Dometic rm2652

[Josh_IL]

Hey all, new here and need help!  Fridge worked fine for months in the driveway, and previous trips this year, last weekend it stopped working and kept tripping the limit on the flue. I do not know a ton about these fridges, but have been a refrigeration tech for 18 years, so this is embarrassing!  Yes its level, tried ac power and lp, ac heater works, lp ignites, then trips the limit. After reading this and other forums, I will say that there is no yellow staining, but coil does not get hot either. I'm leaning towards replacement, but dont want to if I dont have to!  Any help is greatly appreciated!!  Thanks

 

[Josh_IL]

There is an axial fan outside that is switched by a thermal switch on the coil. I jumped it out and it does work, but after 30 plus minutes, the coil didnt heat up enough to cycle it on by itself. Anybody know what temp that switch makes at?

 

[Josh_IL]

I'm grasping at straws at this point because we were going to trade it in this fall and I dont want to have to replace the cooling unit before I do!

 

[regval]

Here's a link to the service manual.
https://fourwheelcampers.com/NewDometicRefrigeratorManual.pdf
There are many internet articles on how absorption refrigerators work so no need to repeat it here.
The thermofuse located on the boiler is normally resettable and it locks out the heat source by shutting down the LP or electrical heating when the boiler temperature is too high. Generally if the thermofuse continually trips it means there is likely a blockage in the cooling unit tubes and the liquid cannot return to the boiler and the cooling unit has failed.

 

[Alfa38User]

You do realize that 30 minutes to cool on these fridges is nothing. It will take quite a few hours to cool noticeably. If that Thermafuse you speak of was installed as part of the Dometic recall a few years ago, contact Dometic, it may be replaceable for free by a Dometic approved repair person.

 

[Gary RV_Wizard]

If the cooling unit is working, the boiler area and vertical flue should be hot, too hot to touch, but the rest of the tubing coming back down from the top should only be be warm. If the thermafuse (a Dometic term) on the flue & perc tube is tripping, that area is probably approaching 800 F.. If the thermafuse is working properly, that's a sure sign of a failed cooling unit. There are two possible causes, neither of which is repairable: (1) a pinhole leak in the cooling unit has let the hydrogen gas escape, or (2) the passages inside are clogged with sodium chromate sediment (meaning it has been operated off-level in the past).

Note that I said " If the thermafuse is working properly".  They have been known to give inaccurate results. Norcold has had numerous problems with their boiler high limit sensor, but Dometic not so much.

Only a modest percentage of cooling unit failures show the "yellow powder" symptom. Lack of a yellow stain doesn't prove anything.