Outside Temperature

[97 Ivory Pearl VIII]

Recently, the outside temperature display function on my '99 Navigator has been acting up. A few days ago, it displayed 47 degrees all day, long after the temp rose higher than 47 degrees. Later in the day it finally started displaying the correct temp. It didn't start up again until Friday. Again, long after the outside temp climbed past 57 degrees, it still displayed 57 degrees.

Does anyone know how to troubleshoot this problem? If I have to replace the outside sensor, where is it located? How expensive is the part?

Even though my Navi is 9 years old, it only has 67K on it. this is the first problem I've had with it since I bought it this past January.

Thanks in advance for the help. You guys always come up with the answers!