I need to correct myself there is no resistor on a auto ac system from Ford. It is either the blower motor speed control(Ford base part# 19e624) or the head unit(Ford base Part# is 19980). The very bottom pick is a blower motor resister for a manual ac system. I believe you can only get the part you need, is from a dealer. The only thing behind the dash is the blend door module which opens and closes the door for hot and cold air. The part you need is known as a blower motor speed control(Ford's base part number19e624). There is a chance that the actual ac unit head is bad.