A/C smells sour

[Mike P]

Anyone notice a very sour smell from their A/C? I get a smell from the a/c when I roll down a window (Tolls, Drive thrus, etc.) and the a/c is on. Is there anywhere known that may be holding water in the a/c system that could be turning sour? Any thoughts or suggestions would be appreciated. Mike

[DeeDubya]

The A/C evaporator coil has a pan under it that catches water and directs it out a drain. After driving with the A/C on check the water that's dripping under your truck. This is condensate from the A/C. If it smells sour then you know where the smell is coming from. If it's not dripping then you have bigger problems, the drain is clogged.
Also, you might check the micro-filter. A new clean filter might help.

[TitanBillB]

I have also found on that you should run the air with the AC off for just a bit before you turn it off. I noticed the difference in every vehicle I had after someone told me this years ago. Could be what's happing, maybe not but still noticible if you start now. I usually turn off the AC about 2 blocks before I get home.

[fklentz]

The drip pan in all cars can be a harbor for all kinds of bacteria, wet environment and plenty of fresh air. I sometimes smell a mildew odor from mine but I just ignore it for now. One thing you can do is find the drain for the A\C evaporator and then mix up a mild solution of tap water and bleach, not much maybe a tablespoon of bleach in a quart of water. Then connect a hose to the drain and get some of the solution into the drain pan. If you can find a way to spray it into the evaporator would be better. The evaporator should have a small P-trap in it so as air won't blow out it and it can get mildew in it if A\C not used frequently. The bleach solution aids in preventing any growth in there.

If you go to almost any commercial HVAC supplier they have tablets that are for placing in drain pans that do the same but have a plesant odor in them. Just find a way to get them in there.

[RedMunsta]

I think it may be coming from your doors. After it rains, water can stay in the doors if the door drains are plugged. I had this happen on my frontier.

[Treebasher]

I remember dissecting frogs and rats in biology class. The smell I get smells very close the formaldehyde they pack those creatures in. It lasts for about 10 seconds after I turn it on but then it's gone. It's a little better than my previous Tahoe. That smell was more like dirty wet socks.

I just chalk it up to a dirty microfilter.

Here's another AC thread with some good info.

Why does my AC smell like feet?

I think there is another thread about a stinky door but I couldn't find it. Maybe someone else will find it.

[jjconroy]

I remember reading somewhere that this is common in most new vehicles that have the new refrigerant. It was something about the coils that provide cooling of the air are much closer together, thus mildew, ect was more common. The solution that was suggested was to have a 1 to 10 mixture of bleach and water and poor it down each of the outside air intakes by the windshield. Then flush with freash water.

[40Niner]

I think it may be coming from your doors. After it rains, water can stay in the doors if the door drains are plugged. I had this happen on my frontier

Same here.

[TYTAIN]

Somebody put Sardines on your manifold.

[justamere]

If it is happening with the window down it is coming from the defective window seal that has the mildew smell in it. perhaps defective rubber. Mine were changed and problem went away and came back after 6 months. Joe

[TITANDC]

well i think it has to do with new cars cuz i have that smell when i turn on my a/c and my titans at 1600 miles

[MuskyHunter]

I have in my past vehicles made a funnel out of whatever material is convenient, and put the narrow end on the air inlet. I would then turn the fan on and go back outside to spray Lysol disinfectant. Just be careful and take precautions so that it doesn't come in contact with seats or console plastic.

I had to go through a series of these treatments on my 240sx. To make a long story short, the dashboard shook, the car started to reek, then taking out the blower fan to find a dead mouse that went through centrifugal torture. Lysol did it's job.

[mytitan]

i took my truck in about 6moths ago because my a/c didnt not work. they told me they had to flush out approx 1.5 gal of water because the line was clogged. when i run my a/c i do not have any water coming out under the vehicle since i check it regularly . im thinking its clogged again. anyone know how to fix this problem before i have a major issue w/ it.

[TallTexan]

Early titans had a lot of problems with the condensate line leaking into the truck. First thing you notice is funky smell. Check under your passenger carpet for dampness. Also check under the drivers side.

[Justintoxicated]

Originally Posted by TitanBillB

I have also found on that you should run the air with the AC off for just a bit before you turn it off. I noticed the difference in every vehicle I had after someone told me this years ago. Could be what's happing, maybe not but still noticible if you start now. I usually turn off the AC about 2 blocks before I get home.

Thats great except that untill 06 the AC (Compressor) does not actualy shut off untill you turn the truck off, even though the light goes out. Or maybe thats only if you select defrost or max AC that it is stuck on untill you turn the car off. (All Nissans have this issue untill 06).

I have the smell as well and truck is not longer under warranty. I try not to use the AC. Dealer just said this is normal when I asked them about it. Where should I be looking for water?