Blower motor sticks on high speed

I have a 2003 2500 6.0 liter Savana, the blower motor twice now has switched to high speed even though the control is on low speed. The first time it happened my wife turned the speed switch from high to low about 5 times, then it went back to low speed and seemed to function fine.

Today it did the same thing, but would not drop out of high speed. It even kept going with engine off and key out. after about 15 min and multiple on off it and fan speed adjustment, it finally worked.

Does this sound like a resistor/relay?

Steve

could be a stuck relay but it's strange that it stays on even with the key off.

Fan stuck on again,
Anyone have any similar experience or help?

Had similar problems with my Chevy van and it was that shitty resister. Had similar problem with many ford vans and it was always the shitty switch.