[Mikendebbie]

I don't remember a thread on that topic - but there is always a first I suppose.
I cleaned my AC filters this week and noticed a few bits of sawdust on the top side. I had never seen sawdust on them before. I was up on the roof washing it 2 weeks ago and maybe I jarred some dust loose.

If you can post of pic of the black spots and maybe pinpoint the location you found them - it might help identify what they might be.