A while back my wife mentioned that smoke was coming from the front vents after a bit of driving with the A/C on. This does not happen regularly and the Freeon levels do not change. The other day, I witnessed this myself. There was no freeon odor - it didn't have an odor much at all. Then after about five minutes, it just went away. If freeon was leaking out, my A/C today would not be working, but as far as I can tell, everything still seems to work. To answer some basic questions: 1. No it was not smokey outside 2. No I do not smoke 3. No, it was at 73-degrees, not full cold when this happened. Yes, we were in the car for only a few minutes after leaving the mall (which is approx 30 miles from my house) On the way there, cold A/C, no smoke. -TiM

  • Are there any noises (banging, clanging, etc.) when you run the a/c? Does the a/c run continuously or does it switch on/off? When you drive the car long distances, does the a/c blow the same temperature, or will it start to get warmer as its driven longer?
    – CBRF23
    Jul 22, 2015 at 5:08
  • A/C unit is quiet & operates efficiently. My 07 Camry XLE has an AUTO function. This car has a large dash that gets very very hot, so the A/C unit works pretty hard for the first few minutes of driving on a hot day, then it calms down. It is as cold as I request it to be while in the AUTO mode. I run it in manual at times to verify output remains cold. This morning, I started the car, forgot my lunch, got it then left the driveway. Noticed there was a small amount of water drainage, so the drain tube is not clogged as far as I can tell.
    – user11427
    Jul 22, 2015 at 14:05

3 Answers 3


After running the A/C awhile do you see a puddle under the car while it is parked. It is normal for this to happen. I am speculating that the evaporator drain is clogged or draining slow. The water is collecting and what you see is frost blowing out the vent. If it is smoke it should rise as it comes out the vent due to it being warm. If is frost is will sink slightly as it comes out of the vent.

  • Thanks, but if it were clogged or draining slowly, how come this condition only happens randomly? This is a commute car that drives approximately 90+ miles a day, but the smokey output is not constant - it is rare and random. It happened the other day while we were driving. Then it is gone. I know this car has A/C drainage issues, but I don't believe the drain ever clogs. It is a design issue around the evaporator. That standing water is minimal and causes foul odor when switching from AC to heater as the weather changes.
    – user11427
    Jul 21, 2015 at 21:17

Along this lines of what @mikes said, when the A/C first starts, if it is really humid inside the vehicle, you can get fog coming out of the vents until the A/C brings the humidity down. This is because as the cold air coming off of the A/C hits the interior air, it is condensed, making fog. This probably lasts for about two to three minutes and then all is fine. Could be a bit longer if it's really humid. I used to see this all the time when I lived in the State of Georgia.

  • I live in Missouri near Saint Louis. I used to live in Georgia, so I know the south. Here, humidity is not a problem. It does get pretty hot - but no where near Georgia hot/humid.
    – user11427
    Jul 22, 2015 at 14:09
  • @user11427 - Even so, this seems the most likely cause of the "smoke" you talk about. It doesn't take a lot of humidity, just a really good working A/C unit for this to occur. When you see this happening, put your hand into the mist and see how it feels. I'll bet it feels just like water, because that's what you are seeing. This is completely normal and a property of physics. I actually think it's pretty cool to see, lol. Jul 22, 2015 at 17:09

You did not decribe the smoke. what colour? Smell? You can tell a lot from these details. Did you use heater or cooler? I suggest changing the a/c compressor. They are semi consumable and not expensive and wear out after some time.

  • Smoke appeared to be water based. As stated in the original post, it did not have a freon smell - in fact, not much of a smell at all. Maybe a bit of cleaner odor I used a while back, but that's about it. Smoke cleared itself out of the air about a foot from the vent, so that again tells me it isn't chemical.
    – user11427
    Jul 22, 2015 at 14:07
  • To be honest, A/C compressors are not cheap, and the repair is somewhat painful in that you will need to have a shop evacuate the system, then with your vacuum pump and manifold gauge set, draw the system down to a vacuum for 30 minutes or so. This is basically throwing parts at the problem. I would recommend diagnosis before loading the parts gun and shooting basically with eyes closed and fingers crossed. Especially since there is no smell of R134a (not freon)
    – cdunn
    Sep 16, 2016 at 14:51

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