Refrigerator Problems

[noiva]

The Dometic 3801 refrigerator in my 1989 370 has just begun to give me problems I've not experienced during my 30 years of using RV refrigerators. I've had a bad circuit board before, and a friend who had the cooling unit fail. My symptoms are that the refrigerator will not stay cool enough even if I leave the door shut to test it out. On a hot day (85 - lower 90s) the temp will rise to the 50s, and if I open the door it will rise even into the 70s and not recover until the following morning. Twice in the past several weeks I've gotten the strong smell of ammonia INSIDE the refrigerator , but not able to pick that up from the tubing outside. Appears to me that the cooling unit is shot. The ammonia smell is sort of a red flag that the cooling mix is leaking. Weird thing is that the freezer seems unaffected - staying at 0 or even below .

I have a spare refrigerator in my garage (long story ), with a new cooling unit and new circuit board. Same dimensions as the one I have in the MoHo. I can easily swap them. The big question is: Has anyone had this type of progressive ineffective cooling, and found that it was a failing cooling unit? How about the ammonia smell? That's always a symptom listed in any trouble-shooting guide. I don't mind swapping the refrigerators, but I want to be sure it not something simple .

Would appreciate any help with this .

Best,

[Condoluminum]

Unless you have been storing open containers of ammonia in the fridge, the ONLY way it can get inside the unit is via leak in the tubing. Leaking ammonia is a sure sign of cooling unit failure...

There are people who rebuild and exchange cooling units in their entirety, though actual references are hard to track down.. Search Google for "dometic" and refrigerator and RV... If you've got one in the garage, I'd begin the exchange process, as old one is not going to get unleaky by itself...

John McG

[john hd]

i'm having the same problem with my 3804 in my excella.

if it is also making a gurgling sound it is shot.

i'm planning on going with a rebuilt cooling unit from nu cold. just havn't found time to start the project yet. 500 bucks exchange.

john

[noiva]

John McG and John,

Thanks for confirming my suspicions. There is a Dometic place about a hundred miles from my home that swaps out cooling units, but they're rather pricey - so much so that a new fridge seems to make more sense if one doesn't have the luxury of a garage unit like I do.

Just wondering if you know if the circuit board for the 3800, 3801, and perhaps even the 3804 are the same? If so, I should definitely keep the board off the failing unit as a spare. I'll be replacing a 3801 with a 3800. If the boards are the same, I would at least have a spare board.

Another advantage of this exchange is the raised oak door panels in my 370 will fit the unit in my garage .

Thanks for the help.

[john hd]

tim

you can look here if you like http://www.nucold.com/index.htm

swapping out the cooling unit does not look that hard. i think the hard part will be getting the fridge out of it's moorings.

john

[noiva]

Originally Posted by john hd

tim

you can look here if you like http://www.nucold.com/index.htm

swapping out the cooling unit does not look that hard. i think the hard part will be getting the fridge out of it's moorings.

john

Thanks for the link. They certainly do appear to be cheaper than the "official" Dometic service facility around here. I've had to remove another refrigerator in a trailer several years ago, and it really wasn't too bad.

Tim

[lewster]

Hi Tim,

I just picked up on this thread. You probably have a leak in the low temp evaporator section that is responsible for cooling the fridge section and the hole is in the foam block. That's why you smell the ammonia inside and not outside. When you remove the cooling section to replace it the leak spot should become apparent.

I'm not sure if the control boards are compatible. Remove the black cover and look at the part #'s to see if they are the same.If you can't find them, send me the model, serial and product #'s from both units and I'll check in my manuals for the part #'s.

Don't feel too bad about a 30 year old unit failing; that's great longevity! I've been replacing a bunch of cooling units in 1 & 2 year old units lately, but at least they are under warranty!

[noiva]

Originally Posted by lewster

Hi Tim,

I just picked up on this thread. You probably have a leak in the low temp evaporator section that is responsible for cooling the fridge section and the hole is in the foam block. That's why you smell the ammonia inside and not outside. When you remove the cooling section to replace it the leak spot should become apparent.

I'm not sure if the control boards are compatible. Remove the black cover and look at the part #'s to see if they are the same.If you can't find them, send me the model, serial and product #'s from both units and I'll check in my manuals for the part #'s.

Don't feel too bad about a 30 year old unit failing; that's great longevity! I've been replacing a bunch of cooling units in 1 & 2 year old units lately, but at least they are under warranty!

Lew,

Thanks for the info. I particularly appreciate the info on the source of the ammonia smell. That had me puzzled. Actually, this is the first time I've had a cooling unit failure in the 30 year period I've been using trailers and the MoHo.

I did some research on the boards after writing in to the Forum yesterday, and found that the boards for the 3800 and the 3801 are NOT the same. It makes sense because the controls on the top of the two units are very different.

