Stinky Air Conditioning and A/C Misting Services

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Does the air coming out of your climate control vents smell like your grandma’s cellar? If so, you’ve probably got a little mold or mildew growing in the evaporator and/or duct work. To get rid of it, you’ve got three options:

1. You can shut off your A/C a mile or two before your destination but leave the fan speed set to HI. This will help dry out the system and keep the little guys from growing. Hopefully, they’ll die out.

2. You can use some chemical weapons on the fungi, bacteria, etc.

3. You can take the A/C apart, clean up the evap and any duct work you can get to, and then put it all back together.

Ready to get started? Here’s how you go about it:

Animal House motivational speech

This image from - click to see the original.

1. Get some inspiration. OK – this step is totally optional, but nothing gets me going more than this speech from the movie Animal House:

“What?! Over?! Did you say over? Nothing is over until *we* decide it is. Was it over when the Germans bombed Pearl Harbor? Hell no…and it ain’t over now. Cause when the goin’ gets tough – the tough get goin!…now, we could fight em’ with conventional weapons, but that would take years and cost millions of lives. No no no. In this case, I think we have to go all out.”

You can watch the video clip here (not safe for work)…now back to work.

2. Keep things dry. When A/C units make air colder, they create condensation. Most of this condensation collects on the evaporator coil, where it is supposed to drain off harmlessly. However, some vehicles have problems with moisture sticking around…and that’s when the little guys start stinking up the joint.

SO, you just need to help your car out a little. Turning off the A/C (but leaving the blower motor on) a couple of minutes before you reach your destination is a good way to keep air moving across the evaporator and help it dry out.

3. Get chemical. There are some chemical weapons at your disposal you can use to kill mildew and mold. BG Products, for example, makes Frigi-Fresh and Frigi-Clean, two products designed to clean out your A/C system. They’re both available at your local dealership, but you can also buy a kit online and DIY.

BG Frigi Fresh and Frigi Clean

BG Products are often found at auto dealerships, but they're not the only option for this type of product, so shop around.

To use one of these chemicals, turn on your car, set your A/C to “recirculate”, and follow instructions (usually 30 minutes of operation are required).

4. Time for a tear-down. Sadly, if parts 1-3 don’t get it done, your next best option is to start taking things apart. If you’ve made it to this part, you deserve to know two things:

  • It’s hard to get a climate control system to go back together the same way it came apart.
  • It’s not always bacteria and fungus that can cause bad smells. Mice and other small creatures sometimes crawl into vehicle systems. When they die…well, you know the rest.

5. Beware “misting” services. Some dealers sell preventative “A/C misting” services, but according to the dealers I’ve spoken with, the benefits of a preventative treatment are dubious. First, your car simply may not need it – it may be a waste of money.

Second, if your car has a mild cause of mold or mildew and it’s not treated properly, whatever “mild” mold or mildew that survives will come back stronger and stinkier. In other words, preventative misting might actually make the problem worse…so skip it unless your car is already starting to stink.

**Special thanks to Brad for asking us about A/C misting and getting this post started!

Filed Under: Maintenance Tips


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  1. mk says:

    Is this treatment covered under warranty?
    My former 2007 stunk so bad after 2 years and 26 months I was going to puke it was that bad. The musty mold smell ONLY came on while running the A/C or even the defroster and went away after several seconds up to 1 minute instantly of turning the AC or defroster off. Definitely was AC related. This past summer with only about 5-6K on my 2010 Tundra brand new, the same musty/stinky smell happened on my brand new tundra, but not as bad as my 2 year old Tundra did. I think Toyota has a definite problem and should issue a TSB on this because for me anyways, it is a problem so bad at times in the summer running AC that once my family and I had to pull over and get out of the truck it stunk so bad from the AC stinky smell. Yet another toyota tundra AC problem. I had my former 2007 tundra checked out for rodents which I was 100% sure before and they found nothing, but did smell the stink but of course, at the time, it was barely noticeable unlike other times. Why in the world does ONLY my tundra stink so bad running AC in the summer vs. any of my GM or Toyota vehicles not doing it ever. Seems to me there is an issue with my Tundra’s AC ductwork and AC compressor, etc.. I heard also you can remove the air cleaner filter under the glove box and turn on the AC ductwork on high and spray some lysol, etc. in the ducts behind where the cabin air filter sits – is that a good idea?
    Good article though.

  2. Deznutjob says:

    My 2000 Tundra smelled like a nasty soggy pair of old gym socks left in the locker for 3 months. It got sooooo bad I DID in fact tear my system down as far as I could and clean it spotless!
    The smell returned within a year so I decided to change my AC use habits which was not using it as much AND keeping it at a lower setting.

