Fridge Issue

Bingo 57 · 05-30-2021, 10:20 AM

Hi all been a while, had to do a year off due to medical. In that time the unit sat in "dry dock" so to speak.. I'm now getting it out & doing all the pre trip checks. I'm working on my 2016, 26RLS. Has a Dometic Mod#DM2852LBX Fridge. Issue is fridge works fine on electric "shore power" cools down coils in back get worm - hot so to speak but not on propane. Propane comes on I can see flame by removing the shield, I did check the 2 glass fuses in the controller and there good. I located the resettable safety on the flue & it's good as will. I adjusted the temp controller inside the fridge & no change with the flame whatsoever. At this point I'm leaning towards the control board. Any input from you all is always appreciated.
Thanks all,
Bingo

LHaven · 05-30-2021, 01:00 PM

Propane comes on? I assume it stays on, since you didn't say otherwise? If the propane is heating the element, and the fridge is still not cooling, I'm not sure how that could be the board. This is an absorption fridge, so I can't imagine how the fluid would be responding to the electric heater, but not the propane heater.

Bingo 57 · 05-30-2021, 01:53 PM

Thank you for the response, yes the fuel stays on & the flame going. But the flame does not increase under demand? And the fridge didn't cool down after 18 hours.

LHaven · 05-30-2021, 02:14 PM

Yeah, I was wrong. The flame doesn't ignite on demand, it stays on pilot and increases on demand. So that could very well be either the board or the valve.

Bingo 57 · 05-30-2021, 02:59 PM

I kinda figured if the valve was opening for the pilot, then it wasn't getting the signal from the controller to increase fuel flow. Would that be a rational line of thinking?

**JRTJH** · 05-30-2021, 05:56 PM

It sounds like there's an obstruction in the chimney. If you look at your IPB (parts diagram) you'll see a "twisted baffle" in the chimney. That "circulates the hot air produced by the propane flame so it better contacts the sides of the chimney, heating the "refrigerator boiler"... If there is a spider web or a "rats nest" higher up in the chimney, you won't get good heat flow with propane, but the electric could (not always, but often) work as designed while propane won't heat the ammonia solution.

You might want to verify that the chimney is clear from bottom to top...

Bingo 57 · 05-30-2021, 06:21 PM

Sir, I thank you for that info. I would not have thought of that. I assume I could inspect that from the top by removing the vent cover? Or is there a way to do this check from bottom, outside of the refridger ?

**JRTJH** · 05-30-2021, 06:40 PM

I don't know of any way to check it from the bottom, although I suppose a contortionist with a mirror and a bright light on a dark night might find a way....

If your trailer has a top "ROOF" vent, you can remove the vent stack cover and check from there, but there's a screen to prevent insects from getting into the trailer. If your trailer has a "SIDEWALL" vent (refrigerator in a slide) then that won't help because of the way the baffling is arranged...

The easiest way, in my opinion, is to just pull the refrigerator and check the vent stack.

I'd make an educated guess that with the trailer having been in storage (not used) for 2 years, there's a very good chance that something has built a nest in the heat stack chimney.

All that said, I'd rule out all the other possibilities before pulling the refrigerator.

I'd guess your refrigerator is "relatively new" (not built in the 1990's).... If it's a more recent model, it will have DSI ignition without a standing pilot light, so there will not be a "dual height burner"... The older refrigerators had a "low flame pilot" that increased in size when the refrigerator called for cooling.... Newer ones DO NOT have that dual stage burner. It's either "off" or "on" and when the refrigerator calls for cooling, the DSI ignites the burner and when the refrigerator is cool, the burner shuts off completely... No pilot involved.... I don't believe you have a "dual stage burner" based on guessing your trailer is not an antique.... LOL

Bingo 57 · 05-30-2021, 07:04 PM

Correct, this is a 2016 model. When this rain stops here I'll pull the vent & do some inspecting. Thank you so much for all the help. I'll do a follow up post after I get up and pull it apart.

