We have recently purchased a used travel trailer with a Dometic fridge that probably hasn't been lit with gas for quite a long time. Works fine on electric, but when we try to switch to gas, it won't stay lit. We purged air from the lines and have done a rudimentary cleaning of the flue baffle and burner. The spark-lighter successfully ignites a flame over the burner tube, which is clear blue over the slots, but as soon as the igniter stops, the flame goes right out. We have turned it off and on and tried multiple times with the same results. Can anyone suggest what might be the problem?

It's the flame sensor that "should" keep the flame lit. A very small voltage is generated from that flame sensor. No voltage, no flame.

Christy, Just saw this was Post Number One. WELCOME! Hope we can help you and you'll hang around to help others. Thanks for posting Make/Model. Many do not and it really becomes a guessing game.Our friend and mentor Chris Bryant (RV Shop Owner) has a lot of manuals on his website. I picked this one because I couldn't find your model number and this one was close to it. Your problem sounds somewhat like "thermocouple" in the troubleshooting but the ones I've seen do that will burn a few seconds after lighting and sparking stops. The it'll do a "re-start" since the thermostat is still calling for cooling, and repeat the cycle. If you DO replace the thermocouple that "wrench" fitting is NOT LP Gas. It's only an electrical connector so don't overtighten. But that's just a warning for futures, we aren't anywhere near that far along yet.Robt, the manual I referenced says "thermocouple" and not "flame sensor, flame prover" etc. I don't fully understand the "sensor" but I do know that a failed thermocouple will let the gas valve flop shut once the logic board's power is removed from it after the startup cycle. Christy should be hearing a CLUNK when the flame goes out since the Valve isn't getting the voltage from the TC that it needs to stay open.Chris, Does one of your online service manuals cover Christy's model RM2351? If so which one...

Hmmm... Thank you both so much for responding. I'll take a look at that manual and see what I can find. Also, locate the flame sensor. Is that something I can test myself?

Also, are the thermocouple and flame sensor the same thing?

Depending on model year (serial numbers) the Dometic RM2351 used a 'thermocouple' and later model year uses a spark electrode (which is the flame sensor).Your main flame is lighting off (good spark) but won't stay lite because circuit board is not getting the flame proof signal....either bad sensor (likely) or bad circuit on board Dometic thermocouple....part #2932052018.......LINKDometic spark electrode....part #2932781012.....LINKBefore replacing....pull thermocouple/spark electrode (whichever one you have) clean the connection at board...make sure it's tight and clean up thermocouple. Spark electrode gap should be 1/8" and both need to be engulfed in main flame.

Dometic RM2351 Refrigerator not lighting with gas

Christy_T_
Explorer
Jun 24, 2014
Hooray! At last, we have a cold refrigerator working off of gas! We just ordered a flame sensor and a control board and put them both in and now it's working fine. Don't know which one was actually bad, but they're both good now. Thank you all for the advice and support. It was greatly appreciated!
j-d
Explorer II
Jun 10, 2014
Flame Sensor Theory of Operation link I mentioned. The sites I searched emphasized they are info and discussion not DIY. Their theme is "If you are not a professional, call one."
j-d
Explorer II
Jun 10, 2014
I looked at manual above and it mentions only Thermocouple, which is the Two-Wire device pictured above. Diagrams in the above manual show a Two-Wire device, which is a Thermocouple. If Christy found a single-wire sensor, it doesn't seem to be covered in the manual. I looked up how a Flame Sensor works and it's pretty involved. Different ionization rates because the Burner Surface and the Flame Sensor have significantly different surface areas. The flame therefore causes an uneven flow of AC current. Blah Blah Blah. Testing sounds tricky. I think what I'd do is clean the Sensor, its Connection, the top of the Burner, and the joint were the Burner grounds to the rest of the Fridge. I can link the article I found if you like.
hhornig
Explorer
Jun 10, 2014
Here is the service manual for your unit. It appears that you need to measure resistance between the electrode and ground.

http://www.nancyemmert.com/region6/Resources/NewDometicRefrigeratorManual.pdf
hhornig
Explorer
Jun 10, 2014
Here is the service manual for your unit. It appears that you need to measure resistance between the electrode and ground.

http://www.nancyemmert.com/region6/Resources/NewDometicRefrigeratorManual.pdf
hhornig
Explorer
Jun 10, 2014
I am not familiar with that sensor, but you would normally connect the red lead of the multimeter to the wire and the black lead to the piece that attaches it to the frame (ground). I will see if I can find what reading you should get. I would not leave it attached to the control panel while heating it in a flame.
Christy_T_
Explorer
Jun 08, 2014
We definitely have a "one-wire" flame sensor. I'm not clear on how this process of checking it with the multimeter looks. Its' connection at the control panel looked clean and good. So, I leave it connected to the control panel, hold its' tip in a gas flame (generated by what?), then I don't know where to place the leads from the meter. Thanks for your patience. This is new territory for me!
j-d
Explorer II
Jun 08, 2014
Just found pix of both the Sensor and the TC on Amazon.
Flame Sensor:
Porcelain Insulator, ONE Wire Connector
Thermocouple:
Made of Brass with a few inches of Copper Tubing, then TWO Single-Wire Connectors
Again, which do you have?
j-d
Explorer II
Jun 08, 2014
The Meter's Test Leads are the two coiled wires in the photo. Red to POS, Black to COM. Third socket in meter not usually used. The "Leads" on the Spark Electrode would be the wires that connect the device to the rest of the fridge, at whatever part that happens to be.
Did you figure out if you have a Flame Sensor or a Thermocouple? OB, above, is rarely wrong. His post says your fridge Serial Number will tell you which device you have.
Christy_T_
Explorer
Jun 08, 2014
Trying to test the spark electrode with the multimeter. Can anyone tell me what the "leads" are?

Forum Discussion

Dometic RM2351 Refrigerator not lighting with gas

About Technical Issues

Related Content

Dometic refrigerator

Dometic Refrigerator

Dometic Refrigerator cooling

Refrigerator quit working

Dometic RM2652 refrigerator dead