blower fan motor continues to operate, after ignition turned off
Normal, as long as it turns off after the engine cools off a little.
I think the poster is referring to HVAC blower motor.
The problem might be from a defective high speed blower motor relay. This relay has constant power supplied to it thru a fusible link. So if the relay sticks the blower will continue to operate even if the ignition switch is turned off.