1996 Bonneville A/C- heater controls

My wife has a 1996 Bonneville and the heater contols are starting to act funny. The outside temp is showing 164 degrees. It take a bit to shift modes and now the heater doesn't work. Any help would be appreciated.
I hear that maybe there is a computer,but I don't know where to look.

Bobby

you have a bad outside TEMP SWITCH IT IS LOCATED OUT SIDE BY RADIATOR. IT COSTS APPROX 35.00 FROM DEALER AND REAL EASY TO INSTALL