Dometic Fridge not running on Propane - Pulled it out and see this

[jami20]

I've been having an issue with my Dometic fridge running on propane. When it's on AC everything works normally, but on propane I get nothing. I had changed out the regulator, and made sure everything was working at the flame - everything there was fine.

So today I decided I would pull out the whole fridge from the cabinet since I need to run some cable for solar anyway. I thought I would try to clean out the flue. And when I pulled the fridge out I see that the line close to where the flue is is really rusted. (I'm not sure what that line is, but I'm attaching pics so I hope some of you can help me there.) Could this be what's causing the fridge not to run when using propane?

(Sorry that the photos are rotated in the wrong direction. For some reason when I attach them they keep rotating to the left 90 degrees?)

[AWCHIEF]

No idea about the fridge problem.
Down sizing the pics usually gets them to post right side up.

[TG Twinkie]

The rust is a result of the heat created by both the burner and heating element. If it works on electric the boiler system is OK.
I think you may have either a bad thermostat or a clogged orifice not allowing the flame to max out. My old refer in the '74 Argosy would not cool sufficiently on gas. I found there to be a filter in the gas line which was plugged to the point where very little gas would pass. I don't know if your refer has such a device. The filter looks very similar to an in line fuel filter (metal of course) barrel shaped with a threaded fitting on each end. It was quite a challenge to remove it because of the closeness of the components up and downstream.
I could not locate a replacement. So I dug out the filter medium from the old unit. Which was totally saturated with an oily type substance. The only thing I could come up with for new medium was a cigarette filter. The refer has been running fine for 3 years. It has none of the fancy electronics.
If you can get your hands on a regulator (eBay) you could bench test it with a tank from the BBQ. Much easier to work on out of the coach.
If the refer has not cooled down. When you adjust the thermostat for colder temp you should hear and maybe see the change in gas flow, flame size. If not look for the reason why.
Plugged orifice etc.
Good Luck

[CRH]

My fridge performed poorly on propane. I cleaned the burner. No fix. I cleaned the chimney. No fix. I studied up on propane gas pressure and learned mine was too low. I adjusted the regulator. My fridge cools like it should.

[graysailor]

I have a new 2016 Classic and had the same problem. Took it back to the dealer and he said the control board was bad. He has replaced the board and said it works fine. I have not as yet had a chance to verify the repairs.

[JCWDCW]

What you see is external rust from exposure to heat as noted above. That in itself is not likely the problem. Since you have the chimney out blow it out good with air and see what comes out. If there is a lot of rust and particles that may be the problem...or not!
You can have the unit refurbished for about half the cost of new, and since you have it out of the trailer you can deliver it to the RV service co. and save some labor. They will either refurb your existing refrigeration system or if they have a rebuilt on hand they will exchange it out and do all the necessary heat transfer putty etc, ready for you to put it back in. My cost was $800 here in Ontario about 4 years ago.
But! since your unit runs well on Electric, then it is likely a plugged chimney, not an issue with the ammonia/hydrogen charge. Again that is a simple fix by a service tech which will still be a lot cheaper than replacement. never heard of anyone actually opening up the chimney and doing it themselves, but it must be possible.
JCW

[Jacob D]

My vintage Dometic started cooling insufficiently on gas after many years of service even though I clean the flue pipe twice a year. I removed the gas nozzle, soaked it overnight in denatured alcohol, blew thru it with compressed air and replaced. Has worked fine now for two years (knock wood). I hold my breath every time I turn it on considering it is now 49 years old.

[alantbird]

When the heat is proper you can hear the liquid boiling. When the flame is right the tip should suck up inside the flu pipe and if your temp valve and filter are in working order the flame should back off slightly at lowest temp setting

[ijustlee]

Gas refrigerators usually cool better on gas than electric because the flame heats the liquid inside the boiler better. When working properly the boiler section sounds like a coffee percolator. You must not be getting a enough heat from the flame or not enough cooling airflow out the roof vent for it to be working like this. The gas thermostat just reduces the flame a little when the box is cold enough but the electric thermostat turns off the electric heating element completely when the box is cold enough. The difference in the flame is noticeable when things are working right so you should make yourself familiar with what things look like when working right. You probably just need to clean the burner and flue to fix this, sometimes cobwebs or bugs block the gas or airflow while the trailer sits. At worst you might need a thermostat.

[jami20]

Thanks you all for the replies. I'm going to try to take the burner off and soak it to see if that may be the problem. From what everyone is writing I'm thinking that maybe the flame needs to be a little more intense than I'm seeing. I definitely don't hear any sound like coffee being brewed.

[TG Twinkie]

The boiler in my refer is silent. When the various tubes get warm/hot it is working.
Don't poke anything in the burner orifice you will damage it. Use compressed air.

