Hi everyone, hope you'll can give me some insight.
Our plenum box is approx 37 years old it is insulated inside with some type of black compressed insulation. The problem is that anytime the A/C or Heater come on it will blow some pepper like debris out one of the air duct vent, that air duct is the shortest and closest one to the plenum box so it seems that its the one that gets to blow out that debris, which lands on the furniture directly underneath the vent. The debris looks like black dirt or pepper and when you pick up a piece you can smear it like if it was charcoal.
Is the insulation disintegrating? Is it possible that this so called black insulation inside the plenum box contains asbestos??
The air ducts connected to it are all sheet metal and covered with insulation but they seem to be intact and not damaged..........
We are thinking of replacing the box to see if it resovles the issue.
I am worried that this whole time its been blowing out asbestos fiber . Any thoughts on this? Thank in advance!