Interior Temperature Sensor Going Bad?

I have an ’03 6 with the automatic climate control system. Recently my car will not get as hot in cold weather as it used to and the heated seats don’t heat up as much. If I crank the temperature way up it does get warmer, but it seems as though the internal temperature sensor might be going. Has this ever happened to anyone else? It looks easy to replace, but I can’t find the part number anywhere.

Thanks!