AC Soot '97 960 Volvo

There is a black "soot" blowing out of my passenger side top air conditioning vent. It appears to be black net lining, maybe from the inside of a hose? It is coming out in small pieces and tiny particles. You can brush it off your clothes very gently, or if you rub it in, it will leave black smudges. Help! I kept thinking it would blow itself out, but it has been several weeks now and seems to be getting worse.