AC stinks

literally, it smells like there are gym socks in the vents... is this a thing? is there some sort of flush that needs to be periodically done?

Do you use the air a lot? Do you shut down the car while the ac is still on? Water can condense in the vents/ac system and start to smell if you do. You should turn off the ac for a short while before you turn off the car and let the fan circulate by itself. Not a specific to the A3, can happen to any car.

Change the in cabin air filter first and see if that helps.

just changed the filter, will see if that does it... smells when blowing hot as well, no AC.

St.Hubbins said:

just changed the filter, will see if that does it... smells when blowing hot as well, no AC.

Click to expand...

Yep, I get that occasionally in my Golf. A good spray of fabreeze into the cabin air intake seems to help.

Love your avatar BTW... "this one goes to eleven!"

Love Spinal Tap.

The gym sock smell is microbial growth in the evaporator core.

The only way to get rid of the smell is to kill the microbes, there are sprays commercially available for that express purpose.
The challenge then is twofold:

One) getting the spray to the evaporator core - this is best done by removing the blower fan and spraying directly - not sure if that is an option on a 2011 (never had the dash apart in one).

Two) making sure the smell does not come back.

Evaporator cores are excellent places for mold / spores etc to grow. They get all cold and damp during operation, then usually are left to stay that way for hours after the car is shut off.

As above, the best defense is to run the blower fan on high, with the AC disengaged for a couple minutes before you arrive at your destination. That way, the blower fan dries out all the moisture before you shut the car off.

If the evap core is dried out, the microbes don't multiply and create the smell.

I use Frigi-Clean at my dealership. Works great. It's essentially a flexible hose you shove up the evaporator and spray a shaving cream type foam that gets rid of the bacteria/mildew. Usually gets rid of the smell by the first treatment and the dealership will guarantee the job, usually a year.

The DIY way is to remove cabin filter and spray Lysol everywhere you can. Find the duct the car gets its outside air and spray while the a/c is on high. May have to do it more than a few times but it should work just as good.

the outside air intake is under the wiper cowl. old leaves tend to creep under and hang out there until someone bothers to clean it out. also the "dirty" side of the cabin air filter area accumulates a lot of debris.

I once had a passenger that stepped on dog poo and left bits of it on the duct under the passenger seat. that took a while to isolate.

ugh, that's what i feared - mold spores. need to try the Frigi-Clean stuff, i guess.

replaced cabin filter this morning, and shot my air compressor up in there and down through the vents... definitely improved so far, but the mere thought that we could be breathing in that ****e freaks me out.
need to find a local garage that does that service.

thanks blokes!