I had my basement finished in my old home this past winter. Suddenly there is a mold smell in the furnace room that appears dry. The duct work and furnace are 3 1/2 yrs old. The duct work was cleaned in April. Could it be in the furnace?
Mold growth can take root anywhere that water or humidity occur. If you can not see the mold, it could be virtually anywhere that water could be trapped to form an environment favorable to mold–which includes the furnace, areas behind and between walls, ductwork, vents, crawl space, etc. An experienced mold assessor would be able to pinpoint exactly where the mold is to facilitate remediation. But consider that the mold could be anywhere in your furnace, filter, ducts or somewhere on the route the circulating warmed air.
If you’re in California, you might want to give us a call and see about getting an assessment from Byebyemold.