Your high temp is higher than mine which is 138. You must have something different than the readings that I have seen You have a very large swing from the low to the high. I wonder if it is going from a very chilled to the high. My avg shift is only 18 (120) degree and low is 33 (105) less. You have a swing from 84 to 140 that is 56 degrees something sound out of the ordinary. The only time I have ever seen my low temp similar to yours was in the 1st few days that I had it.