You are experiencing a very, very common issue and complaint. There are a variety of suggested remedies. Some suggest turning off the a/c about a mile before you stop so that the moisture evaporates. It is believed that the condensation causes mildew and that is what causes the smell. Some have had some luck with their dealers using a Lysol product to spray into the system to kill the mildew. Somewhere out on the Internet is a dealer TSB on the issue. It is generally not covered under warranty.

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