I possess a possessed 2002 V70 Station Wagon whose “after blower” cabin fan comes roaring on up to two hours after the car has been turned off, key removed, garage door shut. And, no, the exorcism didn’t seem to work. Don’t know how long it’s been on or when it was planning to turn off.
Read your owner’s manual. My S80’s fan comes on after about 45 minutes to an hour and runs for 5-10 minutes, sometimes more. It is supposed to remove any condensation from the AC system, as I recall. Yours may be different, but that’s how mine works.
My 2001 V70 Crosscountry does the same thing. Usually on hot days after it has been parked for a while. The internal fan runs for about 10 minutes and shuts off… I guess it is normal.