1999 Ford Windstar heater/front

The problem is more than likely a broken blend door in the front plenum behind the dash. It is very difficult to fix but can be done. Unfortunately, Ford made this part as one whole plenum unit including the blend door and you have to replace it together. It runs around $400 just for the part. You can verify that it is the problem by removing most of the stuff behind the cup holders and console storage area. When you slide the front blend control lever the door will move from open to closed. It is a common break and when it gets stuck in the summer position, no heat up front. I fixed it myself by taking it to an AC place and evacuating the refrigerant. Next you have to take apart almost the whole dash. It is a booger and takes some time; be careful not to damage the heater core or the AC evaporator. Put in the replacement plenum assembly and put it all back together. You'll have to vacuum the AC system and then recharge. The cheapest price I could find to do it for me was $1200 so I did it myself. Took about 8 hours. Special tools are the AC line breakers and a vacuum pump. The steering wheel will drop down so no need to remove all that. I took both the front seats out and center console out for more work room.