do you have manual temp control or AETC?
(Pull your blower motor relay (in aux realy box) or fuse 9 in your power dist box (not interior fuse panel) to kill your motor instead of disconnecting battery)
Anyway, your blower motor needs a 12VDC source (provided from your pwr distribution box (always hot btw) via your blower control relay. And a return (to ground) provided via either your Blower motor resistor on manual temp control systems or the control module on Electronic Automatic Temperature Control (EATC) systems.
The Blower control relay has to be stuck closed (or you have a wiring issue) to be providing the source voltage to your blower motor with the ignition off.
BUT you still have to have a return ( to ground) for the motor to go so......
Manual System:
The return comes from the Blower motor resistor or the High speed blower relay. Placing your airflow control switch (max A/C, AC, panel floor etc...) to OFF you will remove the return and your blower motor should stop, if not you have more than one problem component and/or wiring issues.
Now it is possible that BOTH your Blower Motor Relay AND High Speed Blower Relays are stuck closed, then your fan would run at high speed at all times.
These relays are contained in your realy box.
EATC System:
in the EATC system the return is provided by the EATC Module.
I do not have the information on the EATC module handy right now but I suspect you should lose the return for your motor with the airflow switch(max A/C, AC, panel floor etc...) in the OFF position, or you have more than one faulty component and/or wiring issues.
