Blower motor will not turn off..91 Eldo

Help....Had the vehicle parked with no problem, started and ran maybe 5 minutes, turned off ign. and blower continued to run at high speed. Opened door to turn off radio...blower continued to run, with ign off, key out....walked away from the veh. and returned in an hour to find blower still running. Looked at the meager wiring diags I have and unplugged the feedback wire going into the blower. With the wire out I have no blower at all. A/C will still come on but I have to drive real fast to get any air flow thru it.....IDEAS