Also, the HVAC is in a part-finished room flanked on either side by crawl spaces. These spaces are dry and I have a fan ventilating out from the HVAC room. However, the walls are made from, I think, dry wall & the whole HVAC room has a bige mold problem. The ceiling is drywall with a layer of insulation above the drywall and below the upstairs floor. This inusulation is very moldy. Best course of action?