Dometic DM2683 No Light on Propane

[sameo416]

Dometic DM2683 2 months after delivery.

Fridge has worked fine on A/C, D/C and propane for several weeks. Last night on propane the check light came on. Tried cycling power several times.

Each time the fridge goes through the ignition cycle, can hear the igniter firing but with no light. Then check light comes on again. One time it re-lit and the burner operated for a few minutes then went out. Check light.

Lots of propane. Stove works fine. The flames oscillate in length slightly, couple of mm, that makes it look like the pressure is fluctuating. Never seen that before.

Last time around starting hearing a couple of ‘whumps’ during the ignition cycle. Watched a cycle from the outside and realized the whump was gas igniting outside the combustion chamber.

There is power. The fuses are fine. Gas valve is open. The ignition of gas outside the burner suggests there is gas flow.

In terms of further troubleshooting based on all the forum entries:

Check the burner assembly after removing the cover.
Check the electrode gap.
Clean out the burner tube and orfice.

Apart from that I’m at a loss what else to do. Open to any suggestions, with thanks.

We’re in the woods with no cell service so drove into town to gather information.

[MVA]

Since you are "in the woods", I assume you do not have shore power.
Do you have a generator to be able to run the frig on AC? If so, does it still work on AC?
If the frig works on AC, what is your current altitude compared to where you lasted ran the frig on propane? The frig is sensitive to propane inlet pressure (per Dometic and also I have found that to be true running from sea-level to 7000').

[sameo416]

Thanks!

Have a gennie but limited hours in the campground.

About 3,700’, 1230m elevation so not that high.

Fridge works on a/c.

[MVA]

Originally Posted by sameo416

Thanks!

Have a gennie but limited hours in the campground.

About 3,700’, 1230m elevation so not that high.

Fridge works on a/c.

The propane regulator is finicky. Your comment on the stove flame is telling. The frig has a very low flame height (compared to the other appliances) and is therefore susceptible to incorrect propane pressures. Also the oscillating flame could be indicative of a partial clog in the regulator value. The regulator is a simple needle value that opens/closes based on a spring tension adjustment dictated by the downstream pressure.

Will probably need to be measured/adjusted. Simple to do with the correct tools, but you are not at home, and in the woods per se.

[sameo416]

Thanks. It is sensitivity to pressure that I think to be causing the problems, compounded by a potential regulator issue. I’ve just changed to a full tank and haven’t checked the stove to see if it’s still oscillating.

After cleaning out the burner area it relit and burned all day with no issue. Come evening it shut down but this time it was an empty tank. Changed tanks and again couldn’t get it to light.

After multiple attempts and a couple of ‘whumps’ which I think now were likely due too lean mixture as the line was purging, it lit without issue.

Lesson learned. Sensitive to pressure and may need more than 5 or 8 attempts to light after a tank change.
Possible regulator issue to watch.

Once home I’ll try a manometer and check the feed pressure to the fridge.

Thanks for the advice!

[MVA]

Good luck. FYI: There is a 1/8" NPT pressure test port on the side of the regulator. A 1/8" NPT - tubing fitting is helpful in connecting a home-made manometer to the regulator. Some videos on-line have you connect to the cooktop line to test the pressure; not a great idea IMO. The regulator pressure adjust screw is behind the black cap on the regulator.

One last item. The regulator does not have a bleed-off function. Hence, when you try to reduce the pressure by turning the adjustment screw, you will not see any pressure reduction. You need to bleed off the excess gas in the line via the cooktop or other means to drop the pressure after turning the adjustment screw. You can turn the adjustment screw to increase the pressure and you will see a pressure increase immediately.

[rubicon327]

Originally Posted by MVA

Good luck. FYI: There is a 1/8" NPT pressure test port on the side of the regulator. A 1/8" NPT - tubing fitting is helpful in connecting a home-made manometer to the regulator. Some videos on-line have you connect to the cooktop line to test the pressure; not a great idea IMO. The regulator pressure adjust screw is behind the black cap on the regulator.

