How to fix a problem with AC, smells bad when it is turned on?

[chooper786]

I have a Ford Expedition 2000 EB.
Everytime the AC is on a bad odor come from the air vents.
But when the AC is not on, but the vent is on there is no smell.
What is the problem and how can I do it myself?
Thank you for your time.

 

[BioHazard]

They sell products at automotive stores specifically designed to spray into your A/C system for this problem. You'll find it next to the A/C recharge stuff.

 

[bushhawg73]

Does it smell like mold or sour water. If so check the drain on the unit. It may be backing up and the insulation inside the unit may be getting wet. Make sure the unit is a little lower on the drain end. You can spray a little bleach water on the insulation to kill the mold, just make sure you rinse it well afterwards.

 

[bonneyman]

You need to get access to the evaporator coil. Typically it's a pain. Since auto A/C's don't have filters like home units, the coils collect everything in the air. Combined with coolness, darkness, and moisture, you get lots of nasty's! Thouorughly clean any crud off of it, but remember the aluminum fins are delicate.
For stubborn odors, I use X-O Odor Neutralizer. Natural citrus oil deodorizer that works like a champ.

 

[luvair]

can use this http://www.autogeek.net/1z-einszett-klima-cleaner-air-freshener.html

once you get the odor fixed, make sure you run the blower without the A/C before shutting of the car. Otherwise over time the condensation in ducks will begin creating a stale odor.