It is on the side where the battery is.
http://www.audizine.com/forum/showth...ilter+location

Just replaced my cabin filter.

part is only 25 bucks, labour is 10 bucks.

itz best to replace it at least once a year.

Ok cool. It was exactly where I thought it was. Just someone on here threw me off in another post by saying it was on the other side of the glove compartment. I just bought AUDI Cabin Air Filter today... Going to install tomorrow morning on my 3.0 before my girl takes it to work. Thanks

There is another thing you can try. You put your heat up on high and take out the cabin filter (Cover your vents with paper towels) and run it for like ten minutes. While running you spray this a/c stuff you can get at an autoparts store in there a few times. Sometimes bacteria and/or other crap can form in your vents. I changed my filter and did this with much success.

Ok guys, I changed the CARBIN AIR FILTER like at midnight last night because I was bored and wide awake. If anyone needs pix to DIY please let me know. It was super easy... Fixed the smell instantly

If the air hasn't been used for a few months it is stale water/dust in the evaporator and pan. Smells like stale dirty socks and goes away in a few minutes. Changing the cab filter could help you some. Like said in earlier post, make sure the drain is open. You should see water dripping from the passenger side/underside ofthe car when the air has been in use for awhile.

Just post that DIY in a DIY section, maybe it is gonna help someone.

hey R3K8...

just wondering, did you ever solve the issue with the bad a/c smell? because i am now just experiencing what you went thru. mine also lasts for the first few seconds and then that stale smell goes away.

was it the cabin air filter you changed that fixed it? and if so... did u buy the one that was charcoal lined or non?
does anyone know here if there is a big difference in getting the charcoal lined filter or is that just a gimmick?

cabin air filter did the trick for me.
it got rid of the "rotten fish in a cottage cheese filled diaper" smell.
swapped it out in the advanced auto parking lot...

but buy it on ecs.com. waaay cheaper than a parts store.

thats quite the scent you had there! ha.
i tried the sight you recommended but it didnt come up. r u sure its "ecs.com"?