ac, heat vents not opening

Fusion 2010; sometimes the heat and ac vents go partially or to near fully closed, This may happen at anytime and the condition goes away at random. The closing sometimes lasts for 15-20 or as few as 5 mins. I have not been able to make this happen by playing with vents or can not make the condition go away by stopping and restarting car. Going to the dealer in hopes they have solved this problem before. Fan is running can tell by sound or when partially closed air flow is still present. This may not happen for months and then a few times for a month or so.

Updatebrought the car to the dealer for a whinng noise on the engine, idler pulley, found out there is sevice bulletin on the vents need to recalibrate via computer.