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Old 06-29-2012, 04:13 PM   #1
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Dometic fridge repair

Hi All,
I have an RM3804 which needs a power board and a cooling unit. I've looked into after market boards which run about $150 and a rebuilt cooling unit which runs $400. This is still WAY cheaper than replacing the fridge (it's from a '91 Excella.) Has anyone on the Forum had any luck with trying to fix the Dometics? Particularly, has anyone used a rebuilt cooling unit?
Thanks,
Laura
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Old 06-29-2012, 04:27 PM   #2
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Same problem. I went new for a bunch of $$$. I was quoted $500 for a new cooling unit and $400 labor to repair and I still had an old fridge so I went new.
I would be leery of a "rebuilt" cooling unit. The cooling unit wears out when the heat wears a hole in it and the ammonia leaks out. Rebuilt probably means soldering up the hole and that is not a very good fix. Ammonia vapors are hazardous and nothing to mess with.
My fridge wore out in a 2004 Safari. You are lucky yours lasted as long as it did.
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Old 06-29-2012, 04:58 PM   #3
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If the control board is bad how do you know the cooling unit is bad?

Perry
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Old 06-30-2012, 01:24 PM   #4
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Dometic fridge

Perry,
I "hot wired" the heating element, so that I could by-pass the board. It heated up, but never cooled, so I'm assuming there's either zero ammonia or too little to make it work. It doesn't have any ammonia stains or odor. It had been sitting up with the previous owner for 2 years, so I suppose the lines could be clogged.
L
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Old 06-30-2012, 02:11 PM   #5
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Old cures sometimes work

Quote:
Originally Posted by roadtrip2 View Post
so I suppose the lines could be clogged.
Did you try "burping" the refer? Doesn't cost anything, it has been rumoured to work...
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Old 06-30-2012, 02:22 PM   #6
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Quote:
Originally Posted by roadtrip2 View Post
Perry,
I "hot wired" the heating element, so that I could by-pass the board. It heated up, but never cooled, so I'm assuming there's either zero ammonia or too little to make it work. It doesn't have any ammonia stains or odor. It had been sitting up with the previous owner for 2 years, so I suppose the lines could be clogged.
L
How long did you try it "hot wired"? It may take 2 to 4 hours before you feel any cooling in the freezer compartment and 6 to 12 hours to see if it is really working, and that is in moderate temps of the 70's outside. Of course it must be level to try it out.
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Old 06-30-2012, 02:24 PM   #7
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Dinosaur Electronics makes a great replacement board for your unit: the P246 Plus. I installed one of their boards in my unit 3 years ago and was quite satisfied with its performance - adjustable temperature setting (I had a RM-2652 fixed temp model) and the board has superior construction including through holes and excellent solder joints when compared to OEM.

RVCoolingUnits.net is a great source for both quality rebuilt units and new cooling units for cheaper than OEM. I purchased one from David Force, the owner, and can only relay an excellent review of his product knowledge and business practices. The "Amish" product is a very professionally and technically built replacement. Rebuilds are not soldered as suggested in an earlier post and are throughly bench tested to test the welds before shipment.

If the heating element warmed the insulated flue but the evaporator tank did not achieve a similar temperature (judged by touching both externally with your hand), then the cooling unit has failed. The ammonia/hydrogen mixture does not have to escape for failure to occur. The rust inhibitor can precipitate out of solution and block the small passageways if the unit was operated off-level.

Changing out the cooling unit is not difficult but it is time consuming as you remove the refrigerator from the cabinet before starting the excavation of the retaining foam around the coils. If you search YouTube for "RV Cooling Unit" there are a number of videos that will walk you through all the steps.

Good luck while you resolve your issue. If you rebuild it, know it will can run for years before another failure.
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Old 06-30-2012, 02:51 PM   #8
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The ammonia/hydrogen mixture does not have to escape for failure to occur. The rust inhibitor can precipitate out of solution and block the small passageways if the unit was operated off-level.
This is the problem that "burping" is trying to repair. Burping is simple rolling the refer over so that it sits for a period of time on all its sides. As I previously mentioned, sometimes it works, sometimes it doesn't.

Quote:
Originally Posted by SeeMore View Post
Changing out the cooling unit is not difficult but it is time consuming as you remove the refrigerator from the cabinet before starting the excavation of the retaining foam around the coils. If you search YouTube for "RV Cooling Unit" there are a number of videos that will walk you through all the steps.

Good luck while you resolve your issue. If you rebuild it, know it will can run for years before another failure.
You certainly know your way around refer repairs, Seemore. Are you a involved in that business, or have you just repaired one or two before?
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Old 07-01-2012, 01:08 PM   #9
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All my experience with refrigerators stem from the headaches of ownership. Between mine and friends I have had to repair or rebuild five times in the past few years. A variety of problems from ignitor failure to pressure valve adjustments, controller board malfunction to cooling unit replacement (twice) help sharpen diagnostic insights and add technical insight. I didn't set out to be an expert, but I did gain a wealth of knowledge along the way. I've read all the technical and service repair manuals for Dometic & Norcold besides fixing home and car cooling systems as an advanced DIY handyman/mechanic.

Burping may work for a while (did it once successfully for three months), but it is an indication that trouble remains around the corner. The precipitate (a rust inhibiting powder added to the solution at assembly) is caused by clumping when the solution boils and does not flow through the tubes properly. i.e., used off-level for more than a hour. Once formed, it never goes back into solution completely and just moving the particles away from the aperture means they will travel through the system again until once more stopped in a small opening. It may be a short or long time before that happens, however the damage is done. If you get a cooling unit working again, use the time to find a quality replacement at a desirable price ahead of replacement time.
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Old 07-02-2012, 07:47 PM   #10
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Hello there!
I've been working on restoring our 1976 Dometic Fridge. In my search, I came across this guy Top's Texas Vintage Campers, Recreational Vehicles, Nolanville, TX 76559 - services
I realize Texas is BIG state, but finding parts and service for Dometic is like looking for a needle in a haystack! Hope this helps you.
Jason
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Old 07-02-2012, 07:58 PM   #11
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Top is a member here on Air Forums. He uses the same name if you want to communicate with him.
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Old 07-03-2012, 06:57 AM   #12
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From what I can tell on the web, all the replacement cooling units are rebuilds or off brand new units. If the shell of my fridge was in good shape and the shelves were not rusted bad I might consider a rebuild. Since mine is in bad shape, I will probably bite the bullet and buy a new one when the time comes. Mine is cooling well at the moment so I have no immediate plans to replace it.

So what does off level mean on these Dometics? There must be some margin as to what is considered level. Like +-10 degrees left to right and +-5 degrees front to back. I have never seen a spec on this in any manual. It would help if we knew how close is close enough. There are always acceptable tolerances but it helps to know what they are.

Perry
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Old 07-03-2012, 08:21 AM   #13
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I was told by the repair facility that replaced my fridge that Dometic makes new cooling units for newer refrigerators. I was quoted $500 for the part and $400 for labor. The fridge has to be removed and reinstalled as well as disassembled.
New cooling units don't seem to last very long. Heat thins the metal. I doubt rebuild units would last as long as new.
A new fridge was $1700 including sales tax and shipping and labor to install was $300--Ouch!
The repair facility says repairs, replacements are common in 8+ year old trailers.
I hope I didn't hasten my frige's demise by camping off level. In some off the grid camping places it is impossible to get completely level.
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Old 07-03-2012, 09:44 AM   #14
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Hey guys, my frige is a 99 and cools fine but the control knobs got damaged and spin without changing settings. Any idea where small parts like that can be purchased? Thanks.
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