2008 Mercury Sable windshield fugs up

Try pulling fuse 15 & 37 from fuse panel for 60 seconds with key on. That may reset the actuator then reinstall them. If not it may be the actuator is bad and not moveing to the defrost side. A pro may have to scan your car to see if the heater control is sending power to it. It also could be the door has broken off the shaft. To see it you need to pull the cluster as well as a few panels below steering column.