Refrigerator Cooling Question

guodf · Joined: 26 Mar 2007 Posts: 16

Okay, so I have a 1995 National RV with a Dometic RM2611 refrigerator. I changed the motherboard out with a Dinosaur Electronics Micro P-711 which solved my check light problem and the fridge worked nicely. I took the MH up to Canada for 3 weeks, and the freezer kept things frozen, and the refrigerator kept things nice and cold. I just got back from a weekend trip and the freezer only got cold enough to keep things cool, and the refrigerator did not even get cold. What can I do to fix this problem?

Stan Birch · Guest

From an optimistic perspective, it could be something as simple as not enough heat.

1. I would start out by banging on the heat exchanger chimney and making sure all the loose rust has been dislodged.

2. Clean out the burner tube even if it doesn't "look" compromised. Remove any rust and crud that might have accumulated in any of the burner holes, and of course, any rust and crud that has fallen from the chimney.

3. Remove the gas orifice and soak it in some kind of heavy duty solvent: lacquer thinner, toluene, or whatever. Then blow out the orifice with compressed air, as well as the area on the gas valve where the orifice attaches before reinstalling the orifice.

If you have a quiet lazy blue burner flame or even worse, a flame with a lot of yellow, you have a gas/air supply problem. When properly adjusted:

1. The flame should be bright blue with just a bit of a roar to it;

2. Adjust the air shutter to the least amount of "roar" consistent with eliminating >95% of any yellow-coloured flame.

guodf · Joined: 26 Mar 2007 Posts: 16

Okay: Here's what I did:

1. All loose rust has been dislodged

2. Burner tube is brand new along with the electrode and thermocouple

3. Did not clean the gas orifice; not sure where that is. However, I don't think that's the problem becasue the fridge does not get cold when plugged into 110 socket

4. I do have a bright blue flame with just a hint of yellow and a bit of a roar.

So from a pessimistic point of view, what do you think the problem could be?

KWMyers · Joined: 24 Oct 2006 Posts: 138 Location: Missouri, USA

If the freezer is cold, the burner/electric is working OK. The refrigerator portion gets some of the cool air from the freezer unless there is a blockage. Try defrosting in case there is ice built up blocking the cold air to the frig section. If not frosted, look for how the air gets from the freezer to the frig and make sure a piece of foam or such isn't blocking it. Those are my first thoughts. I check my manual to see if I'm missing something. Later....

Stan Birch · Guest

guodf · Joined: 26 Mar 2007 Posts: 16

Is there a way I can pressure test the coolant system or should I try replacing the thermistor first? No yellow powder anywhere.

Stan Birch · Guest

KWMyers · Joined: 24 Oct 2006 Posts: 138 Location: Missouri, USA

Woops, my bad. I misread the original symptoms after the weekend trip.
It does make sense to check the burner. One way to do that is to disconnect the gas valve and apply 12v directly to it and light the burner. It should run 100% of the time. If the unit doesn't get cold within an hour or so, the closed system is probably clogged. You would smell ammonia if it had a leak. Either way, replacement would then be the answer. If it gets cold with the burner running 100%, then you have a control problem which suggests thermocouple, etc. If the burner won't light with a match with 12v applied, there would be a gas flow problem. This test should help you isolate the problem area.

guodf · Joined: 26 Mar 2007 Posts: 16

Hummm, now you got me thinking, 'cause the freezer gets cold but not freezing. However, the fridge barely gets cold. I do not smell any ammonia and I just replaced the thermocouple about 2 months ago. Is it possible that I got a bad thermocouple? Does the thermocouple only come into play when using gas? The reason I ask is becasue when I am plugged in, I get the same result as if I was running it on gas where the freezer gets very cold but does not freeze and the fridge barely gets cold. What I don't get is it worked just fine in May, then I went to Bakersfield CA just recently, and had nothing but problems. URGH!

Stan Birch · Guest

KWMyers · Joined: 24 Oct 2006 Posts: 138 Location: Missouri, USA

The gas burner and the electric element both will create the necessary heat to make the unit cool. (That sounds weird, eh?) In any case, if the burner area is continually hot but little or no cooling in the freezer,your system is probably clogged which = replacement. I had one that was intermittently clogged and it took the dealer (warranty) a bit of time to diagnose, but they ultimately replaced my Dometic.

Alterego · Joined: 12 Jan 2006 Posts: 596

After everything you have tried, I would post your problem at http://www.rvmobile.com/. They are refrigerator parts and repair. The forum there would be able to answer your question/problem.

guodf · Joined: 26 Mar 2007 Posts: 16

My test results are back. I checked and double checked my system made sure I was level and restarted the fridge using the gas setting. I started it last night at 9:30pm on level 4 and I checked it this morning at 6:30 (8 hours later) the cup of water that I put in the freezer was frozen and the drinks that I put in the fridge were cold. So I concluded that being in the 125 degree temperature had a lot to do with what I experienced. So now my question is how do I avoid this from happening in the future? I travel to Arizona quite a bit and can not afford to keep throwing food away. Anything you can suggest would be greatly appreciated.

elh3946 · Joined: 06 Nov 2005 Posts: 1650 Location: Sioux Falls, SD

KWMyers · Joined: 24 Oct 2006 Posts: 138 Location: Missouri, USA

I've heard of adding a fan to the coils in the outside access to the fridge to aid cooling. I even had one for a while but couldn't really tell if it helped or not. If you're in 125 degree heat, you're asking your freezer to create a temperature differential of over 100 degrees to keep items frozen. Sounds pretty unlikely to me with an RV style fridge.