Dometic MB 52 Not working

[68-Ovrlndr]

I recently purchased a 26' 1968 AS international Overlander. It is in pretty good condition with all the original equipment. All of the appliances are in fair/good working condition except for the refrigerator. The refrigerator is a Dometric model MB 52. The electric heater and LP gas burner both work, however the unit does not cool at all. How can I determine exactly where the problem is with this unit? I would like to repair this unit if at all possible, as the current cabinetry is built around this model. If I have to replace the refrigerator, some inevitable remodeling will have to be done, which I would like to avoid if at all possible. I recently read that if you turned the refrigerator upside down that may help by moving the ammonia around. So I spent the better half of an afternoon, disassembling the kitchen to get the refrigerator out. I flipped it upside down, and on all sides as recommended, but it still does not cool. You can easily here what I assume is ammonia sloshing around in the coils as you turn it upside down. Is there any hope for this unit? In general appearance it seems to be in good conditions and hardly ever used. It has probably not been used in at least 4 of 5 years...probably more.

[azflycaster]

RV refrigerators will take hours to get cool, did you give it enough time?

[BIGED52]

Richard is correct. It will take hours for the ammonia to heat up sufficiently to cause the interior to cool down then you need to check the cooling with a thermometer. If it will make ice I suppose you could skip the temp test. Happy Trails, Ed

[68-Ovrlndr]

Yea a gave it at least 12 hours with no change in temperature. I am looking at having the cooling unit replaced and/or repaired. Any suggestions?

[Sixty3TW4US]

I'm having the same problem, my refer worked 4 months ago. I have tried a couple times and still nothing. It stays lit just won't cool. It's propane only, original to my 63 TW. No ammonia smell, it' been lit now 16 hrs nada!!!

[Inland RV Center, In]

RV reefer cooling units, do go bad.

The only real fix is replacing it.

If the colis at the rear of the reefer are hot, then the system is functioning, but there is an internal blockage.

Some say turning it upside down and burping it, will fix it. Perhaps, but since the problem is blockage, it will only return again.

Andy

[Sixty3TW4US]

My refer is only 46yo ha ha !! Andy do you know if the refer gets lit say once a month while the trailer is not in use, will that help it not to develope blocks or bubbles. In other words does non use add to this problem??

[Inland RV Center, In]

Originally Posted by Sixty3TW4US

My refer is only 46yo ha ha !! Andy do you know if the refer gets lit say once a month while the trailer is not in use, will that help it not to develope blocks or bubbles. In other words does non use add to this problem??

Reefer cooling units, are sort of like humans.

On ocassion the die at an early age, but most live a long time.

Non use of the cooling unit, I don't think adds or subtracts from it's intended job.

However, regardless of use, the flue, burner and orifice, should be routinely cleaned for maximum efficiency.

Rust has a way of getting into the burner and orifice which impedes the gas flow, which reduces the temperature of the flame, which reduces the colling efficiency.

Andy

[Sixty3TW4US]

Thanks Andy, I will give it a cleaning etc. to eliminate what might be in there, than if needed i will do a R & R of the refer, burp it and try again. BTW you put a new axle in my 63 TW last year and all is doing fine.

[Inland RV Center, In]

Originally Posted by Sixty3TW4US

Thanks Andy, I will give it a cleaning etc. to eliminate what might be in there, than if needed i will do a R & R of the refer, burp it and try again. BTW you put a new axle in my 63 TW last year and all is doing fine.

Thanks.

We love to make Airstream's happy, and to make their owners even happier.

That's been my goal for over 43 years.

However, sometimes, however rare, things happen.

Nothing on earth is perfect, not even a diamond.

Andy

[Sixty3TW4US]

Well to my surprise this worked. From my above listed posts my origional refer in my 63 TW was not working, it would light but not cool. I have read here about burping the frig, I didn't want to take it out and do the burp thing. We went camping this weekend part of the trip there was on a bumpy road. I guess the bumps burped my refer because when we arrived i lite the thing and low and behold the refer got cold and it also made ice. The bumpy road did the burping for me!!!

[Inland RV Center, In]

Originally Posted by Sixty3TW4US

Well to my surprise this worked. From my above listed posts my origional refer in my 63 TW was not working, it would light but not cool. I have read here about burping the frig, I didn't want to take it out and do the burp thing. We went camping this weekend part of the trip there was on a bumpy road. I guess the bumps burped my refer because when we arrived i lite the thing and low and behold the refer got cold and it also made ice. The bumpy road did the burping for me!!!

The bumps more than likely removed some of the rust from the reefer burner and/or orifice.

Reefer burners should be taken apart and cleaned every 3 to 4 years.

Who know when yours had that cleaning.

The burner must burn efficiently, or cooling will not happen.

Just because you may see a flame, does not mean that the flame is hot enough.

Andy

[LiisaNiemi]

Last year I bought a darling 20' Land Yacht that has the same fridge, MB52 and it worked on electric only last year. This year nada, it was about 55 degrees in there and I had to use coolers and ice. Yuck! My cabinetry also is built around the fridge so I don't want to replace it unless I must. Here are a few questions for you experts out there! 1. Any way I can test if it's working or not? 2. Any known repair shops in the New England area? 3. If I do replace with a Dometic, which model should I choose? 4. Can I get away with a small one way (electric only) fridge from an appliance store? and if so what model would you all recommend. THANKS!

[68-Ovrlndr]

The simplest test is to turn it on either with electricity or propane. With gas you will have to physically light the burner and you will see a nice blue flame. As for electricity you will have to wait at least a few hours for the electrical element to heat up. In either case you should definitely be able to feel that the counter directly above the fridge is slightly warm. My trailer has a large vent plug which allows you to be able to reach your hand down and feel the heating "chimney". If working it should feel quite warm. If it doesn't get warm via electricity, probably the heater element has gone bad, but these can be easily replaced. If if doesn't get warm via gas, you probably need a new gas burner, again easily fixable. Now just because some source of heat (electricity or gas) is working the fridge still may not cool. There may still be a blocked ammonia pathway preventing the evaporation of the ammonia. To fix this will require some time to physically remove the complete fridge unit. Then turn it upside down for a few hours, then on each of its sides for a few hours each and maybe repeat each a few times. Also while the unit is inverted in each of these positions lightly tapping on the coils with a rubber mallet for a few minutes may help. All of this will hopefully release any blockage if there was one. Now hook it back up and see if it works. Give it at least 12 hours to see if it cools. However, if it doesn't don't give up the issue you can still have it fixed. You will need to remove the coil and send it off to be serviced, they will remove the old ammonia, fix any leaks, and refresh with new ammonia. This option is not cheap but still a bit less expensive than a new fridge and cabinet retrofitting. I ultimately had to send my coil off for repair. Packing and mailing the coil itself was over $100. However, when I got it back it worked perfectly. The issue with my fridge was with the coil as my gas and electrical components all worked fine. Now the electrical & gas repairs are fairly straight forward and should not be too expensive. If the coil needs to be reconditioned, then you need to ask yourself what you want for your trailer. If you want to keep the trailer as original as possible and keep the "retro" look then you'll probably need to remove the fridge and send the coil off for repair. However, if you don't care that all the original equipment is maintained, then if you have to remove the fridge to get at & repair the coil, you might as well spend a few extra bucks and get a new modern fridge.

[CHRISRICO7]

Do you still have the mb52 I can rebuild them. We have been rebuilding since 1978. I’m also looking for parts on MB52 I’m looking for a freezer door for a customer if anyone has one please dm me thanks.