I understand the tool, I have a similar one from NAPA that works, and there are several at work, I use them to estimate temperatures on plastic sheet for thermoforming. This particular one before its untimely death was "wonky" It was purchased to attempt to track down an overheating issue in his F150, but it seemed as if for every three times you took the same temps you'd get three different readings, and you essentially had to guess if you were accurate enough. For instance, top radiator hose, you'd get 60F, 110F, 180 F. Then you'd feel the tube hose with your hand and go, that feels like a 110 to me. If you did this enough a pattern would emerge. The window thing was stupid, but then again, I would not expect sun in the northern states to cook a display to the temp degree of failure of the display. As other electronic displays such as radios do not seem to have the same problem.