OK by flashlight, I pulled the wires from that round device in the bottom side of the flue. I fridge did not respond to the off/on switch with the wires disconnected or with them shorted out. I see from the drawing all the way at top that there is another device above that switch. A thermister? Do I need to check that and how?
If these are not the problem what is left? The circuit board has 12V and the two fuses check out with an ohmmeter. Amazon has a replacement board, should I order one or call the mobile RV guy. I tried the guy we used last time, he is not taking work until after Christmas. But there are a couple of others in the area.
The replacement board is $128 and the rv guys are $100/hr including travel time so the cost is about the same.