I have a 02 Cummins and the heater switch for the floor or defrost will not switch. I have replaced the whole selector console switch and it did not work I've tried some other stuff but would like some more idea's please I do that it is a vacuum switch.

 

have you checked for vacuum leaks under the hood?

95% of the time it is a vacuum leak that causes the blend door to not move off of windshield only.