RV Repair: Dometic RM2611 Refrigerator, thermo coupler, white flame

Question
My unit is an AC/propane. It runs great on AC however when using the gas it lights the burner and runs good for a few mins. or even longer. Then the check light turns on and the burner is off. I have cleaned the connections on the ground bar and have 12 vdc to the unit. Any thoughts?     Also is there a way to test a thermo coupler with a meter?

Answer
Hi Doug:
The reason for this is one or more of the following. The thermocouple is bad, the thermocouple is not correctly located in the hot part of the flame, the flame is not hot enough, the thermocouple signal is not getting to the control board or the control board is bad. Since the control board is the most expensive of these I would change it last. First thing to do is to to completely clean out the burner tube, compressed air works best. When you are done you should have a nice bright blue flame across the burner grid which is about 3/8 to 1/2 inch high, above that is about 1/16 to 1/8 inch almost white flame and then about 1/2 inch of a redish/purple colored flame. The tip of the thermocouple should sit in the middle of the upper flame. You can bend it in place with a screw driver. While you are there make sure that there is no carbon built up on the tip or any bright spots. If there are scrape them off. Unfortunately a standard volmeter will not register the microamps and microvolts signal produced by the thermocouple. In the years I have been doing this I have only changed one or two thermocouples so odds are you do not have a bad one. They are fairly inexpensive and if everything is ok with the flame I would change the thermocouple first. If that does not fix it change the board, I have changed a couple of hundred of those. Good luck.
Bill