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Front Blower problem on 2001 Expedition

Today when came home from a short drive (3 miles or so) I parked the car and the turned the engine off. When I did that the front fan blower motor went to high. Key can be out of the ignition and fan keeps running at max speed. Start the car back up and everything is normal including all fan/ac/heat controls. When I pull the front fan blower fuse (Fuse 105) the fan stops. What’s wrong? I have done general searches online and not been able to find anything relevant. It’s a 4.6L Eddie Bauer. White… but I don’t think that matters.

Just guessing, but it could be the blower relay. I had a similar problem on my 2008 Hyundai Elantra. I went to the dealer today for other service, and mentioned this. What would happen is that even though the dial is in the off position, the blower would turn on. At first, they couldn’t find anything, but after the tech got done with the service, he gets in, starts it up, and starts to back out, when the blower comes on, even though the dial was in the off position.

Your HVAC system may have a solid state blower speed controller. If you have a variable speed control instead of several fixed speeds then you have one. When they fail they can short and supply full voltage to the blower motor.