As the weather has warmed up in my location, I've noticed a smell coming from my vents. It does not appear when my AC is on, but rather only when the AC is off. The best I can equate it to is the smell that comes from my hockey equipment bag (which coincidentally has never been in my car).

My first thought was to get a new pollen/dust cabin air filter. I purchased my car with roughly 18,000km on it and it now has 20,000km. It was city driven by the President of a local organization here - and the interior is mint. I don't think he ever had a passenger in it. I looked in the owner's manual (three cheers for me ) and it didn't speak of the interval for which you change the filter - rather it says the MID will tell you when it needs changing.

So I went to Youtube, found an excellent video detailing how you remove/replace your filter (it literally takes under a minute to do, yet the dealer wants a small fortune to do it for you). I then purchased an OEM filter and replaced it myself.

As you can see from the picture below, it was definitely in need of replacing.




The smell, although diminished, has not disappeared. Anyone have any thoughts on why it would emit a smell without the AC but not when the AC is on?

I have heard that it's wise to turn off your AC as you are approaching your destination vs. shutting the car down with it on - something to do with allowing the airflow to assist in evaporating condensation while the car is still in motion. Is it conceivable that my AC lines are dirty/moldy and need to be replaced?

 

I had that problem with my first two Acuras back in the 90's and early 2,000's, not so since. The solution for me was to change the filter 1X per year and turn off the AC when it was not needed anytime during the year. I have always lived in a moderately humid climate and I have been told that in southern very warm and humid climates that these issues are common across all brands. In desert areas it is dust that clogs the filters, not mold. For whatever it is worth, I hope this is helpful in a small way.

 

Spray a entire can of WURTH AC conditioner when ever you change those filters or have the smell of LOVELY BACTERIA blowing out of your AC system. Avoid the pepshop boys joke spray as it doesn't KILL bacteria and mold that is in your AC system. Logic's: Take a glass, fill with ice cubes fill with water, leave it and in 10 minutes or so you will see CONDENSATION on the outer part of the glass....that is the same thing happening in your AC system mostly due to short drives on a HOT day....Acura/Honda's are prone to this....Thank me for saving you a bunch of dough as the stealerships would have hosed you to do this simple job. WURTH is a commercial product and only sell 6 at a time....BUY them as you will do this every 6 months or so... It has a super pleasant CLEAN lemon smell too! Bacteria/Mold free......

 

^^ Exactly right. One way to stave it off is to turn off the A/C a few moments before you arrive at your destination. That really helps prevent the problem.