36 in built in GE monogram, side by side model ZISS360DHASS. Temperature set to 1 degree fahrenheit for freezer and 38 for refrigerator. Currently temperature is hovering around 26 in the freezer and 50 in the fridge. I can physically see a mound of ice formed on the top of the fan, water is dripping down on the fan for some reason. I've had several repairs made by technicians, such as evaporator fan, and the evaporator pan replaced. Each of the previous repairs has failed to fix the problem and in fact the same parts were getting replaced repeatedly. Every couple of months the problem returns and I suspect the issue occurs when the fan can no longer function because the ice build up is so bad. It is obviously defrosted when the repair occurs (e.g. fan replacement) so it works for a month or two and then the temperature starts to rise. Note, there doesn't seem to be ice build up on the evaporator itself (though I didn't see the entire evaporator and heater). It looks like water drips down and freezes on the fan eventually causing it to stop. I have a photo but didn't see how I could attach, but I can send if needed. I'm reasonably technical and handy and after spending $2000 in repairs that failed I'd rather try myself as I can't possibly do any worse than those who've tried and failed. When I run the manual diagnostics using the temperature gauges the only obvious message that I get is thermistors 1 and 2 pass, but 3, 4 and 5 fail. I've no idea which number relates to which thermistor, where they are located and whether there really is five thermistors in this model. The thermistor fail message may be a victim of the unidentified root cause or the actual cause but all 3 failed at the same time seems a bit odd. Really hoping someone can nail this issue once and for all so I don't have to replace this one too. This is my second one in 10 years and the other one did the exact same, until we eventually gave in and replaced it, $20,000 over 10 years for two of these is ridiculous, 1 should last 15 - 20 years. Thanks in advance for your help.