milkyjoe01

I have the dreaded musty, moldy, cat pee smell emanating from my AC/heater system in my 2004 Audi A3 & it's getting worse. It's the dual zone auto climate control system. I replaced the pollen filter with an activated charcoal filter 2 days ago, the previous 1 was a standard pollen/cabin filter. I think it's the start of bacteria. It's the smell of flowers that are over a week old.What is strange is that i have no water ingress anywhere!! I have had the car 2 months & with it being the end of summer & wanting to be a skinflint & save fuel i rarely turned on the HVAC & when i did i used the ECON button so as not to activate the compressor thus leaving the AC off but then the colder weather started & i start using the heater but still on ECON, when i started to notice the smell, only just, it was very mild. Checked everywhere for signs of water but nothing, no sloshing noise like what i've read in forums, nothing so i carried on using it but after reading that over use of the ECON button can lead to AC smell i started to use the HVAC with ECON off & the smell gradually got worse. I want to use an air cleaner bomb but i'm unsure as to where the recirculation air intake is. I know on diagrams the intake flap is right behind the glovebox but i was thinking there maybe ducting attached to that which draws air in from the cabin at some other point so i have waited until i can direct the air bomb directly at the recirc air intake if i cannot find the intake then maybe by removing the glovebox & pointing the air bomb directly at the air recirc flap. Also, the amount of conflincting info on what settings to use for the air bomb is confusing, heater on low, full or 1/2, what temp. to set, low medium or high. Really confusing. Do anyone know someone who has had this problem & resolved it with a permanent solution as with the cold weather drawing in i'm going to need the heater more & more. The smell occurs on start up of the heater blower with ignition on, you don't need to start the engine & turn the AC on, it also doesn't matter whether it's on fresh air intake or recirculated cabin air you still get the smell & then after about 5-8 mins of the HVAC being on it goes milder! Such an annoying smell i have to resolve it & quick!! Any help, info & advice is very much appreciated. Thanks.

Reggie

I guess I would use the directions on the can. I don't have a A3 but the fresh air intake is in the engine bay on my B4 RS4 and the Q5 - I would take out the sir filter there and spray the can into that opening - with the fan on med - high.