I have a 03 dodge grand caravan sport and the heat/air will only work on defrost no other setting. why?

I have check the resistor and fuse for the front blower motor. Nothing is wrong with the rear. When we went to replace the blower motor we realized it was fine. On the bottom of the housing something is connected. When I touched this my heat went directly to my defrost and will work in any setting. However the heat will not work in any other setting ie: floor, multi.