Need troubleshooting help with Dometic fridge

[KBennett]

My Dometic fridge is not working in my 1970 Terry TT. I was able to download an old manual that someone scanned on the web. It says if the fridge stops working I should turn it upside down but does not say how long. When I pulled it out and turned it upside down I did not hear any liquid. Should I hear something?



There is something that looks like a valve on the back:

#ad




What is this for? Are these pressurized with Ammonia or whatever is inside? Can I add more or check the level?



How big should the flame be when running on propane?

 

[Gary - K7GLD]

THey use ammonia as refrigerent - usually they are left upside down overnite - if the level is down, adding more will only be a temporary fix - as is trying to fix one by turning it upside down...



Usually there is either a leak - bad news, or there is plenty of ammonia, but running the fridge in an unlevel state has trapped all or most of the ammonia up in the coils - this allows the heated bulb to go dry and begin deteriorating from excessive heat - small particles shed off the inside of that bulb, and when proper ammonia flow is restored, those particles move on thru the system and eventually plug the capillary tube = fridge no workee... .



Flame size on gas will be about the size of a quarter...

 

[Chipstien]

I was under the impression that those particle were actually the ammonia that crystalized from being run in un-level places.

 

[KBennett]

Thanks for the reply.



How can I check the level and do I fill it through that fitting? Is there a special kind of ammonia?

 

[Gary - K7GLD]

Possibly both - but I was told the inside of the copper bulb would actually begin to burn off small particles - but the end result is the same...

 

[jrobinson2]

There are some troubleshooting guides on these sites.

http://www.rvmobile.com/

http://www.gasrefrigeration.net/

Jared



on edit

From the RV mobil site

Out of Level. If the cooling unit is operated in a stationary, out of level position (on any heat source), it will eventually become permanently damaged. Before we go any further, there is one more ingredient inside the cooling unit: sodium chromate. The ammonia solution inside the cooling unit is a mild corrosive, and sodium chromate is mixed with the ammonia solution (ammonia and water) to neutralize the corrosive effects of the solution, protecting the inner pipes of the cooling unit.



Since the cooling unit depends greatly on the effects of gravity for moving the liquids and gases inside, running it off level and stationary causes these liquids and gases to collect in unwanted areas and not be recycled back to the boiler. The liquid level inside the boiler begins to drop and become weaker. Eventually, the water in the ammonia solution begins to vaporize with the ammonia and leave the boiler. At some point, the boiler becomes dry and the temperature rises rapidly inside. The sodium chromate which was once in solution with the ammonia solution is left behind and begins to burn and permanently change state from a powder into a sort of sludge that will eventually plug the perk tube. If left to cook long enough, the sodium chromate will become as hard as steel. If the cooling unit were "saved" from this out of level condition by being leveled, or the heat source turned off, any sodium chromate that had changed state would not return to a powder in solution with the ammonia solution. This makes it possible to ruin a cooling unit a little at a time.

 

[Jumbo Jet]

I'm trying something that I hope works well. I just had my Dometic 461 cooling unit replaced with a rebuilt one from NUCOLD in Morrilton, AR.



So far everything appears OK.



Jerry at NUCOLD even installed it himself.

 

[WestTN]

You cannot add anything to the system. It is pressurized to about 600 psi with hydrogen gas. Being a 1970 system it is likely the system has lost charge. The tubing is steel, so it likely has a rust hole somwwhere. The only choices for fixing it are a rebuilt cooling unit for about 80% of the price of a new refrigerator and a lot of work to do it right, or just put in a new refrigerator.

 

[rblomquist]

Man if that thing has been working since 1970 then I'd say it's service life has been exemplary!!!!

 

[KBennett]

After sitting upside down for 24 hours I put it back in tonight and lit the burner. After 3 hours nothing felt anywhere near cool let alone cold. I think it's dead.

The problem with a replacement is that the fridge is bigger than the trailer door

Maybe I will go the route Jumbo Jet took.

Thanks to all who posted.

 

[Jumbo Jet]

Results after installation of new cooling unit - it works on 12 Volt DC, 120 Volt AC, and Propane.



I am a happy camper so far.



Now if I can just get the oven to light!



New cooling unit was $415 and installation by Jerry was $50. I could have had a new refrig for about $750 with tax and shipping. One problem was having to tear out the door frame to get the old one out and a new one in.

 

[clem]

If you can't get the thing through the door even with the door off the Frige. There must be a window they got it through,on it's back or what ever. Thats how they get these new big ones in Good luck

 

[PKleine]

I dealt with this problem in March. The old Norcold would burn gas just fine but wouldn't get cool; nor cold...



I replaced it with a slightly larger rebuilt Dometic. I had to take the door off my camper to get the Dometic in. Had to change the plumbing and add wiring for the 120 VAC and 12 VDC. I also insulated the cabinet the refrigerator fits into. It was extra work, but it was worth it. I now have a refrigerator that will double as a freezer if I choose to turn it down



I think the rebuilt was around $325 to $350, and new was in the $750 neighborhood plus shipping (and waiting).



PK

 

[crobertson1]

Kirk,

Just pop the sunroof open and lower a new one in from above. Hey, I'm just here to help!

Craig