Tiny pieces of material from ventilation system
 

My '91 350 SDL recently began to "spit up" a bit of thin black plastic material out of the various air vents ... can't determine if it is one more than another. Most of the material measures less than 1/64th inch ... a couple of large pieces of more than 1/4 inch, too.

Anyone had this happen?

What is the source of the material? Looks like it might be from a liner for a vent or an air valve flap ...

Nothing else happening in the system.

Insulation from inside the A/C duct :)