    The problem with Toyota AC systems is the ridiculous amount of condensation they produce especially on warmer or humid days.

    I’ve spent a lot of time surfing in Costa Rica and our rental car of choice was always the Toyota 4Runner. The Toyota AC system in that thing along with the extreme humidity would actually cause the dash vents to look like snow blowers! =o Kinda cool at first but after a while it would get annoying.

  3. mk says:

    Yep, mostly warm, muggy days it smelt, but other times not that warm and humid, just when running AC/defrost. Very stinky to smell it and disgusting. Very odd in over 15 new vehicles the past 20+ years of driving, the tundra truck is the ONLY one having this problem for me anyways.

  4. Art64 says:

    I replaced the stock regular cabin air filter with the charcoal impregnated filter and it doesn’t stink anymore. Cost a bit more from the dealership. I believe there is an aftermarket version. I forgot what brand though.

    2007 Tundra Reg Cab

  5. Jr says:

    I wrote up a DIY on tacoma world for this, It worked for me very well.

  6. Jason says:

    mk – It’s not warranty unless it happens during warranty…not sure why your truck is giving you trouble with this. You might get into the habit of shutting off A/C (but leaving the fan on) a few minutes before you end your commute…could help dry things out.

    Dez – It’s a lot of work to get rid of a smell sometimes. I hate it when it happens – I smell it forever even if others don’t.

    Art64 – Good idea! I didn’t even think of that.

    Jr – Thanks for the link!

  7. mk says:

    thanks JR, I will go out and buy a can of lysol since I’m sure it is a lot cheaper than a can of frigi-fresh. I’ll also check my cabin air filter behind the glove box even though my 2010 tundra has only 16K on it and 1 little over 1 year old. Heck, 4-5 swipes across the duct work outside below windshield with hood up with AC on high and recirculate button off cannot hurt anything I would think? I will also try turning the AC off a few minutes before coming to a stop to let things dry out and hopefully prevent the leftover stench from condensation. Problem is the stench also happens in the winter time when I run the defroster a lot most of the time everyday driving and leave it on all the time usually.

  8. Jr says:

    Anytime Yall :). yeah ive tried letting my stuff air out, but meh. The Stink still comes back every month or so for me, But since the weather has gotten drier in houston i havent had to do this for a while. I also started spraying down the air filter as well, not only does lysol smell good, it also kills germs,baceria and whatnot. (Let your air filter dry before putting it back). Another thing to check is; i dont know about the tundra, but the tacoma’s roof is like a Velcro/cloth type thingy, spray that down too same for the seats and the carpeting on the floor. Pretty much anything cloth can collect odors/bacteria easier than leather. im pretty sure 4-5 sweeps wont do anything, but hey im a teenager and i cant afford to screw anything up on my truck (thank god its a toyota LOL).

  9. Mickey says:

    Haven’t had that yet. Got my truck back from the shop and $4,000 later. Jason I don’t and I can’t no more replicate that SUA. Apparently what was causing that was in the tranny’s pressure control sensors. The Torque convertor basically fell apart and caused a massive destruction in the tranny.

  10. Jason says:

    Mickey – That sucks. Sorry to hear it.

  11. Art64 says:

    You’re welcome Jason. Happy with the results. I installed the charcoal filter back in May or June of this year, when I changed my oil. So far, still doing good. There’s some wet rag smell for a few seconds, but after that it’s normal again. No funky, rotten egg smell. And the next day you turn the blower on, no smell at all. The filter doesn’t seem restrictive at all.

  12. Jason says:

    Art64 – I’ll have to write an article about those…thanks again.

  13. mk says:

    Just did the lysol treatment thru the grill behind the hood with A/C on high no recirculate on hottest setting for 5 minutes spraying the plastic vent in front of windshield back and forth 4-5 times with engine running. Also took the cabin air filter out, very, very lightly misted from a disance the cabin air filter to not get it damp, just a light mist. For the heck of it while the cabin air filter was out, I sprayed into the 2 small fans where the air filter was while on high 2-3 times. Couldn’t believe how fast the mist evaporated within 1 minute the lysol moisture was gone. So far, so good. Did not replace cabin air filter yet at 20K but could use a new one very soon since no longer white, but not black yet, only gray with only a few small leaves/bugs to shake out. I couldn’t stand it any longer and had to do something because the stench using the defroster here in WI warming up into the 50’s was not tolerable to drive the tundra any longer, it was that bad. Wish me luck and if smell comes back, gonna have to buy a cabin air filter. If stench is still there after new cabin air filter, gonna have to sell the thing?

  14. Jason (Admin) says:

    mk – There’s some more industrial strength stuff than lysol. The kit from B&G is supposed to work really well…something about foaming up inside and killing everything.

    Hopefully, the Lysol worked. 🙂

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