The air return is open to the wall cavity. Air is being pulled not only from the living area but from the spaces between the drywall and between the ceiling and roof insulation.
We have two problems. One is we have spray foam insulation and we get odors from that. The second is that the vents on the far side of the house do not seem to adequately condition those spaces. Aren't air return ducts only supposed to take air from living areas? If I get someone to close off the air return to the wall cavity, will we notice a significant improvement to our HVAC system?