Based on what I have read regarding potential issues with smelly ac units, I requested my dealer to enable the after blow function on the HVAC unit. The service advisor told me today, that I was the first person ever to request this from their service department for my vehicle. When they attempted to turn this on in my vehicle, they were unable to do so without the help of GM. Maybe I'm being too paranoid even though I live on the dry west coast. But after reading about other people's experiences, I thought this was a good preventative measure to take.