Dometic RM2807 refrigerator Problem

[bryanduchesne]

Dometic RM2807 refrigerator Problem


I have a 1994 Bounder and have run into a problem with my refrigerator.? I purchased it recently so am new to this unit.

1) I can run the unit on propane and AC.? The freezer gets cold enough to freeze water.? The refidge never gets below 50.
?
2) If I change thermostat settings (ex. 3 to 5) it seems that the unit stops cooling (even though when on propane the flame continues to burn) and the freezer thaws.
3) After "x" hours (yesterday it was fine for 12 hours) it seems to stop cooling and the freezer thaws.
I have read that possibly a new board will fix this.? I smell no ammonia and do not see any yellow dust.? It is over 12 years old so there may be concerns that the crystallization problem could be occurring.? I cannot pull the unit or tip it over.? Just too old. So caught between getting a new board or a new fridge.

I would love to here from someone who had this same problem and hopefully were able to fix it.?

Thanks.


In Response to Gary's points:

1) I checked the doors with a dollar bill and it seemed to hold the dollar firmly.  It definitely took a little tucking.


2) The thermostat was actually lying on the refrigerator shelf.  I have attached it to the fins on the far right as you look in.  We'll see if that may be the culprit.

3) I have screening on both the roof vent and the side vent at the base of the unit.  Yesterday, I ran a fan into the side vent all day to see if that would help the airflow.  It didn't seem to have any additional benefit.

Thank you so much for getting back to me

 

[Gary RV_Wizard]

Here's an excellent source for trouble-shooting help on RV fridges.

http://www.rvmobile.com/Tech/Trouble/TROUBLE.HTM

What make and model of fridge is it? Dometic or Norcold and what model number (if you can find it).

I not convinced a new board would solve this sort of problem. Failing circuit boards usually don't cool at all, or may work in gas mode only or electric mode only. Partial cooling is not usually a circuit borad problem. However, since at least one occasion your fridge appeared to work for a time and then quit, it is a possibility.  Dinosaur makes excellent replacement boards for both Norcold and Dometic fridges.


The #1 cause of cooling problems in old fridges is poor door seals. The quickie diagnostic for this is to close a fairly crisp dollar bill in the door and see how hard it is to pull out.  There should be at least some reisstance to pulling it out - the more the better. If it slips out easily, your door seals are leaking badly.

You could have thermostat problems. If there is a metal tube device clipped to a cooling fin inside the fridge, try sliding it either up or down the fin and see if that has any effect, positive or negative. Or the t-stat may simply be bad.

Check the ventilation in the rear (outside wall) of the fridge and make sure that there is no birds nest or something similar blocking the air flow up the back. Air must come in through the outside door and rise up along the wall, exiting at the vent on the roof. Sometimes an animal nests in there and blocks the air flow, which just about halts cooling.

 

[bryanduchesne]

I have continued my testing of the refrigerator by bypassing the control panel and directly connecting the A/C power.

Not much has changed.? The freezer will not go below 25 degrees and the refrigerator hovers around 52.

I believe I have reached the point that I am out of options.? I will try blowing the fan through the lower vent (when and if it ever stops raining up here in NH.? After that, I believe it will be time for a new unit.

Thanks for your help

?

 

[Karl]

Oops, you're not out of options quite yet.

You mentioned that the thermostat was lying on the refrigerator shelf, and that you attached it to the cooling fins on the inside. WRONG! If you attach it to the cooling fins, it thinks it's much colder inside the fridge than it really is. The thermostat should be sensing the free air temperature inside the unit. Try moving it about 1" AWAY from any internal surface, so that it's not touching anything.

On regular household refrigerators, there is a second 'thermostat' that's mounted on the condensor coil on the back of the refrigerator; not inside. It's purpose is to prevent total system freeze-up, and you DO move that one up or down to get the desired effect. You don't have this on an RV fridge. Try what is mentioned above and see if that doesn't solve your problem.

 

[Ned]

On our Dometic, the thermostat is attached to the rightmost fin.  It's not in the free air.

 

[Gary RV_Wizard]

Karl,
Unlike a residential fridge, in these the sensor attaches to a cooling fin. I never heard an explanation as to why, but that's the way both Dometic and Norcold do it. Location on the fin is also important, for some reason.

But it sounds as though hiis cooling unit may be defective if direct power to the element doesn't cool.

Bryan:
Here's anothe site with trouble shooting information:  http://www.rverscorner.com/refer.html
Basically, you can get an idea if the cooling unit is functioning by feeling the amount of heat in the boiler and condesnor sections of the tubing on the back of the ridge.

 

[Karl]

Gary and Ned,

Thanks. I stand corrected. It IS clipped to the right side of the cooling fins, but is only making indirect contact with it through the plastic clip.

 

[bryanduchesne]

I have moved forward with the advice/web site provided me by Gary (thanks again for so much help). 

After working all night, the fridge quit cooling again sometime this morning.  After testing the cooling system with the "touch" method (provided in the link), I felt no heat coming from the cooling coils and very little heat coming from boiler.  The chimney was hot to the touch.  Believing I am very close to being out of options, I tried the old french way of fixing things handed down from generation to generation.  I banged the boiler, the cooling coils, and the chimney as hard as I dared ( I think I dared pretty hard..)  The unit kicked in again and started cooling.  The boiler became warm and the cooling coils heated up somewhat.  It only lasted for about 20 minutes and then the cooling stopped again.  The boiler was barely warm and the cooling coils were cold.  If I am not mistaken, I believe this proves the cooling system is gone.  With this said, I believe my best option having a 12-14 year old unit, is to buy another. 

This brings me to my next question.  Does anyone have an opinion of what to get.  Dometic, Norcold, other.  It seems that through my research for a fix on my current unit, I have seen many problems occurring with this technology used by these types of  refrigeration units.  Is there anything else out there that would be consided superior to just replacing in kind.

Thanks

 

[Karl]

Is there anything else out there that would be consided superior to just replacing in kind.

Some people have replaced their rv-type refrigerators with regular home units, but they run on 120V - good for long stays on shore power, but not so good if you have to run them off batteries through your inverter.

There are also some compressor units now that run off 12VDC or 120VAC. Here is a link to the Norcold site for them: http://www.norcold.com/builtin.cfm Googling "ac/dc refrigerator" will turn up many other links.

 

[Gary RV_Wizard]

Probably 4 out of 5 of these absorption fridges work fine, often for many years.  Then there are those that fail within 2-3 years and some people have even had multiple failures.  Faulty installation?  Something the owner has done or not done? Nobody seems able to say or even guess.  I've never had a cooling unit failure or much of any problem with the 4 different RV fridges we have owned. The few problems we had were mechanical - a cracked door inge and a failing interior light swtch. Our current Dometic side-by-side works extremely well, cooling quickly and efficiently. We have to run it on lower than the recommended setting because it gets too cold otherwise.

There was  a period of time in the mid 90's when fridge circuit board failures were rampant but both Dometic and Norcold seem to have gotten over that.

 

[TNROY]

Gary has provided you excellent web sites for your research. Here's one more to try www.bryantrv.com. Go to the "service documents" section. From that site you can download complete service manuals if you know the model number of your refridgerator. I wouldn't give up just yet.