Dometic RM2551 Troubleshooting

[Troy McLure]

Hi all,

Trying to troubleshoot a RM2551 in our 2016 23D. It worked a couple weekends ago on a trip but seems to have died between now and then. No cooling on either power source and the check light is off.

What I've done:

• Checked fuses; Main 15A and the 5A & 3A in the power module (all ok).
• Checked 12v power at the terminal block (13.6V, ok).
• Checked gas & pilot light (working).
• Boiler seems to work since the flue gets hot within an hour or so.
• Verified power at the 120v outlet (ok).
• I don't think there's a thermostat on the smaller units like the 2551.

This seems an awful lot like the cooling unit is either clogged or dead. Not a cheap repair but not a brand new unit either.

I'm surprised/not surprised that the Dometic died after 4 years.

The only remote thing I can think of is that we have a sloped driveway where we park it. With the front jack, I can typically get to 3-4 degrees from level. We run the unit on this slope 24h ahead to cool down before each trip. I can't find a measurable guideline for acceptable slope. Dometic only notes "vehicle needs to be leveled so it is comfortable to live in".

My questions:

1. Have I narrowed it down correctly to the cooling unit?
2. I've seen a couple older posts where people turn the fridge upside down to burp/unclog it. Anyone have success with this?
3. Is that 3-4 degree slope too much?

Thanks!

[TBone55]

Originally Posted by Troy McLure

Hi all,

Trying to troubleshoot a RM2551 in our 2016 23D. It worked a couple weekends ago on a trip but seems to have died between now and then. No cooling on either power source and the check light is off.

What I've done:

• Checked fuses; Main 15A and the 5A & 3A in the power module (all ok).
• Checked 12v power at the terminal block (13.6V, ok).
• Checked gas & pilot light (working).
• Boiler seems to work since the flue gets hot within an hour or so.
• Verified power at the 120v outlet (ok).
• I don't think there's a thermostat on the smaller units like the 2551.

This seems an awful lot like the cooling unit is either clogged or dead. Not a cheap repair but not a brand new unit either.

I'm surprised/not surprised that the Dometic died after 4 years.

The only remote thing I can think of is that we have a sloped driveway where we park it. With the front jack, I can typically get to 3-4 degrees from level. We run the unit on this slope 24h ahead to cool down before each trip. I can't find a measurable guideline for acceptable slope. Dometic only notes "vehicle needs to be leveled so it is comfortable to live in".

My questions:

1. Have I narrowed it down correctly to the cooling unit?
2. I've seen a couple older posts where people turn the fridge upside down to burp/unclog it. Anyone have success with this?
3. Is that 3-4 degree slope too much?

Thanks!

Hi
Was wondering how Troy made out with his problem. I have the same issue with mine. We have a 2018 23CB. AND I already replaced the motherboard before our first big trip last year with our NEW Airstream!!! Very frustrating. Now we are leaving for a short trip (had to cancel our big out west trip due to COVID19) and the freaking fridge is not working again. Will be checking the fuses on the motherboard this morning then we are leaving - Guess we will be traveling with a bunch of coolers.

Is Dometic the only game in town? Does anyone have a good replacement option? Why does Airstream stay with this company if their products seem to have so many problems? I guess I didn't pay quite enough for my AS.....

[BayouBiker]

Darren and MyRVWorks out in Northwestern Washington is great! but too far from New York.... https://myrvworks.com/

they do have the coveted Service manual for the RM2xxx Refrigerators. https://myrvworks.com/wp-content/upl...icana-Plus.pdf

If you're handy you can use it to trace the source of your problem, perhaps fix it, but at least have an idea what you're looking at before taking it in.

There are a number of RV refrigerator manufacturers. MyRVWorks lists them.

[GCinSC2]

TBone55,

Anything a bit more specific, for example any control panel lights coming on? Anywhere?

Are you "comfortable" trying to troubleshoot, use multi meter etc? Sorry no insult intended.

Gary

[TBone55]

Thanks guys. No, I'm good with troubleshooting. I replace the mother board last year myself while checking in with a AS tech on the phone. Checked the fuses this morning and good continuity. Got AC and DC voltage to the board. When I hit the power button it goes to Auto (I'm plugged into AC and gas is off). I hear the pilot try to light for the three times then about 5-10 min. later, the check light comes on. Which means, I assume, it's not sensing the AC. Baffled. I haven't even de-winterized for this season yet so when I get to the campground today, I'll turn the gas on and see if it will run on that. Maybe the drive will jiggle it into working condition!

[GCinSC2]

Ok have you checked AC heating element resistance? Pull one or both power leads to it and check resistance. Please provide value.

If the element is not open and nothing else shakes some sense into it (that would be a good indicator of loose connection) I could walk you thru a possible test run via AC that would force it into heating the boiler.

On my rig on a new startup it takes a while for propane to reach fridge gas valve.

