My Grand Marquis has a problem with the vent system it. It will cycle between the vent positions continuously. It will stay on one position for anywhere’s from 5 seconds to a couple of minutes. It seems to like the defrost position the best and stays there longer. Does anybody have a clue as to what might cause this?

 

Sounds like a blendor motor may be going bad.

 

Oh no, not a blender motor, don't tell Jimmy Buffet, no frozen margritas