The ambient temp reading inaccurate.

It goes blank. I just ran an experiment. The sensor read 83 in my garage. I then put an ice bag on the sensor at 3:38PM and got the following readings: 3:38 83 3:42 68 3:35 60 3:46 57 3:48 53 3:50 47 Pulled Ice bag off Drove around and ran an errand till 4:15. The temp never changed from 47. The outside temperature is 86.

I ran another experiment. I Cooled down the sensor that was on the car to 49 degrees. I then swapped out the sensors to one that was at room temperature (about 70). When I plugged in the room temperature sensor, the display still said 49 degrees! Where in the car is this number being held? And why is it not updating to the reading that is being sent to it by the sensor?

Sounds like a good possibility. Is there a part number? Is it in the 'too hard' pile? I'm not sure what else on that display would be controlled by same chip but other numbers (MPG, Gallons to empty, etc) all seem OK.