I was thinking the ignition switch may be bad, but if you have no control over the speed, it sounds more like a problem with switch. Check to see if the fan stops if you disconnect the switch. If it does, the problem is before the switch. If it doesn't, my guess is you have a ground to power after the switch itself.
Let me know what you find.
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Tuesday, April 17th, 2012 AT 1:34 AM