Running out of ideas for my 3-way Dometic not cooling on propane

simonsl23

New Member
Feb 15, 2017
5
I know there are several posts about this topic but I haven't found one that has helped me fix my fridge. It is a tale as old as time...the fridge works fine on 12V and 120V but not on propane. I was able to get the inside down to 34°F (outside at 72°F, delta -38°F) on A/C but the best on can do on propane is 51°F when the external was 65°F (delta of -15°F). Both of these are with my 2 fan mod and baffles in place and running. I checked the burner and it looked fine but I blew it out with compressed air anyway. The flame is completely blue and looks fine to my inexperienced eye (see photo). I also removed the flue baffle (see photo) and scrubbed the inside of the chimney with a nylon brush (nothing of note came out the bottom or with the brush). I have a feeling that it is heat transfer inside the chimney or ineffective heat removal from the vent even with the fans running. Is there anything else I can do to troubleshoot this further to find the problem?





bottom baffle.jpg fans.jpg top baffle.jpg burner.jpg flue.jpg
 

Dave2514g

Active Member
Sep 2, 2019
223
Ontario, Canada
If you have a good flame and good air circulation you may have lost some refrigerant; or the refrigerant may not be moving freely thru the lines.

RV fridges use ammonia as a refrigerant; if you have a bad leak it will show up as yellow stains. If you don't see, smell or hear gurgling when running the fridge you hopefully have no leak.

The next thing to do would be to remove the fridge from the trailer and burp it. Try a Google or YouTube search for burping an RV fridge for details.
 

SteveP

Super Active Member
Platinum Supporting Member
May 21, 2015
2,550
Hard to tell but in your 3'rd pic it looks like the baffle is covering the top of the chimney. If so cut the baffle around the chimney so that you get better air flow through the heater.
 

NLB

Active Member
Silver Supporting Member
Oct 10, 2021
476
West Palm Beach, Florida
Appreciate the pictures. Looks to me that the top or the chimney needs to be rotated a few degrees clockwise. It appears to be slightly directed to the very right of the vent.
Also, tell me about the fans. Are they blowing up or down?
Usually they are mounted inside the upper vent exhausting the hot air and drawing cooler air in thru the lower vent.
(Maybe I’m just not seeing the pictures properly).
 

simonsl23

New Member
Feb 15, 2017
5
Hard to tell but in your 3'rd pic it looks like the baffle is covering the top of the chimney. If so cut the baffle around the chimney so that you get better air flow through the heater.
The chimney T is over the baffle. It is pointed directly toward the exhaust vent.

chimney vent.jpg
Appreciate the pictures. Looks to me that the top or the chimney needs to be rotated a few degrees clockwise. It appears to be slightly directed to the very right of the vent.
Also, tell me about the fans. Are they blowing up or down?
Usually they are mounted inside the upper vent exhausting the hot air and drawing cooler air in thru the lower vent.
(Maybe I’m just not seeing the pictures properly).

The fans are in the upper vent blowing up on the fins of the radiator. They are located directly behind the top baffle. They move air from the bottom vent out the top vent. I don't think air movement is the issue but if there is a better way I'd be happy to hear about it.
 
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NLB

Active Member
Silver Supporting Member
Oct 10, 2021
476
West Palm Beach, Florida
You have done a nice job on the baffle. I would only suggest two things.
1. Mount the fans directly to the inside of the upper vent, blowing out.
2. Seal the top and upper sides of the box with HVAC silver tape so that the heated air isn’t just flowing around in there.
I’ve done both with my 2006 vintage 2193 and believe it helped. I’m of the opinion that the insulation of the box and around the box deteriorated over time.
The other mod that I think has helped is cutting Reflectix to completely cover the inside of the unit, including a piece on the inside of the door and the bottom. When I break camp, I remove the bottom piece and the lower side pieces, dry the cabinet, leave a towel to catch any condensation, and leave the door partially ajar to prevent mold.
Like you, I have much better temp with 110 than gas. The PO told me it was like that since the PUP was new. He never improved the baffling or added fans…he just lived with it.
One other thing…I fabricated a Reflectix shield outside to keep direct sun off the vent areas. Simple affair, attached with a tool bar magnet above the vents, and supported with a couple fiberglass marker stakes at the outer edges.
Happy Trails!
 

bupkis

Howdy!
Mar 3, 2006
7,902
N. TX
heat, level and ventilation.
how much heat are you getting from propane?
apparently you get enough from 12 or 120v
 

xxxapache

Super Active Member
Jul 30, 2008
4,453
You cannot judge propane pressure by looking at the flame. You need to test your pressure with a manometer.
 

Grandpa Don

Super Active Member
Sep 5, 2018
1,705
Southern California
If you have a good flame and good air circulation you may have lost some refrigerant; or the refrigerant may not be moving freely thru the lines.

RV fridges use ammonia as a refrigerant; if you have a bad leak it will show up as yellow stains. If you don't see, smell or hear gurgling when running the fridge you hopefully have no leak.

The next thing to do would be to remove the fridge from the trailer and burp it. Try a Google or YouTube search for burping an RV fridge for details.
But he said that it works fine on AC and 12 Volts DC. That tells me that the system is fine and that it is isolated to Propane.
 