I never really understood the stove idea...maybe just convenience? The older Atwood DV-20 (2 burner), DV-30 (3 burner) and the newer Suburban SDS2 cooktops have small built-in pressure regulators. That is going to impact any reading as you will be downstream of that second regulator. Measure at the test port on the fridge line if possible.

[MVA]

I don't understand tapping into the stove either. First, breaking and remaking compression fitting inside the trailer is a bad idea IMO. Second, you need to vent the line to drop the pressure; venting propane inside the trailer is also bad idea.

[sameo416]

Thanks for the discussion and pointers. It’s continued to fail and require multiple attempts to re-light. Last failure at 0230 last night. In the relight process I’m still getting lean ignition (whumps) several times before the burner lights. So troubleshooting when I get home.

One person on fb mentioned similar behaviour resolved by replacing the control board.

[MVA]

I would be interested in the solution for my future reference. Could be the board, but see if the refrigerator works when you get home. I had a very similar problem when we picking up our trailer from ETI. We drove south the Death Valley NP (it was March) and everything worked great. Drove to Flagstaff AZ (6900') and frig started to fail just like yours. Drove home to NM next day (7000') and frig continued to fail. Built manometer and adjusted pressure (from 13" w.c. to 11.5" w.c.). No problems since. Hope your solution is as simple.

Edit - forgot to mention from our experience. So when we got home, I called both Dometic and Marshall Excelsior (regulator manufacturer). ME engineers told me they ship regulators set at 13"-13.5" w.c. Dometic tech staff told me that gas pressure needs to be 11.25"-11.5" w.c. Since propane pressure was too high, gas at flame was too rich which was exasperated at higher altitude. 2 cents.

[Iowa Dave]

We have a 2013 Escape with a Dometic 8555 refer. It has a test port. In May a friend stopped by and he wanted to adjust his pressure. No test port on his refrigerator line so we screwed the manometer fitting into the regulator after removing the plug on on the regulator. Showed a valid reading. Everything had been working well at our 600 foot elevation. We removed the black plastic cap on the regulator and adjusted the pressure up and down and the owner referenced the position on the screw slot on the regulator adjustment screw. He then knew how much of a rotation on the screw it would take to gain or lose about an inch or less of water column pressure. And headed for the west coast. As mentioned, you do have to relieve all pressure to get an accurate readjustment. The screw was a conventional flat slot not a Phillips or Robertson.
As my dad always told me, “count the turns all the way in and you’ll be able to get back to where you were when you started.” Maybe this won’t help but it is what we did that evening.
Iowa Dave

[sameo416]

Postscript.

Used one of the LP gauges on Amazon (Yellowjacket) to check the delivery pressure at the fridge test port. Picked up an 1/8” adaptor to connect directly although the thread pitch was different. Delivery pressure was 13”wc as others suggested. Lit the fridge and it took almost all 45 seconds to finally light after a couple of over-rich ignitions (whumps)..

Adjusted the reg second stage down to 11”wc at the reg test port. About 1”wc per full turn of the adjustment. CW increases, CCW decreases.

It’s a Marshal Excelsior MEGR-253 btw. The manufacturer docs says it’s set at 11”wc from factory which seems incorrect.

Adjusted the reg down to 11”wc at the test port and at the fridge test port. Fridge lit immediately when turned on.

Then lit two stove burners on high and the pressure dropped to 10”wc. A little confused by that drop as the reg should provide adequate flow to maintain set pressure.

So adjusted the reg up to 11.5”wc and tested the fridge again which lit immediately.

The weird oscillation in the stove flame I noted previously is gone.

Based on this troubleshooting the sensitivity of the fridge to pressure setting seems confirmed. The regulator factory set to 13”wc is also confirmed. Our next trip is in a couple of weeks will confirm there are no more 2 am fridge faults.

Thanks again for the advice!