[GetawA-S]

I’m not a fan of Dometic either, between the so-so performance, poor reliability and sadistic customer service. If mine goes out, I will be looking for a Koolatron to fit in the space. (I considered it for the previous Bambi because of the tiny, wimpy freezer - it would have cost about $3K at the local shop and we decided to put that to a $300 portable cooler/freezer.)
For the current trailer, the dealer wouldn’t do the swap because of the outside access panels (?). With our portable unit, the Dometic is not a hardship as long as it works.
Bottom line:A swap is possible; others have gone to compressor units with good results, You can research on the KoolAtron site for something that fit s your opening.
Botto

[TBone55]

I have not checked the resistance of the heating element. Hitting the road shortly so I will try at the campsite. I'll keep you posted. Thanks for all the help and info, guys!

[GCinSC2]

TBone55,

If you get a reading of about 40-50 ohms for the 325W heating element that's a good start. If you'd like to CONSIDER the work around test mode, please PM me and I'll talk you thru it. I'm on E.S.T.

A good heating element will not fix a board or other circuit problem somewhere else. it's waiting for power to come it's way and do it's thing.

Not an RV tech. AS Owner, yes.

Gary

[TBone55]

Good morning! Here's the update:
Fridge was 35 degrees this am! I de-winterized yesterday, turned the gas on, got the stovetop running, water heater going and hit the power button on the fridge on 'Auto'. So it works on gas. Today I will measure some resistance and PM you, Gary, with the results. Thanks again for the help!
Tim

[Troy McLure]

OP here.

I ended up getting a replacement cooling unit from RV Cooling Unit Warehouse for $460(?). Far, far better than what a repair shop would do.

The main test was to temporarily disconnect the heating element from the panel and wire it directly to a 110v source. A properly working fridge should basically super-cool within a day (no thermostat to turn it off). No cooling = bad cooling unit.

The replacement wasn't the most fun I've had but it was done within 4-6 hours. I have a few comments on the process but since TBone is back up and running, I'll skip it for now.

One note though that came up with my conversations with David @ RV Cooling - the cooling units can get fouled if they aren't level when powered on. This causes the pipes to get clogged with coolant that has permanently solidified. It is possible to take the fridge out & completely invert it to clear the blockage but it's a temporary fix. It's possible that driving around on bumpy roads can clear it too. However, those solids will eventually create another block.

[GCinSC2]

Originally Posted by Troy McLure

OP here.

The main test was to temporarily disconnect the heating element from the panel and wire it directly to a 110v source. A properly working fridge should basically super-cool within a day (no thermostat to turn it off). No cooling = bad cooling unit.

TBone55,

This is the temporary work around test I was going to try to walk you thru to get a boiler working yes or no w/o any input or controls from the board. The thermostat would now be monitoring fridge temp and run for a bit turn off for a bit etc.

Troy,

Good you got things working.

Gary

[TBone55]

Hi guys,
Another update: At the campground, turns out my next door neighbor is a guy that teaches/trains RV Technicians! He noticed me working on my unit and helped me diagnose it. So it's a 175W unit testing out with 82 ohms resistance. We were able to determine the board was good, the heating unit was good and that the issue of not sensing the AC had to be either be a bad wire from the motherboard to the 'eyebrow' unit above the fridge or the eyebrow circuit board itself. This is where the power/gas switches are and the Auto/Check lights are.
The next step is to do a continuity check on the wire and go from there.

The other thing we checked was the fridge fan, that I have never seen working. Maybe a bad thermal switch - we jumped it with a fuse so I can control when it runs. He said the position of the thermal switch should be changed closer to the cooling fins and maybe even add another fan. The whole design, as is, doesn't really remove heat from behind the fridge efficiently.

So living off of gas for now until further testing. Good thing I'm retired! Thanks again guys for the input.

Cheers!
Tim

[GCinSC2]

That's a lucky spot to camp in.

Good luck and please post the final fix.

[TBone55]

Wanted to follow through with an update on my fridge problem. Checked the continuity of the wires from the motherboard to the eyebrow unit - all good. Replaced the eyebrow unit (online for $30) - problem solved!!! Works fine on AC and gas.
Pissed I had to do anything on this nearly new fridge but happy it is now working.
Thanks again for all your helpful feedback.

Happy travels!

Tim

[GCinSC2]

Tim

A retired technology education teacher got bit by technology. [emoji851] Can I attend that real world class?

Just kidding glad you got it fixed. And just today I saw a supplier of fridge boards.

Happy camping

Gary

[Flostream66]

Tim, hi! I live just a few miles SE of you in Dutchess County. I have a 1966 Caravel, with a "vintage" refrigerator that worked great pre-shell-off resto. As of yesterday, we couldn't get it to cool. I am wondering whether you got the name and contact info for that traveling Dometic technician...I want to try to preserve mine if at all possible. Would you kindly PM me if you have the details? Many thanks - Flostream66