I have an A4 since 2014 and I have had this foul smell when I turn the A/C on. This started happening after a year or so. The Audi Dealership service people told me that when a/c turns off there is some residue left and it stays there. Next time you turn the a/c on it remits this foul smell which is hard to bear.

They said they know about this issue and it will cost about $300 to clean that area, which is ridiculous. Why would a luxury car maker have such an issue in the first place. I have cars from other brands and never experienced this.

Any tips/suggestions on how to get rid of that smell?

Hello, 

Has the pollen/cabin filter been changed on this since new? 

This appears to be a fairly common problem and relatively easily sorted by a cleaning and spraying- into- air-duct procedure. I'm sure you will find this in detail  via. a  Google search, but worth getting the flier change if not already done so.

Kind regards,

Gareth.

As Gareth has stated, there are cleaners available that are like a smoke grenade that you let off inside the car with the windows closed and the air con on full (recirculation mode) for a few minutes...it then gets all around the pipework and kills of bugs and stuff (sorry, not a biologist) that create the smell.

Thank you Garret and Trevor. Has the filter has been changed. As per the service dept. at the Audi dealership I go to, there is typically a residual fluid when a/c is used. This area is hard to reach and its recommended that a professional should clean it up. The other solution they recommended was to leave the fan running without a/c for about 5 minutes before i turn off the engine. 

I will try the smoke grenade type cleaners if that helps.

Hello,

Not sure what your answer is whether the cabin filter has been changed or not. If it were mine, I would ensure this is changed before you set about your cleaning routine. Strange things cabin/ pollen filters and scheduled changes. My experience at main dealers included getting a quote for the due service then asking if that price included a new cabin filter. Generally no! That will be £X more. 

Even when changed, it seemed to get very dirty in the following year! - if you see what I mean. Generally not a difficult job and worth doing it yourself for peace of mind- for Clifornia I guess every year.

Kind regards,

Gareth. 

I meant to say, Yes the cabin filter has been changed. I think my car is due for next service soon, I will definitely confirm with them if they are putting in a new cabin filter.

Personally I would be ordering a new filter and putting it in myself as part of the treatment. You will know it's been done then. 

Kind regards,

Gareth.

I have similar problem . So far i did 

- replaced pollen filter x2 

- desinfected the system using of the shelf products 2 times , one foam spray directly in to airvents, second spray can left for 30 min with closed air circulation 

- cleaned up air intake under the plastic located where wipper motor is 

Still get dust/mouldy faul smell when i turn the air con of for about 30 seconds 

Any ideas ?