[Iowa Dave]

I am running 11.8 inches water column on our first generation 21. I have camped up to about 8,000 feet with it and run all systems on propane at that time. (Furnace refrigerator, water heater and stove.) I think when we checked it for multiple appliances I ran the furnace, refrigerator and the big stove burner and it was solid at 11.0. I’ve left it alone ever since. That’s where it was set when we got the trailer in 2017. I replaced the regulator on the 19 when we had it. I never checked the setting because I didn’t have a manometer. We got the manometer with the 21 and I checked the 19 regulator before we sold the trailer. It was factory set at 11.0 and that’s where I left it.
Iowa Dave

[sameo416]

Originally Posted by MVA

I would be interested in the solution for my future reference. Could be the board, but see if the refrigerator works when you get home. I had a very similar problem when we picking up our trailer from ETI. We drove south the Death Valley NP (it was March) and everything worked great. Drove to Flagstaff AZ (6900') and frig started to fail just like yours. Drove home to NM next day (7000') and frig continued to fail. Built manometer and adjusted pressure (from 13" w.c. to 11.5" w.c.). No problems since. Hope your solution is as simple.

Edit - forgot to mention from our experience. So when we got home, I called both Dometic and Marshall Excelsior (regulator manufacturer). ME engineers told me they ship regulators set at 13"-13.5" w.c. Dometic tech staff told me that gas pressure needs to be 11.25"-11.5" w.c. Since propane pressure was too high, gas at flame was too rich which was exasperated at higher altitude. 2 cents.

It appears that is exactly the situation we experienced. After dropping the delivery pressure to 11.5 fridge lights immediately.

[rubicon327]

Originally Posted by sameo416

Postscript.

Used one of the LP gauges on Amazon (Yellowjacket) to check the delivery pressure at the fridge test port. Picked up an 1/8” adaptor to connect directly although the thread pitch was different. Delivery pressure was 13”wc as others suggested. Lit the fridge and it took almost all 45 seconds to finally light after a couple of over-rich ignitions (whumps)..

Adjusted the reg second stage down to 11”wc at the reg test port. About 1”wc per full turn of the adjustment. CW increases, CCW decreases.

It’s a Marshal Excelsior MEGR-253 btw. The manufacturer docs says it’s set at 11”wc from factory which seems incorrect.

Adjusted the reg down to 11”wc at the test port and at the fridge test port. Fridge lit immediately when turned on.

Then lit two stove burners on high and the pressure dropped to 10”wc. A little confused by that drop as the reg should provide adequate flow to maintain set pressure.

So adjusted the reg up to 11.5”wc and tested the fridge again which lit immediately.

The weird oscillation in the stove flame I noted previously is gone.

Based on this troubleshooting the sensitivity of the fridge to pressure setting seems confirmed. The regulator factory set to 13”wc is also confirmed. Our next trip is in a couple of weeks will confirm there are no more 2 am fridge faults.

Thanks again for the advice!

You want a minimum of 11” wc at the fridge with 50% of trailer BTU load in use. In practice I have found that results in a pressure of 11.5 - 12” wc without load. You should be good to go.

[sameo416]

Thanks. Waiting to see the edge case of two burners, furnace and fridge all on.

[sameo416]

And here we go again.

Back out in the woods. In spite of running stable at home after the pressure adjustment as soon as we pulled into our site without power it refused to relight.

Same s—t as before. Multiple attempts required to get it to light (8 this time). The pressure is still 11” at the gas valve.

I’m left concluding this is just a bad unit. Only thing left I can do is to change the control board.

[MVA]

That is quite annoying. Are yo somewhere where it is damper than you have usually had your trailer? I have noted that the frig and w/h can have difficulty when the humidity is high.

[sameo416]

Control board in this model is 3316871.900. Doesn’t seem listed by Dinosaur yet, emailed to ask if there is an equivalent.

Pulled the control board out and discovered the high voltage coil driving the igniter is partly melted and looks like it may have electrical discharge marks (photo). So a new control board is obviously in order, if I can find one.

I’ll send a note to Dometic warranty too.

Wondering now if the issue is inadequate energy in the spark.

[oldwave]

Ouch a crap circuit board I’m sure