temperature gauge faulty

I have an XL-7 that I bought used from a dealership - since I got it in October its outside temp gauge/clock has not been working - have a snowflake on the gauge, and it flashes and says "-158" and then a minute later its 98 degrees, etc..

messes up the a/c heater/defroster big time and with winter weather you try to get heater to work and it won't work since it thinks its 98 degrees outside..

any one else have this problem?

My guage doesn't even turn on. Is there a fuse somewhere. I looked in the book and it doesn't specify a fuse for the guage.