Transworld

I have a B9 A4 and noticed a slight musty smell when I turn the A/C off after it has been running for a while. Does anyone have picture or a detailed description of where the A/C drain is located? I want to go under the car and spray A/C foam cleaner into the evaporator. Or does anyone have a better method? I am also going to replace the cabin filter.

Sjorge3442

I bet your smell goes away when you change the filter. I had a similar issue when I would turn my a/c off after it was running. New filter and boom, all is well.

Transworld

Thank you, I will change the filter first then.

chemengin

Did the filter change work for you? Did you end up using the A/C foam?

Sjorge3442

Figured I'd just add that after swapping my filter back in June, I have yet to have a foul smell appear again.

Transworld

Filter change alone did not work. I had to use the foam.

A4Audi4Fun

Turn the A/C off for the last 2-3 minutes of your drive home; it helps to reduce the amount moisture left sitting in the HVAC piping after you've stopped - the musty smell is caused by mould that can grow in the pipes.