run ro/di water tthough the air vent. Then look up some diy silencers for the vent, basically it is a pvc pipe, maybe 1-1/4 inch with caps on each end, drill a hole in each end, and shove th silencer over the air vent so the tube sticks into the silencer about 2 inches, then stick another tube into the other end of the silencer... That should do it...
Good luck
Bill