Where is my climate control unit?

I have a 98 Mercury Mountaineer AWD who's climate control quit working. It doesn't change states (defrost, floor, dash, ect) or temperature, I can only change the fan speed. I've switched fuses and got no results. My next thought is to change out the control unit but, I'm not sure where it is. Is it housed behind the switches? Possibly on the back of the switch cluster itself? Maybe in a different area of the dash altogether? Could it be something other than the control unit? Any input would be valuable.