I have a 1998 Accord, and recently I quit gettting airflow from the defrost and dash vents. There is good flow to the floor and manual side vents. I replace the cabin filters, and the problem persists. Does anyone have any idea what the problem could be--perhaps the selector motor?? If so, is this an easy DIY--I had no problem replacing the cabin filters, but I would say that is the limit of my skills..

Thanks!