outside temperature

About a week ago on my 2002 Astro, my outside temperature on my overhead console started giving me wishful readings. Like if it's 28 degrees outside, it will show that it's 45 degrees. It was working fine until last week. Can anyone tell me if there is a sensor I can check or clean or something. If there is a sensor where would it be??? It's very frustrating having the wrong temperature staring me in the face.
Thanks!

The sensor is located on the hood latch support, just in front of the radiator, (or condensor if equipped with air conditioning). The sensor is available only through a GM dealer.

Thanks! I will check it today. Could it read an incorrect temperature from being dirty or is there a way to test it before replacing it?