I have a 2010 f150 xlt ,I have no heat only blows cold, can switch vents, no dual zone, no clicking sounds behind the dash, from what I've gotten from looking it up , seems I have a bad blend door , "controls heat/ac, I've watched videos, most says/show changing it behind the radio, some under the center console and some by the gas pedal.how do I figure out which one I should change, part number 604-252, ty

 

If you do not have the dual zone AC system then the blend door actuator is behind the radio/glove box.
If memory serves you lower the glovebox, remove the radio and there are three screws that hold the actuator in place.