Thanks again for the help,

[lewster]

No Charge!!!!:d :d

[john hd]

tim

perhaps lew can confirm, i believe dinosaur makes boards for our fridges.

john

[lewster]

I'll check my application list and get back to you later.

[noiva]

I've discovered that even though the boards are not exchangeable between my bad Dometic 3801 and the "spare" 3800 with a new cooling unit and board, that the cooling units are the same . I have already started swapping the two refers out, pirating things from the failed one to the 3800. Now I wondering if it's that hard to simply change the cooling units from the good one to the bad one? Has anyone had any experience changing out cooling units? I have the directions, both from research on the Internet, and from a set left in the spare refer. Doesn't look too difficult, but I'd feel a lot better if someone has done this and could give me some feedback .

Thanks,

[john hd]

Originally Posted by noiva

I've discovered that even though the boards are not exchangeable between my bad Dometic 3801 and the "spare" 3800 with a new cooling unit and board, that the cooling units are the same . I have already started swapping the two refers out, pirating things from the failed one to the 3800. Now I wondering if it's that hard to simply change the cooling units from the good one to the bad one? Has anyone had any experience changing out cooling units? I have the directions, both from research on the Internet, and from a set left in the spare refer. Doesn't look too difficult, but I'd feel a lot better if someone has done this and could give me some feedback .

Thanks,

i'm changing mine this week if i have time, look for a thread on it this weekend.

john

[noiva]

Originally Posted by john hd

i'm changing mine this week if i have time, look for a thread on it this weekend.

john

I've about decided to remove the bad unit.... sort of a test of difficulty. If that works, I'll go ahead and remove the good unit so I can put it in the refer with the bad one. That way I can keep the same box I've had - which is newer, in slightly better shape, and has a few more bells and whistles. If removing the bad unit goes poorly, I'm just going to do the swap. I'll keep the progress, or lack thereof, posted here.

Good luck with yours. I'll be looking for your thread.

[john hd]

tim

you will need a caulk tube of thermal mastic. i can get the address off mine.

john

[noiva]

Originally Posted by john hd

tim

you will need a caulk tube of thermal mastic. i can get the address off mine.

john

Thanks, I had read about thermal mastic in both sets of directions, so that was going to be my first hunt in the morning. I've located some on the web, but I'm hoping I can find some locally. If you could post the address off yours, that may be where I'll end up. I have no hint of the availability of that stuff. I'm hoping it's fairly easy to find.

[lewster]

Tim,

Do a bunch of measuring of both cooling units before the swap. Measure the foam block and be sure that the dimensions are exact. Then check all of the mounting holes that penetrate the box and go inside the freezer section and those between the fins in the refer section . It is CRITICAL that these be exactly the same! Also, note when you start removing screws that some are of different lengths. Be VERY CERTAIN that you mark where these go and put them back exactly as you have removed them. Very important!!!


Other than that, let me know if you can't get the mastic. This too is critical, as it is the only medium that will effectively transfer the heat from out of the refer to the cooling unit, thus getting the box cold. Too much or too little and you decrease the efficiency of your unit.

[noiva]

Originally Posted by lewster

Tim,

Do a bunch of measuring of both cooling units before the swap. Measure the foam block and be sure that the dimensions are exact. Then check all of the mounting holes that penetrate the box and go inside the freezer section and those between the fins in the refer section . It is CRITICAL that these be exactly the same! Also, note when you start removing screws that some are of different lengths. Be VERY CERTAIN that you mark where these go and put them back exactly as you have removed them. Very important!!!


Other than that, let me know if you can't get the mastic. This too is critical, as it is the only medium that will effectively transfer the heat from out of the refer to the cooling unit, thus getting the box cold. Too much or too little and you decrease the efficiency of your unit.

Lew,

Thank you so much for this information. Let me ask you a very unfair question . The good refer I have is a 3800 Dometic, originally from a 1986 trailer belonging to a friend. He had a new cooling unit put in by the Dometic repair facility in Ashland, VA (I'm assuming they installed it correctly?). It also has a new circuit board. I know it works, because I used it during a 9-day period we were without power from a hurricane. I've already placed it in position in my MoHo, but have not secured it, nor reconnected gas/electric lines. All the shelving, bins, etc. from the MoHo will fit, and even the doors will transfer. The only thing I'll lose is an external drain for the auto-defrost, and controls that show a little more info, but don't really do any more. I'm getting a little nervous about all the precision necessary to do this cooling unit swap . Would you recommend that I just use the refer that's working rather than try this cooling unit swap? I would hate to attempt this and not get it right when I have a perfectly good refer I can just finish installing. I realize this is putting you in possibly an awkward position, but I really would like your opinion. I promise I will not hold you accountable either way ! I just don't want to potentially mess this up when I've already got a working refrigerator all but installed.

Best,

[lewster]

Tim,

Give me a call on this. 239-601-8650.