When I bought my current turkey - uh sorry - car, the A/C smelled like a moose with very bad breath. Mildew +. I used Wynn's Fresh Air (Air Conditioning and Heating System Odor Treatment). It smells pretty bad too, but when THAT odor finally went away, the result was pretty good. The mold seems to have all died and I've only used one additional shot in the last 3 years. Hope this helps.