[BigAl]

in mine the burner orifice is actually a ruby with a small hole in it. they are fragile as mentioned above. Just soak in alcohol and blow out.
Since the original poster has his unit out he can remove the baffle which is inside the chimney. Should come out the top. Then it is easy to clean out the chimney. A long bottle brush works well.
Al

[jami20]

I wanted to follow up with my original post. I took the recommendations of everyone here and my fridge is now working

Here's everything I did:
1. Turn off the propane!

2. I cleaned out the flue when I took the fridge out. While I'm sure that was helpful, it didn't solve any problems. (In fact since I still had the burner tube screwed in place it probably would have caused problems if they didn't already exist. So, if you do this be sure to take off the burner tube either before or after cleaning the stack.)

The next two things I did at the same time so I'm not sure which one of them was more beneficial. Although I suspect both of them were at least somewhat needed.

3. I unscrewed the brass burner orifice that is connected at the end of where the LP line screws in (kind of under and to the right of the solenoid) and then soaked it in denatured alcohol for about 45 minutes (probably much longer than needed, but I left it soaking while I did other things). I let the orifice air dry and then gently blew compressed air in it, careful not to touch the small pin sized hole. As people have noted, you don't want to mess with that hole at all.) I then screwed it back into place.

4. I took off the burner tube and "cleaned" it out next. I would have also soaked it in alcohol but didn't have the alcohol with me then so I skipped that step. All I
did for this "cleaning" was tilt it over (after unscrewing it) and watch a lot of very fine black dust fall into my hand. Then I used the compressed air to blow all through it. Then I reinstalled the burner. Note to get the burner out if your fridge is like mine then you will have to first unscrew the large flat outer plate of metal (that has electrical schematics on it - 4 screws), then you unscrew the cover plate that goes over the burner and ignitor (1 screw - have to work to get it off), next you take off one more screw that holds the metal piece in place that the burner tube is connected to.

After reconnecting everything I fired the fridge up and immediately noticed that the flames were all blue coming out of the burner tube. Before they had been more of an orange and yellow color. I also noticed the sound that was mentioned here as sounding kind of like a coffee pot. I stuck a half bottle of water in the freezer and came back three hours later to see ice in the bottle!

So, if you are having problems with your fridge not working on propane then take the above steps (really 3 & 4 first). The whole process, minus the soaking, probably took me 10-15 minutes.

Here is a great site that offers directions similar to what I've written here (but better). http://www.rverscorner.com/articles/refer.html

Maybe if I get time I'll do it all again and take a video this time to post on youtube.

[graysailor]

I did in fact have the control board replaced and that solved the problem. Now it works fine on propane. Before replacing the board it did work on AC.

[JCWDCW]

Jami20 Quote <After reconnecting everything I fired the fridge up and immediately noticed that the flames were all blue coming out of the burner tube. Before they had been more of an orange and yellow color. I also noticed the sound that was mentioned here as sounding kind of like a coffee pot. I stuck a half bottle of water in the freezer and came back three hours later to see ice in the bottle!> Quote

I would say the burner tube was the problem all along. You were getting a flame...poor one but a flame none-the-less. I have had to clean the burner on my '89 several times. Dirt and rust drop onto the slotted burner and clog it. Tube was nearly full first time I pulled it out. Congrats...you pulled the whole fridge...not many of us are quite that adventure-some.
JCW

[jami20]

Yeah, I don't know if I would haven taken the fridge out if I had not needed to do so in order to run wiring for the solar. I did it by myself and would not advise anyone to do that. It's not light and it would have been extremely helpful to have had a helper.

I also should say that it only took about 15 minutes to do, not including removing the fridge.

[Ripley345]

Hello Everyone... My refrigerator pilot comes on and I can feel it heating the plate. and sensors on front know if AC is plugged in or if it is trying to cool with gas. BUT it never gets cool.

How do I check if I have refrigerant?

Does anyone have instructions as to how to replace the compressor?

Does anyone have the steps to pull the fridge?

I am guessing it is not just my flame, but another issue since not working on either source.

Thanks

Ren

[TG Twinkie]

There is no compressor in your refer. There is no refrigerant.
RV refers use and ammonia based system which is enclosed and heated with a burner (no pilot) or a electric heating element if on shore power.
If you don't see any yellow dust or smell ammonia the system may be OK.
There are a number of things that could cause problems. You may be able to find a PDF file (manual) on your specific model to help you analyze the problem(s).
It could be as simple as bad connection(s) on the control board.
Are you sure you have 12 volts DC at the refer?

[Silver Otter]

Yep, the dreaded yellow dust signaled the end of our Dometic from 1999. Replaced with a NorCold and very very happy.