Smells problem
2007 Chevy Monte Carlo V8 Front Wheel Drive Automatic 16000 miles

there is a really sour smell coming from the air vents especially when using outside air setting. dealer has stated he sprayed some sort of chemical coating thru out the system to kill any mold/mildew and prevent future build up. also adjusted fan settings so that fan runs even if car is turned off. cabin filter was changed last summer when smell first noticed. smell was not as obvious during winter. obviously no dead rodents as this started last summer. Next step is taking the whole system apart including dash, ducts, coils, etc... Also, there is never any water pooling on ground after using air conditioning. I find that quite odd but no one seems to listen. Car is kept in garage at home and work. Any other ideas??