Everett Bartlett

Active Member
Aug 2, 2020
175
Southern Nevada
Have you cleaned the burner orifice???? Take the burner assembly off, be careful of the flame sensor tube, Donot use any metal to probe the orifice. Take and put the burner assembly in a ultrasonic bath of 90 % Isopropal alcohol, and let run for 15 min. That will desolve any spider web material in the orifice. You can use the cheep ultrasonic Jewelry cleaner for this.
Check the gas pressure with a maometer. You should be able to have a rv dealer to check that.
 

Grandpa Don

Super Active Member
Sep 5, 2018
1,705
Southern California
When my cousin removed his 3-way and replaced it with a brand new one, he sent me some of the parts that he thought I may need in the future. One of the items was the little orifice. I visually inspected the little hole. It looked fine to my naked eye. But then I used a magnifying glass to have a closer look. Sure enough, there was a slight obstruction in the hole. It almost looked like the hole was not punched properly at the factory. The only way I could clear it was with a very tiny metal bristle from a golf club head cleaning brush. It was the only thing I could fine that was small enough to enter but not accidentally enlarge the hole. Then while we were on our last camping trip, his brand new Fridge just didn't seem to be getting as cold as we thought a brand new one should. So I removed the orifice on it and found that it had the same little obstruction as the one he sent to me. And that Fridge was brand new.

We were using my Alpicool for perishable, but decided to experiment with his Fridge. I had a very small sewing needle in my First Aid kit and tried to clear it out with that. I didn't put the needle all the way in the hole, but still I accidentally made it larger. But not by a noticable amount. After reinstalling the orifice in the Fridge you could actually hear the flame burning. It was a little scary, but we decided to let it go and see how it does. We had a fire extinguisher close at hand and never left camp while it was lit. Sure enough the inside temperature dropped considerably as the afternoon progressed. He said he would replace the orifice with a proper one as soon as we get back home. But I thought it was an interesting experiment.
 

Dave2514g

Active Member
Sep 2, 2019
223
Ontario, Canada
But he said that it works fine on AC and 12 Volts DC. That tells me that the system is fine and that it is isolated to Propane.
You're absolutely right, thanks for pointing that out. My apologies for looking at this as a whole fridge problem. I totally missed the line where he said it works fine on electric and glossed over the temps given as Fahrenheit isn't familiar to me.

Lots of great advice on here already, but checking gas pressure and cleaning the orifice on the jet would be my first steps.

Unlikely you have a nanometer, so start with cleaning the jet. I've had good luck letting it soak in brake clean overnight then blowing it out with compressed air.

Around here, my fridge issues are that it always freezes everything up even on low settings. We did have daytime highs of 35 (95F) the last trip and I finally had to turn up that dial ;)
 

Grandpa Don

Super Active Member
Sep 5, 2018
1,705
Southern California
You're absolutely right, thanks for pointing that out. My apologies for looking at this as a whole fridge problem. I totally missed the line where he said it works fine on electric and glossed over the temps given as Fahrenheit isn't familiar to me.

Lots of great advice on here already, but checking gas pressure and cleaning the orifice on the jet would be my first steps.

Unlikely you have a nanometer, so start with cleaning the jet. I've had good luck letting it soak in brake clean overnight then blowing it out with compressed air.

Around here, my fridge issues are that it always freezes everything up even on low settings. We did have daytime highs of 35 (95F) the last trip and I finally had to turn up that dial ;)
I sometimes do the same thing. I will just quickly read a post and don't really comprehend what it is saying. I did that on one of your posts. Remember? Sometimes there are so many posts in the same thread that you just don't want to take the time to go back and read every one again. Or do a search on the whole Forum. Most of us long time posters know that.
 

Oldspurs

Active Member
Jan 2, 2022
178
Central Texas
When my cousin removed his 3-way and replaced it with a brand new one, he sent me some of the parts that he thought I may need in the future. One of the items was the little orifice. I visually inspected the little hole. It looked fine to my naked eye. But then I used a magnifying glass to have a closer look. Sure enough, there was a slight obstruction in the hole. It almost looked like the hole was not punched properly at the factory. The only way I could clear it was with a very tiny metal bristle from a golf club head cleaning brush. It was the only thing I could fine that was small enough to enter but not accidentally enlarge the hole. Then while we were on our last camping trip, his brand new Fridge just didn't seem to be getting as cold as we thought a brand new one should. So I removed the orifice on it and found that it had the same little obstruction as the one he sent to me. And that Fridge was brand new.

We were using my Alpicool for perishable, but decided to experiment with his Fridge. I had a very small sewing needle in my First Aid kit and tried to clear it out with that. I didn't put the needle all the way in the hole, but still I accidentally made it larger. But not by a noticable amount. After reinstalling the orifice in the Fridge you could actually hear the flame burning. It was a little scary, but we decided to let it go and see how it does. We had a fire extinguisher close at hand and never left camp while it was lit. Sure enough the inside temperature dropped considerably as the afternoon progressed. He said he would replace the orifice with a proper one as soon as we get back home. But I thought it was an interesting experiment.
Good experiment. Don you might look at buying a torch cleaning kit to place in your emergency repair kit. Small blue Ally Tools cleaning kit from Amazon is about $ 8.00 US. I keep one in my tool kit, and have for years, for cleaning orfice tubes, cutting torch tips, touch holes, and cap nipples in black powder hunting rifles. Also has a metal emory file. See you on the trail.
 

