My 07 Civic has developed a musty stink when I run the defroster, but ONLY on the recirculation setting.

As soon as I turn recirculation off, it goes away.

Something clogged up somewhere? I just replaced the cabin air filter thinking it was that, and the old one was pretty gross but it keeps doing it.

Any ideas?

Is there any steam, or a sweet smell? If so, heater core could be starting to leak.

Dead critter in the system?

BTDT.

does it have a sun roof?
Went thru a problem with clogged drain pipes in my grand cherokee
Simple fix for me ,pulled carpet up slightly and opened up the 1/2 bladder and flushed with water.

Mold and mildew would cause a musty smell.

How to get it out is another question. Ozone generator?

mice, as already mentioned.

It smells fine on any other setting than recirculate.

Wouldn't dead animals smell all the time no matter what setting?

It's a musty/mildew smell, not a dead animal smell.

No sunroof.

Does it have a cabin filter? If so, that may need to be changes.

PC

quote:

Originally posted by PCWyoming:
Does it have a cabin filter? If so, that may need to be changes.

PC

My OP states that I had just replaced that recently.

quote:

Originally posted by PASig:

quote:

Originally posted by PCWyoming:
Does it have a cabin filter? If so, that may need to be changes.

PC

My OP states that I had just replaced that recently.

Yeah, but you didn't add it until the 4th sentence? Who the hell can read 4 actual sentences in the very first post of a thread?

Come on man.

If you normally use recirc mode you definitely do not want to leave it in that setting when parked I've been told. The outside airflow will keep the mildew down if you leave it on fresh as much as possible, or change to that before shutting down.

Not sure how to remove the funk once there....

Spray some of this in the intakes located under wiper blades while the heat/AC is on. This stuff will knock out any odd smells.

That, or Lysol. Be sure to let it run on recirculate for a while, after.
It may take a few applications over a week as the Lysol kills the bacteria.

Bruce

I see you’re in PA and you’re probably not running the AC yet. If you ran the AC on recirc you’d most likely smell the same odor. When you run the defroster the AC compressor comes on, helps the air get dryer so the defroster is more effective. BTW recirc is the same as MAX setting.

I’ve seen this problem many times before, I used to be in automotive service management.

Your car has a clogged or restricted water drain line, there is a line hanging down and the condensate runs out of it onto the ground.
Ever notice a puddle of water under a car sitting for a few minutes with the AC on? That’s this. The water was retained in the evaporator case and stagnated, bacteria grew, became moldy and stinks. In RECIRC or MAX mode the blend door is moved to shut off outside air, which is warmer, and the system goes to cooling already cook air, making it much colder out of the vents. Basically the defroster works through the AC system.

You need to make sure this line is clear.

Often times spraying Lysol in the fresh air intake (located by the wiper blade) will kill the bacteria and odor. Try this first. You can also buy a stronger sanitizer if a can of Lysol isn’t strong enough.

If that doesn’t work, do this: Go to an auto parts store and buy a AC drain cleaner and deodorizer. Here’s an example LINK

This kit has a tube you insert into the drain tube and physically clears a clog. The spray is stronger and kills the bacteria.

Here’s a tip: When you run the AC on recirc, a few minutes before stopping the car turn the AC back to normal mode. This runs much more outside air through the evaporator case and helps drain water out, preventing this issue.

I was driving Sis’s new Jag recently, when you put the AC on recirc it cools much better but after 10 minutes or so it turns recirc off and back to normal. I like this feature a lot, it greatly reduces the chances of getting the odor issue.

Good luck to you.

quote:

My 07 Civic has developed a musty stink when I run the defroster, but ONLY on the recirculation setting.

I'm a little surprised that it allows you to run recirc while defrosting. Most newer cars (to me, a 2007 is still fairly new) don't, and if you try, they won't let you. Anyway, you've probably got some of the same crap on your evaporator that contaminated the cabin filter. It is also possible that the water drain hole/passage/hose is clogged. Do you hear any sloshing? When you select fresh air it clears out the stink somewhat, like opening the windows in your house when something stinky is in it. There are products you can buy that you fog in through the cowl vents.

I have seen people use steam cleaners to clean/sanatize their vents?

Total agreement with OKCGene.

Yep. Own a Honda myself.

Do what okgene says. I have to do this to my police car every few months.

Large can of Lysol.
Run heat on max. Spray Lysol into intake for a minute. Let system run then switch to ac. Spray Lysol some more. Then run defrost and spray Lysol. Then switch to ac recirc and spray Lysol some more. I pretty much use up the can.

Make sure to have all windows open when doing this.

Should make this thread a stinky—I mean a sticky.

Have you considered showering and deodorant so you're not stewing in your own recirculated scent? Until then, dilution is the solution to pollution (i.e. don't use recirc, bring in outside air)


Link to original video: https://youtu.be/f53CcQWqGoo