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RVing message boards => Tech Talk => Topic started by: Digger89L on September 17, 2017, 09:44:38 PM

Title: Dometic RM660 fridge problems
Post by: Digger89L on September 17, 2017, 09:44:38 PM
I'm new to the forum, and new to RV'ing. My wife and I bought a vintage 1979 Dodge Diplomat 23 foot class C vehicle a few months ago  ...with only 40,000 miles on it!!  It's a real time capsule, well maintained and runs just fine. Everything is original, including the Dometic RM660 three-way fridge. I've been struggling trying to get the fridge up and running. I've done all the suggested things: cleaned the burner (its working fine now ...nice blue flame); checked all the electrical stuff, etc., etc.; even removed the fridge and 'burped' it a few times (even though the 'experts' say that makes no difference). I could hear the refrigerant gurgling through the pipes. Here's the present status: on 12v and 120v the heater warms up, but doesn't seem to get hot enough to circulate the refrigerant. (again, the 'experts' say the 12v and 120v heaters are a 'no work' or 'work' situation  ...either get hot, or don't even get warm, so 'getting warm' puzzles me). The propane heater works much better: seems to be circulating the refrigerant nicely; can hear it gurgling thru the pipes, and the tubes at the back (bottom part that I can reach) get hot enough that I can't leave my hand on them for more than 20 sec or so. However, the fridge does not get cool inside  ...its actually about 10 degrees warmer than the temp outside the fridge. I've left it running on propane for more than 12 hours cooling. So ....not sure what to do next?  Getting the current fridge repaired at a professional shop, or replacing it with a new one are 'options of last resort' as either would likely double the value of the old RV !!  One option I'm seriously considering is replacing it with a small 120v 'bar fridge' (1.7 or 2.2 or 3.3 cu ft) that could possible be operated off an inverter so I can use it while the RV is moving.  Any helpful comments or suggestions are welcome.
Title: Re: Dometic RM660 fridge problems
Post by: Gary RV_Wizard on September 18, 2017, 08:26:44 AM
Hearing gurgling is not a good sign - an absorption fridge is normally completely silent in operation.

You can get a service manual for it at but I think that "bar fridge" is going to be your answer.
Title: Re: Dometic RM660 fridge problems
Post by: Digger89L on September 18, 2017, 12:37:23 PM
Well, that's interesting. Other research I've done says gurgling is a good thing: indicates the refrigerant is 'there' ...and that it's boiling and circulating. I've seen no evidence of an ammonia leak smell, no residue, etc.
I've already downloaded that service manual (the RV actually came with the fridge owner manual, and it has much the same info, only less detailed, as the service manual. Neither has a numbered parts list, though. Curious) and it is very, very general when it comes to diagnosing problems.
The fridge sat unused for 5 or 6 years, so perhaps that's part of the problem. Maybe the ammonia leaked out quite a while back, and the smell has disappaited. Any advice on 'waking up' a dormant fridge?  Would pressure test tell me anything?