri B.]

That's helpful because I didn't know which knob controlled the temperature! I've tried all settings though. I can see that high makes the flame burn a little bit brighter so I've left it there. I'm attaching pictures. I'd love you to take a look. I have to wait for my friend to come back to take it apart to look more closely at the orifice though. It's hard to get out of mine after it is unscrewed.

Let me know if these pictures aren't clear enough. I'd be happy to take more. Thanks so much for the help!

 

[Cheri B.]

You shouldn't be able to hear the flame.

Thanks, I've read varying information on this so that's good to know.

 

[Cheri B.]

This is definitely worth looking into as it looks like the propane part of the refrigerator has never been used. It's a 2005 and I purchased it 3 years ago and I've always used electric for it. We looked at it, but need to look with a magnifiying glass. It did have a spec of dirt in it and once we blew it out I could see light coming through the tiny hole but I don't know if it was round.

 

[SteveP]

I'm not familiar with that burner but the flame on my Norcold, when it's right, is a perfect teardrop shape and over an inch tall, close to an inch and a half. I don't think you should see the flame at the bottom of the burner. This leads me to believe that the burner itself is blocked. Little spiders like to build nests in propane burners. The fact that the flame is blue indicates to me that the orifice may be ok, your gas/air mixture is right. Clean the burner from the vent to the tip and see if that helps before messing with the orifice again.

 

[Cheri B.]

I'm not familiar with that burner but the flame on my Norcold, when it's right, is a perfect teardrop shape and over an inch tall, close to an inch and a half. I don't think you should see the flame at the bottom of the burner. This leads me to believe that the burner itself is blocked. Little spiders like to build nests in propane burners. The fact that the flame is blue indicates to me that the orifice may be ok, your gas/air mixture is right. Clean the burner from the vent to the tip and see if that helps before messing with the orifice again.

Thank you very much for taking a look! Will do! Thank you again for the replies!

 

[Grandpa Don]

That's helpful because I didn't know which knob controlled the temperature! I've tried all settings though. I can see that high makes the flame burn a little bit brighter so I've left it there. I'm attaching pictures. I'd love you to take a look. I have to wait for my friend to come back to take it apart to look more closely at the orifice though. It's hard to get out of mine after it is unscrewed.

Let me know if these pictures aren't clear enough. I'd be happy to take more. Thanks so much for the help!

I have never seen a flame that looks like that one! I don't know what the deal is, but something doesn't look correct there. My Viking is a 2003 model with the same Fridge, and my flame is nothing like that one. Maybe someone else can figure out what the difference is. Take another look at that orifice. Make sure that hole is very small. Almost the same size as human hair.

Whatever it is, I still think the burner and flame are the issues. Pull that burner out again and let's take a close-up look at it. (Photo). I think we are on the right track.

 

[GaWalker]

I am fighting the same issue with my 2003 Dometic RM2353 - which does have a different burner. My wife broke the thermocouple probe while cleaning the inside of the fridge. I replaced the Thermostat (which includes the thermocouple) and the fridge worked fine but I do not think I ever tested gas operation until while on a long trip. The fridge did not cool on gas. I have now cleaned out the orifice, burner and flue with no success. The pilot flame looks good but the flame is not increasing when it should. My current theory is that the thermostat is not properly increasing the gas flow.

 

[Anthony Hitchings]

GaWalker - check your frig manual - you may find out that the thehmostat is only for operation on 120VAC, not gas, as it is with my 3-way Dometic frig.

 

[GaWalker]

GaWalker - check your frig manual - you may find out that the thehmostat is only for operation on 120VAC, not gas, as it is with my 3-way Dometic frig.

The gas flows thru the thermostat on my model. There is no separate switch for gas.

 

[xxxapache]

Cheri B.

You can't judge gas flow by looking at the flame. You need to test the gas pressure using a manometer. It's possible your regulator needs adjusted or replaced.

 

[Lug_Nut]

Cheri B., The flame at the expected location as shown in your 'controls' photo looks quite large in comparison to the flames I've seen on the three different fridges I've run on LP. Each of those had a cylindrical shaped tube that is closed at the end, with 'slices' cut in the tube to make several outlets for the air/gas mix. The air/gas tube is usually a galvanized steel to resist the rust that forms when the hydrocarbon gas combines with oxygen. (basic chemical reaction of HC + O2 = CO2 + H2O + heat). The galvanizing is not present on the exposed steel where the 'slices' were cut afterward. Rust that started in the sliced gaps will expand and may have caused the individual slices to merge into one big hole. That would affect the flame and could make it take on the apparent size of your image. Re-check the tube where that flame is formed to be sure that there are several, equal width 'slices' partway through the tube diameter.
Another puzzle is the other blue spot in that image. Is that a reflection of the burn tube flame off a glossy surface? If it is that burn flame is even larger than I imagined. If that is actually a second flame, I don't think it should be present. It may well indicate a propane leak. Were that a second gas release location, and that flame were to blow out, you have unburned propane being released and collecting in an area of a flame. That is very dangerous.

