Volvo Repair: dahboars shakes when AC is on 3 or higher setting, crystal ball, cold air

Question
ac blows cold air out fine but on 3 or higher something insidethe dashboard shakes and vibrates loudly. The AUTO setting does nothing now - whereas before it ran the ac on high.
I was hoping I could have an idea of what might be causing before I take into a mechanic.

Answer
jon, depends on what model you have.  I will assume a 960 since you didnt tell me so I will look into my crystal ball and guess.  960 it is.  Most likely you sucked a bag into the fan.  You can put your hand in the hole and feel around and see if there is something in there.  Common problem.  Let me know what you find.  Roger