AC bad smell

I have a problem with my '02 Ford Windstar. The AC blows bad smell when I turn on the engine, what would it be the cause of this problem?

Edgardo

I would start with a new cabin filter!

Open the hood and look on the plastic wiper cowl on the passenger side. Remove that panel and change it.

If you change the cabin air filter and still have the problem, you're looking at bacteria and mold growing in the evaporator. Common problem with all vehicles today. Try this stuff

http://www.airsept.com/index.php?loadmod=ac