Did the same thing just today
We had the same problem in our 06 Sorento. Turns out a squirrel appears to have started an acorn collection in our blower. Wife had been complaining for a while that the blower had gotten really loud recently. At first I brushed it as my blond wife but after hearing it first had I figured it was either the blower motor or something had a nest. Weird thing though, you would have though you would hear ratteling or something with the acorns but we didn't. Just a loud vibrating humm the faster you turned the fan speed.
Anywho,
Simple fix. Four phillip screws and a unplug/replug.... all done. Should be able to get this in no time w/out removing any other components. BTW located passenger side, below the dash.