Norcold refrigerator

Thanks for all the info. Will take it apart and try cleaning everything.

Take a blow gun and clean all the debris out of the burner tube. Might fix the problem. I've had the same thing happen and cleaning it made it work again. Now I do it every spring.

Dirty and or restricted burner. Rust and junk from the boiler tube may have fallen down from the boiler tube interior and may be fouling the burner along with the ignition and flame recognition process. Take the little tin cover off that encases the burner and if covered with rust flakes use a vacuum to clean them up. Don't let them crumble and fall into the burner. If they do then ,the burner will have to be disassembled and cleaned.

If the above described is your problem after cleaning the burner securely cover it. Go to the roof and remove the fridge vent cap and carefully remove the screen from the vent. Remove the wire and swirl shaped baffle from the boiler tube. If you have a 10 gage shotgun brush (few of us do anymore so use a 12 gage)and clean the remaining flakes of rust out of the boiler tube.

On most Norcolds the ignitor is the flame sensor. For $13 I'd try that plus it's good to have a spare it that does not do it. I would clean the area around the flame before doing anything else.

One of three things,
First, bad flame sensor.
Second, loss of control voltage.
Third, bad control board.
These things are very simple devices, so it is likely going to be one of the above.