I have a new home. Just built, 6 months old. We have had our ac running for a couple of weeks now, and we are having the smell of the attic coming through our vents. The air that comes out of our vents smell the same way the attic smells. It smells like insulation and that attic smell. We have a dual unit. One in the attic and one in the basement. No smell from the downstairs vents, only from the upstairs. I have small children in the house and the smell on the second floor is awful. The builder say the smell is nothing harmful, and the HVAC guys are coming out on Wednesday to take a look. Wonder if anyone else has experienced this and what did you do? I am so frustrated and I am looking for any advise.

Its possible that the return could be loose and the fan is pulling in air from the attic and blowing it into your living area, hopefull the hvac tech fill find and repair