There was more. While spraying the cleaner on the coil, the brother told me how he had cleaned the coil last year with a pressure washer. The inspection of the plenum in the crawl space indicated that a flood had occured in the laundry (furnace room). The nylon mesh that had held the insulation in place was torn loose by the weight of the wet insulation. Hmmm, do you think that maybe the pressure wash session and the flooded insulation could be related?