Dometic refrigerator lighting trouble

[merganser]

The Dometic DM2652 refrigerator in our Forester motorhome has had a problem operating on gas since it was new just over two years ago. When it is called to light it will light and immediately “puff” out repeatedly until it times out and the check light comes on. A second press of the on-off switch will then usually light the unit. This typically happens any time it is called to light, more often when the outdoor temperature is cooler, such as in the middle of the night. It happens at all altitudes we have camped at from 3000 feet to 10,000 feet.


I took it to Camping World while under warranty and was told that because we are in Denver at around 5500 feet, and usually camp higher, the gas side of the unit will not work well. A week after my appointment I took the RV home because they had still not looked at it. I then called Dometic and received a new Hercules control board. I have also taken the gas side apart to make sure all was clean and adjusted, and all contacts were seated. I also checked the gas pressure at the stove, 12 inches at no flow. Still no joy.


This is our third RV and have never had a problem with refrigerators running on gas at altitude. I have run out of things to try. Any ideas?

[SeaDog]

Have you talked to dometic about a high altitude orifice kit. This may help https://bensdiscountsupply.com/domet...refrigerators/ Let the forum know what you find out

[merganser]

Yes, that was my first thought when the problem was discovered. I spoke with Dometic and they told me no other orifice sizes were available or recommended. In fact the operation manual says to run the refer on electric above 5500 feet.



I had searched the internet for different orifice sizes for my model number but was unsuccessful. This one may be worth a try but I will try to find out more technical details about the orifice.

[rockfordroo]

If the board's been replaced, maybe the electrode is funky. The electrode not only lights the gas, but the gas heat provides a very small current through it that the board see's as "gas is lit." Maybe it's lighting the gas, but not providing the feedback to the board that the gas is lit???

Or the 2nd board could be bad, too. Dinosaur boards seem to have good reviews here.

[SeaDog]

Something else to consider is drilling the orifice. There are some charts online that give drill size to orifice size. Start small and test each until something works.

[merganser]

I guess I might order a new electrode. I'm not a fan of the keep buying parts method of troubleshooting but as I say, I'm stumped.


I believe a jet for a higher altitude would have a smaller orifice to match fuel with available oxygen so the drill method would be going the wrong way.

[SeaDog]

Originally Posted by merganser

I guess I might order a new electrode. I'm not a fan of the keep buying parts method of troubleshooting but as I say, I'm stumped.


I believe a jet for a higher altitude would have a smaller orifice to match fuel with available oxygen so the drill method would be going the wrong way.

I gave that some thought after writing is there a way to increase the gap (adjustment) on the air inlets?

[merganser]

Originally Posted by SeaDog

I gave that some thought after writing is there a way to increase the gap (adjustment) on the air inlets?

I have verified that there is sufficient area available around all of the safety covers for air to get to the burner.

[SeaDog]

I was talking about the burner tube where the gas and air mix, if you are sending a mixture that is to rich it may not lite just something to consider.

[wa5tku]

Check to see if the igniter is close enough to the burner so the spark is in the gas when it tries to ignite it. If I remember correctly that is covered in the service manual that you can download on line. Jus search by Mometic and the model number is how I found my copy.

Wes
WA5TKU

[merganser]

Yes, plenty of space around the jet and the igniter distance set to spec.

[merganser]

Here is a link to a comprehensive diagnostic manual that has been posted on the forum before.



https://www.fourwh.com/NewDometicRefrigeratorManual.pdf

[merganser]

Time for an update. I did end up replacing the electrode even though the unit was only about 2 years old with low hours. Just returned from a trip that included off the grid camping at Beartooth Lake campground around 9200 ft. The refer did not cut out and had a bit of trouble lighting but always did and stayed lit. Now the only trouble is that when switching from gas to electric or electric to gas, I usually get a check refer light and have to push the on/off button to reset and that usually works.