Are you positive the Snip and clip aftermarket Thermister system will work with a Norcold? Remember, your Norcold DOES have a Thermister temp adjustment. The Snip and clip aftermarket replacements are designed for the Dometic Auto temp type refers. So, you have installed an additional adjustable tstat system in conjunction with the existing adjustable tstat system. IMO, that is incompatible. Just go out and purchase the CORRECT Thermister for your Norcold and install as the OEM intended. When I have experienced your type problem, just replacing the Thermister fixes the problem 100 percent of the time(at least 20 times over the years). Also, a defective Thermister will OHM test as good. This is why searching the Internet for a fix, sometimes, does NOT result in a good outcome. Doug