My windshield wipers do not park all the way down. The left one is up at a 5 degree incline, the right one more like 15 or 20 degrees. I went through a car wash today, and the air dryer blew them all the way to the left, and back to the right a little. I turned them on and back off, and they returned to the original position (5 and 15 degrees). Car is 2002 Grand Marquis LS.
The problem might be that the wiper arm splines are stripped out and slipping on the wiper drive posts.
Look where the wiper arms pivot and there should be a cover that exposes the wiper arm mounting nuts. Remove the wiper arm mounting nuts and remove the wiper arms. Inspect the splines in the wiper arms where they mount to the wiper drive posts. If the splines in the wiper arms are stripped out replace the wiper arms.
As usual, I agree with Tester.
As to the cause of stripped splines, this is usually due to drivers who fail to clear snow from their windshield prior to turning on the wipers. If this describes the OP (or anyone else who drives the car), at least you know who to blame.
And–just for the record–ALWAYS clear heavy snow from the windshield before starting your engine.
If they are not stripped out they may just need to be repositioned. They may have been removed for some reason at one time (windshield replacement?) and not put back on properly. I recently changed my wiper arms on my Taurus and had a similar problem until I removed them & put them back on in the proper position. On my car it was just a nut on each side, but you may need a puller tool for yours.