Grandpa Don

Super Active Member
Sep 5, 2018
1,705
Southern California
Good experiment. Don you might look at buying a torch cleaning kit to place in your emergency repair kit. Small blue Ally Tools cleaning kit from Amazon is about $ 8.00 US. I keep one in my tool kit, and have for years, for cleaning orfice tubes, cutting torch tips, touch holes, and cap nipples in black powder hunting rifles. Also has a metal emory file. See you on the trail.
I tried to find one of those kits the other day when I went to Home Depot and Harbor Freight, but nobody had one. That is one tiny hole. Are you sure that kit would have one small enough?

Bye the way, I'm still experimenting with my 3-Way. I'm running it on AC right now just as a test. I turned it on at 7 this morning. It is 98 degrees (F) outside right now and the inside is 46 degree. I went out to check on it a minute ago, and found out that I had a loose connection in my fan wiring. The Fans weren't running at all. I got them working again, but I have to find that loose wire and fix it permanently.

And I ordered a new Propane regulator this morning. I don't know that mine is not putting out the correct volume, but they are not very expensive and are easy to change. And one more thing. I turned the "T" exhaust pipe away from the cooling fins and made a small box affair to help direct the hot are directly out of the vent. I also moved the 3rd fan over to help move the air out faster. Let's see how that does.

I wish I could think of a way to get cooler air from the outside to go into the bottom. According to my infrared thermometer, the air going in at the bottom is 100F, equal to the outside temperature. If there was a way to make that air cooler, it might help cool down the fins better. The only way I can think of right now is to wait for winter.
 
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xxxapache

Super Active Member
Jul 30, 2008
4,453
It's a shame that all RVs don't have a built in manometer gauge, so you could tell that your regulator is working correctly with a glance. I bet that would probably cost the manufacturers a whole ten bucks, though.

20220731_161812.jpg
 

Oldspurs

Active Member
Jan 2, 2022
178
Central Texas
I tried to find one of those kits the other day when I went to Home Depot and Harbor Freight, but nobody had one. That is one tiny hole. Are you sure that kit would have one small enough?

Bye the way, I'm still experimenting with my 3-Way. I'm running it on AC right now just as a test. I turned it on at 7 this morning. It is 98 degrees (F) outside right now and the inside is 46 degree. I went out to check on it a minute ago, and found out that I had a loose connection in my fan wiring. The Fans weren't running at all. I got them working again, but I have to find that loose wire and fix it permanently.

And I ordered a new Propane regulator this morning. I don't know that mine is not putting out the correct volume, but they are not very expensive and are easy to change. And one more thing. I turned the "T" exhaust pipe away from the cooling fins and made a small box affair to help direct the hot are directly out of the vent. I also moved the 3rd fan over to help move the air out faster. Let's see how that does.

I wish I could think of a way to get cooler air from the outside to go into the bottom. According to my infrared thermometer, the air going in at the bottom is 100F, equal to the outside temperature. If there was a way to make that air cooler, it might help cool down the fins better. The only way I can think of right now is to wait for winter.
Yes, Sir, it goes down to a fine wire. Wires also have abrasive side on the tips. I have one on my welding trailer, it has the 5" cleaners. However the one I keep in my emergency kit as 3.5" wires 13 of them.
 

simonsl23

New Member
Feb 15, 2017
5
I took apart the burner and cleaned out the orifice (which appeared to be clean) and burner assembly. The burner definitely had some black corrosion that came out with a small bottle brush and compressed air. After reassembly and testing the fridge is cooling quite nicely (36F internal, 79F external for a delta of -43F). Visually to my eye I see no real difference in the flame but clearly it must be producing more heat. We are spending a week at a rustic campground starting next Sunday and it will be very nice to have a working fridge.

Thank you all for the help. I really appreciate you all taking the time to troubleshoot this with me.
 

Grandpa Don

Super Active Member
Sep 5, 2018
1,705
Southern California
I took apart the burner and cleaned out the orifice (which appeared to be clean) and burner assembly. The burner definitely had some black corrosion that came out with a small bottle brush and compressed air. After reassembly and testing the fridge is cooling quite nicely (36F internal, 79F external for a delta of -43F). Visually to my eye I see no real difference in the flame but clearly it must be producing more heat. We are spending a week at a rustic campground starting next Sunday and it will be very nice to have a working fridge.

Thank you all for the help. I really appreciate you all taking the time to troubleshoot this with me.
That 43 degree split is about what I get, even with all of my mods. It seems to be fairly normal for these Fridges. Last week I ran a test on Shore Power with the outside temp at around 100 degrees (F). The best the Fridge could do was down to about 48 to 50. I think if I had the Fridge full of stuff it might stay a little lower as the outside temp went up. Changing over to Propane made no difference. Still the same split.
 




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