GaWalker., There appear to be three thermostats, one for 12VDC, one for 120 VAC, and a pressure operated 'thermostat' for LP. That's based on the electrical schematic shown on page 10 of this pdf. I didn't see a plumbing schematic to determine if the gas control based on that 'thermostat' output is by electric solenoid actuation or by thermal expansion of a liquid through a capilary tube.

https://techsupport.pdxrvwholesale.com/wp-content/uploads/2017/09/Dometic-Refer-Model-RM2353-Installation-User-Manual.pdf

an excerpt from that pdf:
"When the thermostat reaches the set temperature, it will cut the burner back to bypass or, in electric operation, shut off the heating element."
Based on that schematic, and your reported symptoms, I'm leaning towards the gas valve that opens and closes the burner gas supply (not the bypass gas for the continuous pilot) as not operating as intended.

 

[GaWalker]

Cheri B., The flame at the expected location as shown in your 'controls' photo looks quite large in comparison to the flames I've seen on the three different fridges I've run on LP. Each of those had a cylindrical shaped tube that is closed at the end, with 'slices' cut in the tube to make several outlets for the air/gas mix. The air/gas tube is usually a galvanized steel to resist the rust that forms when the hydrocarbon gas combines with oxygen. (basic chemical reaction of HC + O2 = CO2 + H2O + heat). The galvanizing is not present on the exposed steel where the 'slices' were cut afterward. Rust that started in the sliced gaps will expand and may have caused the individual slices to merge into one big hole. That would affect the flame and could make it take on the apparent size of your image. Re-check the tube where that flame is formed to be sure that there are several, equal width 'slices' partway through the tube diameter.
Another puzzle is the other blue spot in that image. Is that a reflection of the burn tube flame off a glossy surface? If it is that burn flame is even larger than I imagined. If that is actually a second flame, I don't think it should be present. It may well indicate a propane leak. Were that a second gas release location, and that flame were to blow out, you have unburned propane being released and collecting in an area of a flame. That is very dangerous.

GaWalker., There appear to be three thermostats, one for 12VDC, one for 120 VAC, and a pressure operated 'thermostat' for LP. That's based on the electrical schematic shown on page 10 of this pdf. I didn't see a plumbing schematic to determine if the gas control based on that 'thermostat' output is by electric solenoid actuation or by thermal expansion of a liquid through a capilary tube.

https://techsupport.pdxrvwholesale.com/wp-content/uploads/2017/09/Dometic-Refer-Model-RM2353-Installation-User-Manual.pdf

an excerpt from that pdf:
"When the thermostat reaches the set temperature, it will cut the burner back to bypass or, in electric operation, shut off the heating element."
Based on that schematic, and your reported symptoms, I'm leaning towards the gas valve that opens and closes the burner gas supply (not the bypass gas for the continuous pilot) as not operating as intended.

There is one capillary thermostat which both switches the electricity (as shown on the schematic) and the gas. The gas flows thru a valve connected to the mode connector switch, the thermostat, the safety valve(with push to start) the to the burner. I have not been able to find any info on the operation of the thermostat but there is no reason to run gas line thru it if it can not control the flow.

 

[Lug_Nut]

GaWalker, I don't have your advantage of the physical unit, nor the documentation that might have come with it. I found online what I think is a representative image and I can see the gas piping connected to the thermostat in that image. That image matches your description so I believe I have a clearer idea of what you have in your fridge.

https://www.arprv.com/image-arp/dometic-rm2352-rm2353/rm2353-rm2453-wiring.jpg

What I don't identify from that image is the supply of gas to the pilot flame, but since you stated the pilot is operational, I can discard a complete lack of gas as possible cause for the problem.
Does your unit have a separate flame for a 'pilot' and a main flame for heat? Or does it simply turn down, but not completely extinguish, the heat flame when the fridge is sufficiently cooled? That answer makes a difference in my prior thinking about a dedicated supply to a separate pilot flame.
I'm suspecting, as you mentioned you were, that the knob controlled thermostatic unit is not opening the gas valve for the full flow of gas needed for sufficient heat to effect cooling, that the valve remains at 'idle' supplying no more than the gas flow needed to maintain the pilot.