Dometic Fridge RM 211 heating element replacement - anyone else need one?

[Lizbun]

Is anyone else interested in a new element for their Dometic RM 211 fridge? Part no. 2901943-000MC

Our little camper fridge runs fine on propane but my husband won't be happy until it runs on electricity again too. Honestly I would rather keep the old fridge running and not have to retrofit a newer model fridge, which is a fair bit deeper and won't fit as well...

I definitely can't find available catalogue parts for it anywhere, so I've contacted an industrial manufacturer with the element specs to request a quote for making one.

I'd be willing to order a couple extra if they're not too expensive, help some other fellow FiberglassRV comrades out. I know there's a couple posts on here with people trying to find that part.

[Phil 4500]

Hi, I’d be interested in getting one as a spare but we took our fridge to a Rv fridge specialist in New Brunswick last year called Dads Marine and RV Refrigeration. He also could not get the original part but with his expertise and experience he was able to modify a similar part to fit.

[Lizbun]

Yes I've seen their site... maybe I should contact them if you got one from them...

Being in Alberta there's a ton of specialty fab shops, I figured they should be able to help me out, already got someone working on it.

Will pm you to ask for the details of your order so I can reference that work to the east coast company.

[Camper Brent]

Hi Lizbun,

We have the same issue on the same fridge. Works on propane but not electricity. (Also in Alberta!) Any luck with acquiring this part?
Q: how did you diagnose the problem to the element?

Many thanks!
-Brent

[David Tilston]

Originally Posted by Camper Brent

Hi Lizbun,

We have the same issue on the same fridge. Works on propane but not electricity. (Also in Alberta!) Any luck with acquiring this part?
Q: how did you diagnose the problem to the element?

Many thanks!
-Brent

Brent, Check the resistance of the 120 VAC, and the 12 VDC connections to the heater. Below is a cut from the RM211 manual:
Electrical.JPG Views: 2 Size: 34.1 KB ID: 140314" style="margin: 2px" />

https://www.fiberglassrv.com/forums/...FrigManual.pdf
In the upper right of the wiring diagram are the heaters. The manual says that the heaters are 95W.
Power = Voltage x Current
Power/Voltage=Current
95W/110V=0.86Amps

Voltage/Resistance=Current
Voltage/Current=Resistance
110V/0.86A=128 Ohms

So, from the black wire to the red wire, there should be about 128 Ohms.

The process above can be shortened by replacing Current in the first power formula with V/R or P=V²/R this is rearainged to solve for Resistance:
R=V²/P
R=12²/95
R=144/95
R=1.52 ohms

So, from the brown wire to the black wire, there should be about 1.5 ohms.

Below is a picture of where this terminal strip can be found:

[Camper Brent]

Thanks David!

Your an incredible resource! I appreciate your time, and knowledge.
This info should come in handy in the very near future to help me trouble shoot the electrical situation, hopefully make the repairs needed, and be up and running shorly there after.

Wish me luck! And thanks again!!
Stay positive Fiberglass RV community!

[thrifty bill]

One other thing to look at is the 120V pigtail itself. On my camper, it was badly degraded, exposed wire. Most of this pigtail is not visible from the lower outer fridge hatch.

In my pictures, you can see how the insulating jacket on the wire had failed. In my case, after replacing this pigtail, fridge works fine on 120V. I did the test that Dave refers to above.

[David Tilston]

Originally Posted by thrifty bill

One other thing to look at is the 120V pigtail itself. On my camper, it was badly degraded, exposed wire. Most of this pigtail is not visible from the lower outer fridge hatch.

In my pictures, you can see how the insulating jacket on the wire had failed. In my case, after replacing this pigtail, fridge works fine on 120V. I did the test that Dave refers to above.

Just curious, did you get something close to 128 ohms?

[gordon2]

Originally Posted by Camper Brent

..
Q: how did you diagnose the problem to the element?

..

Google is my friend... http://www.bdub.net/manuals/DometicBulletin12-87.pdf

[thrifty bill]

Originally Posted by David Tilston

Just curious, did you get something close to 128 ohms?

Yes I don’t recall exact reading but it was close.

[Borden]

Great help well done learned as well Thanks!

[David Tilston]

One day, I will pull the heater on one of my fridges, (when it breaks) and construct a new heater element. This is not rocket surgery. If you google, “Heating Element Wire” Cr25Ni20, (similar to Austenitic stainless steel) seems to be an available alloy for this purpose. Cr25Al5 is also fairly common, but I am reluctant to use aluminum. Coil it up in a length that meets the resistance numbers generated previously, and a diameter that is slightly smaller than the existing element. I would probably use a larger gauge of wire on the 12VDC side, (more current). Then encase it in some heat resistant grout. There is more to it thant this, (like attaching the copper lead wires) but doable.