Sorry so long to respond. The unit is an electric heat pump system. 3 Ton. The home is only about 3 years old. There was no other unusual factors present. When I did the inspection, there was no particles or black soot like material. This has occurred about three weeks after I did the inspection. The people were present at the inspection and agreed that this was not present when we did the job. I just would like to try and direct them. I offered to go back and look at it with them again to see if there is anything else going on now. Since the home is relatively new, I really do not know what this could be from.
