I installed new flexible ducts, an Aprilaire 5000 electronic air cleaner and furnace/ AC in the attic of my house. I immediately noticed an odor any time the fan is running. (The odor seems to be slightly less when the AC runs with the fan.) There is a chemical smell, possibly ozone. In some rooms the odor is minimal and isn't noticable unless I put my nose directly in the stream of air blowing out of the register. In other rooms the smell is stronger. (The worst smelling rooms are also the rooms with the longest runs of duct.) It isn't an unpleasant odor and guests, even relatives and close friends (who like to criticize) haven't mentioned it. I experience mild asthma symptoms, but the rest of my family is fine.
My HVAC contractor insists air from my attic is not getting into the system. At first I was sure the smell must be bad air from the attic contaminating the system. My attic smells dusty and it does get really hot and humid up there, but the odor coming out of my HVAC smells different. (I don't see any signs of smells of mold in the attic.)
What could the odor be?