Bingo 57 · 05-31-2021, 10:17 AM

OK so we had a brake in rain this morning, so I got up & pulled the vent cap, outside of some warped paneling at the top saw no issues. Happen to have 1 of those scopes that I can plug into my Chromebook I saw nothing up that stack. I did however learn that my cap cover got trashed in the hail storm the other day. I'm back to ground "0". Thanks for all the help!

LHaven · 05-31-2021, 10:30 AM

Is this something that could just be addressed with a bottle brush on a dowel, like a chimney sweep?

**JRTJH** · 05-31-2021, 04:11 PM

Quote:

Originally Posted by LHaven

Is this something that could just be addressed with a bottle brush on a dowel, like a chimney sweep?

That would clean any spider webs out of the chimney, so yes, that would work, just be careful not to displace the flue baffle. It "hangs in the chimney, suspended by a "T shaped wire".. Sort of a "who thought of this crap" kind of arrangement, but it's the way they have been hanging them for decades and that "wire hanger" has been working since my first Instamatic refrigerator, back in 1968. Knock the baffle off the wire hanger and it's "take the whole dang thing apart to rehang it in the chimney... It's not a "happy sound" to hear tinkling as you try to clean the chimney LOL

Bingo 57 · 05-31-2021, 05:35 PM

I saw that "baffle" thing in the scope & yes I thought it looked hokey ! I did fire up the air compressor & blew it out. Was wondering if the gas valve may not be opening up completely ? But enough to not through the "alarm" on the front of the fridge. Like I said I do see a flame, but it doesn't chill the unit down.
Again thanks for the input !

dutchmensport · 05-31-2021, 05:42 PM

Many year ago, on a previous trailer, I had trouble with my absorption RV refrigerator. Like yours, it worked on Electric, but not on gas. I wanted it working on gas. I knew a service charge would be costly and I wasn't prepared for that.

In desperation, I went to the outside of the camper, removed the refrigerator cover and took a hammer and just hit a couple things and grabbed coils and pipes and wires and just shook the sh** out of them. My wife thought I lost my mind!

But you know what? It started working to our shock! And we never had an issue with the refrigerator again for another 7 years and we traded for a new trailer, it was still working perfect!

True story! Unbelievable!

**sourdough** · 05-31-2021, 05:44 PM

Quote:

Originally Posted by dutchmensport

Many year ago, on a previous trailer, I had trouble with my absorption RV refrigerator. Like yours, it worked on Electric, but not on gas. I wanted it working on gas. I knew a service charge would be costly and I wasn't prepared for that.

In desperation, I went to the outside of the camper, removed the refrigerator cover and took a hammer and just hit a couple things and grabbed coils and pipes and wires and just shook the sh** out of them. My wife thought I lost my mind!

But you know what? It started working to our shock! And we never had an issue with the refrigerator again for another 7 years until we traded for a new trailer!

True story! Unbelievable!

LOL! I've always been a believer in "if at first you don't succeed".....you need a bigger hammer!

Bingo 57 · 05-31-2021, 05:56 PM

I think that is truly going to be my next move

B-O-B'03 · 05-31-2021, 07:13 PM

Our fridge would not work on gas, I looked and saw that the flame would light and then go out.

I used my compressor to blow out the burner and flue and it started working again... the flame was much bigger after I blew things out.

-Brian

ChuckS · 06-01-2021, 04:40 AM

Link to service manual… use it t9 diagnose ..

https://fourwheelcampers.com/NewDome...atorManual.pdf

Bingo 57 · 06-01-2021, 05:00 PM

Chuck, do you believe this will work for the "DM 2852" as well?

ChuckS · 06-02-2021, 04:41 AM

Quote:

Originally Posted by Bingo 57

Chuck, do you believe this will work for the "DM 2852" as well?

Yes..
DM —- made in Sweden
RM — USA

Schematic for DM unit is in this manual as well

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