I recently had my ac cleaned after noticing a variety of bad odors coming from it for a few months. The odors were present when the fan was on (vent closed) and also were seeping through the front fins when the unit was off (vent closed). It was disgusting and nauseating and got worse over the course of three months. Ive tried air fresheners which only mask the smell and a quality air purifier which didn't do anything. Vinegar and baking soda together have worked to combat these smells but with time. For now, Ive covered it with a plastic bag and put vinegar and baking soda in the room. The smells appear throughout the day anywhere from late morning to 7pm, to midnite to the middle of the night, waking me up. I live in a very hot, desert climate. One possibility might be mold but the fact one of the odors was fast food has me thinking its just very poor outside air so I'm asking the community: 1. Are these odors likely from the outside air only? 2. Are there any window acs that do NOT use outside air to dehumidify? Thank you for your time and any input.

What did the cleaning consist of? Most window ACs get mold. The condensation sits in the tray, and the tray has a tiny lip of height, and if the tray isn't tipped downward slightly, it gets moldy very fast. Even if it is tipped, dead insects and dirt can hang onto water or clog the small opening on the edges of the tray.
Another possibility is a small dead animal deep in the workings, which it might be if the smell is really disgusting.
As for food - who knows? Any children near it?

http://www.daviddarling.info/images/air_conditioner.jpg

Thanks for your reply. They cleaned it with detergent warm water and bleach. I cleaned it too myself back in December. Yet the smell remained. When they took the ac out to clean there was just a lot of dirt/sand in the tray, very little if any water. After unsealing my windows last night, I did smell the odor through there too and convinced its just the outside air, not anything dead or mold. I might just live in that foul of a neighborhood.

Thanks for your reply. They cleaned it with detergent warm water and bleach. I cleaned it too myself back in December. Yet the smell remained. When they took the ac out to clean there was just a lot of dirt/sand in the tray, very little if any water. After unsealing my windows last night, I did smell the odor through there too and convinced its just the outside air, not anything dead or mold. I might just live in that foul of a neighborhood. No children are near the air conditioner.