Unusual odor/smell 2001 Alero

[Dugfio]

I'm noticing a chemical like odor coming into the vents. After checking and not finding any evidence of any kind of leak, I took it in to the dealer and, of course, they couldn't find anything. Had the starter replaced at that time. After repair, still noticing the odor so I took it back to dealer. I looked along with the technician and could not see any evidence of leaking anywhere. Tech did a pressure test, no evidence of pressure drop. The odor is present in the engine compartment and it seems that the surrounding area is hotter than I'd expect. I thought maybe there is an exhaust leak somewhere but I can't detect anything, no smoke. As expected, when I put the controller in "recirculation" I don't detect any of this. Any ideas or suggestions?