I had the same problem. I decided to change the upper temperature sensor based on a recommendation from another website. I was able to get the part for under $10 from McCombs Supply in Lancaster, PA. I saw a YouTube video on how to change the sensor. When I did the work I found that the top end of the sensor was covered with a black tar substance that appeared to have oozed down from above. This substance may have caused the problem since the sensor was not clean so it would not be sensing properly. Perhaps the substance softened up during transport from China? I just changed out the part yesterday so I don’t know if the problem is actually fixed. Just wanted to make the community aware of the black substance that could be interfering with proper upper cabinet temperature sensing.