TXaudiTX

I have 16000 miles on my 2003 Audi A4 and it recently started to smell really bad when i first turn the AC on. Anyone else have this problem and any possible solutions?

yourk

go to dealer.

USP

maybe a dead rat or something. I remember someone else here having rats in his engine bay.

A4TDIQuattro

I had this exact same problem. I tried most odor removal chemicals squirted through the blower side of the evaporator.
Airsept, Wurth, Comma, air bomb,
Nothing removed the smell.... Then... I removed the center vents. They just pop out and squirted some foaming upholstery cleaner with mould guard down there. It foamed upstream of the evaporator and no problems since (8 months)

5am

Did you use the whole canister and was it sprayed with the vent running on blower mode (if so, at any particular speed?)

I have had the prob for over a year and resorted to just not turning on the vents and having the windows open - a shame in a car worth thousands that it smells so awful.

Halo549

You need to replace the cabin air filters. And clean the cabin air filter socket. Try using the fabreeze cabin air filters?