New Fridge not cooling adeqautely

Riwright · 08-27-2014, 01:54 AM

I have a brand new Dometic RM2354 Americana refrigerator that I had a dealer install to replace a Norcold that burned.

The frig is not performing well. The frig will maintain about 20 degrees colder than the outside at best. The low 50's is the lowest I've seen. During the day it's in the 60's. Outside temps are low 80's during the day and 50-60 at night. I have run it only on propane. The freezer gets a little below freezing. The controls are set for maximum cooling. I have a wireless thermometer for both the freezer and the frig compartment.

I have run the frig through 2 camping trips completely empty so hot food is not a factor. The trips were 3-4 days long so it has plenty of time to start working.

The last trip I removed the top vent cover and put in a couple of computer fans to improve airflow. This seemed to help just a bit but it didn't fix it.

The burner shows a blue flame with a little bit of yellow. The tube at the top of the boiler is hot, 200-300 degrees. The cooling fins cool it down to 85 or so. One thing I am not sure about is what the size of the flame is supposed to be.

There aren't a lot of parts to this thing. I'm sort of running out of things to check.

I plan to take it back to the dealer but it will be a month or so before I can take it down there again. It would be nice to get it working.

TrailManorMan · 08-27-2014, 05:14 AM

Try loading it with pre-cooled items such as water or cans of drinks. an empty refrig will not cool as well as a full frig. might make a difference.

08-27-2014, 05:22 AM

You don't want any yellow in the flame. That is incomplete combustion, causing soot. Adjust the air damper to get a clean blue flame.

Padgett · 08-27-2014, 06:45 AM

Adding fans is a real good idea since cooling the fins is critical but the fact is that any gas absorption cooling is just not very efficient, is best for keepig cold things cold rather than actual cooling. To really cool things needs a compressor.

"In the early years of the twentieth century, the vapor absorption cycle using water-ammonia systems was popular and widely used, but after the development of the vapor compression cycle it lost much of its importance because of its low coefficient of performance (about one fifth of that of the vapor compression cycle). Nowadays, the vapor absorption cycle is used only where waste heat is available or where heat is derived from solar collectors. Absorption refrigerators are a popular alternative to regular compressor refrigerators where electricity is unreliable, costly, or unavailable, where noise from the compressor is problematic, or where surplus heat is available (e.g., from turbine exhausts or industrial processes, or from solar plants" http://en.wikipedia.org/wiki/Absorption_refrigerator

tentcamper · 08-27-2014, 08:52 AM

Have you run it on 120V AC? if not try it in the drive and see what temp you get after 24 hours? If it cools down to 50+ below outside temp with AC then the issue would be with the propane control or burner. If it does not and you get the same temps, I would think the fridge cooling system is the issue.

What type of warranty do you have on the new fridge? I would take it back to the dealer and have them figure it out if it's covered?

Years ago, there was a thread I read on another form that someone had an issue with a new domitic fridge and in both AC and propane mode not getting a good temp drop. He described the same type of issue. A month or so latter It sounded like he found that the aluminum cooling plat inside the fridge was not making good contact with the coolant tubes. There was some interference caused by the plastic, which he trimmed off the access plastic and all was well.

ThePair · 08-27-2014, 08:53 AM

Are your fans venting in or out? For the record, they need to vent out. The fridge relies on convection, and you are trying to improve the flow of air in the bottom vent and out the top vent.

Full fridge works better and stays colder than empty fridge.

Getting some kind of fan for inside the fridge will help as well. I've got two PC fans blowing into the fins below the freezer inside, and two PC fans mounted to the top vent blowing out. Definitely helps. Try to keep direct sun off that side of the TM also helps.

I don't use propane so I don't have much more to add...

scrubjaysnest · 08-28-2014, 08:31 AM

The Dometics usually have a thermistor sensor on the cooling fins unless yours doesn't have electronic control. The thermistor is moved up or down to adjust temp. If I remember correctly move it up for colder.

Riwright · 08-28-2014, 12:01 PM

Thanks for the suggestions folks.

I don't have power on the lot where I store the TM. I think I'll chain the generator to the bumper and let the frig run on AC for a while. Hopefully the gasoline will last long enough for a good test.

My current working theory is that that the propane pressure in the trailer is too low and that not enough propane is getting into the burner. I don't have a way to test the pressure though. Maybe I should get one of those pressure test kits.

If it runs fine on AC then that supports my theory.

I looked at the flame at night. It looks "OK". Hard to tell if it's too small or too large. Looks a little weak to me but I have no reference. Also on this model you can't see the entire flame, it goes up into the pipe.

I could try running it on DC but that's got some problems. My calculations show that at 12A my 220AH batteries will give me about 9 hours before they become more than 50% discharged. I don't want to run them down any further than that. I also don't think that the DC heating element puts out as much heat as the AC element.

tentcamper · 08-28-2014, 12:32 PM

You can make a meter with about 6+ feet of clear tubing a board, water, ruler and a fitting that fits on the test port and tube. Food coloring can be added to the water to see it better.

All you need to do is fix a clear tube on a board in a U shape that each side of the U is about 26" long and one end of the tube it long enough to reach the propane test point. Add water to the tube until each side of the tube has about 12" of water from the bottom of the tube. Standing the board straight up and with the propane turned off, Put the fitting in the test port of the control valve and connect you tubing. Mark where the water level is on the side furthers from the control valve. Turn on the propane and measure how many inches the water rises. It should be around 11" if it is not make adjustments as needed to get as close as you can to 11".

08-28-2014, 04:14 PM

Code:

Turn on the propane and measure how many inches the water rises. It should be around 11" if it is not make adjustments as needed to get as close as you can to 11".

It should be a total difference of 11" between the two sides of the loop or a rise of 5 1/2 " in the open end tube.

Ed