I have a Volvo 2007 S60 2T. I have noticed that sometimes the air conditioning blower is on (apparently for hours at a time) after returning to the car. The car is turned off and the ignition key has been removed when this happens. It does not happen all the time. Is this normal.
The A/C blower in the passenger cabin, or the electric radiator fan under the hood? The electric radiator fan under the hood is normal on some cars, but they normally shut off after 10 mins or less to reduce coolant temps. Any more than that, and you should go in for warranty service. In the passenger cabin is not right, and you should take it in for warranty service.
I agree that something is very much amiss with this car. As BK said, the radiator fans will normally run for only a few minutes after the engine is shut off (and only if the engine is very hot), and the fan that supplies air to the cabin should never be running if the engine is shut off.
Since this defect will very shortly kill the battery, I strongly suggest that the OP take it to the Volvo dealer a.s.a.p. for warranty repair.
I have not witnessed it myself, but I read somewhere that my Volvo S80 will start the A/C blower after the car is parked and run it for a while to remove moisture build up in the evaporator. This is one way of reducing mildew in the A/C system.
The dealer can probably tell you for sure about this.
What markmast said could be true. It could also be an aftermarket system installed by a previous owner if you bought the car used. Some manufacturers, Ford and Saturn that I know of, had controllers and wiring harnesses that they added on when people complained of odors. Ask the dealer if there is nothing in the owner manual. If you bought the car used, have someone check for and aftermarket afterblow module. That said, none of these systems should be operating the blower for HOURS continuously. The blower draws too much current, maybe 10 to 20 amps. They blow for a short time or pulse. Sometimes they are designed to start the afterblow after a time delay that allows the AC evaporator to warm up.
The only aftermarket unit that I know of is marketed by Airsept. They have lots of details on their web site.