91 Vette Blower Moter not turning off....

Can anyone tell me what could cause the heater/ac blower motor to not stop? i had to disconnect the power to the blower to make it shut off....please help!!!

I fixed the same problem on a Cadillac.
Need to trace the wires from the blower motor and see if they lead to a module of some sort.
I'm guessing that the fan control module has an internal short (if it has one). Or better yet, call a dealer and ask the parts guy if he shows a listing for one.

Hope this helps.