Why is my blower is irrational and continues to run after car is shut off

possible stuck blower motor relay,or blower motor resistor may be bad.check the resistor first,for being burnt,also the resistor connector!post findings.

The blower speed control is most likely a 'in series' solid state regulator, which when it shorts it allows power to be directly applied to the blower. When they go bad they can either short or open and then the blower won't work at all except perhaps at full speed, where power bypasses the regulator.