I have an older ('87) class C with a Norcold fridge, it worked fine for a season or so, then began intermittent operation. First glance showed the eyebrow board had solder that had corroded loose, so I replaced that, and it worked. I also replaced the lower board, the thermistor and the patch cable between the two due and it is still showing the problem. The freezer will be 20 or less, while the refrigerator area will be as high as 75. What did I miss? Thanks!