Stinky Smelly mildew smell from AC for the first few seconds at startup

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by robsnyder20, Oct 17, 2018.

  1. robsnyder20

    robsnyder20 Active Member

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    I commented on a few threads and a few of you replied but I feel like I need a dedicated thread because I cannot seem to get rid of this mildew odor for the first few seconds (3-5 seconds) at startup when the AC or vent comes on.

    Things I have tried:
    1) I had toyota do their Refresher AC service...Smell came back after about a week and a half
    2) Lysol in the intake over multiple days...Smell came back
    3) Discontinuing AC use for the last couple miles and running system on high to dry it out...Smell still there, but maybe less strong
    4) Bought the Genuine Toyota AC refresher service kit myself and put the entire evaporator treatment in the evaporator tank from the drain hose all at once, it does come out on the mats...Seemed to work but smell came back after a week or so.
    5) Used caristra to try and shut off opening the vents when turning off the car, but that only seemed to make the smell stronger at start up
    6) Ran the heater for approximately 2x1 hour trips, seems to have no effect once the system gets moist again.

    What does work, not running the air, when the system is dryed out completely, there is no smell whatsoever, so I know it is a mildew, wetness issue. So I guess the good news is there isn't something inside the system thats causing the smell like a rodent or something, but the bad, how do I get rid of the nuance smell at start up for the first few seconds?

    Side note, I'm in SW florida and the car is garaged which probably doesn't help, but not running the AC really isn't an option and I looked around the forums and I can't seem to find a solution to my issue on the earlier models. Thanks for the advice in advance. BTW I am past the 36K warranty.
     
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  2. Smaug1

    Smaug1 Member

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    I had the same thing in my Accord; I think it's just the nature of A/C in a car. I thought it was a moldy cabin air filter, but after changing it, the smell quickly came back. What's funny is that I don't recall older cars from my family having this issue. ('86 Escort, '86 Merkur, '97 Civic, '04 Sentra) NONE of them had it.
     
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  3. bisco

    bisco cookie crumbler

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    that's bad for a fairly new car. i would go back to the dealer and complain.
     
  4. Starship16

    Starship16 Senior Member

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    I run my AC every day. I get that smell too, just like yours but only rarely ( For only a few seconds at start-up. ) And it always seems to happen when the outside vent is open. When I have the "Recirc" button on, I never smell it.

    And Smaug1 is correct, none of my cars in the past ever stunk. :LOL: Another Prius Oddity.
     
    #4 Starship16, Oct 18, 2018
    Last edited: Oct 18, 2018
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  5. sam spade 2

    sam spade 2 Senior Member

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    It's a fairly common problem with a LOT of makes and models.

    To really find and fix it, one has to take the ENTIRE A/C and air distribution system apart and clean and sanitize every part.
    That might cost you near to a thousand dollars.

    Notes: You might have mold growth in the fresh air intake outside of the actual A/C system....usually below the windshield.
    Sometimes trees sprout in there.

    By "garaged", does that mean that it is covered nearly 24 hours a day ??
    If so, it might benefit from sitting out in the hot sun for 8 hours for a couple of days in a row.

    And finally, I don't know what causes it but some evaporators seem to be made with defective materials that give off that odor when clean and new when they get damp. I think Ford had a bad batch a few years back........and my new home A/C had a similar problem and they finally replaced the evaporator and the problem went away.

    I have NOT heard of this defect lately though. Maybe they finally figured out what in the manufacturing process caused it.

    Good luck.
     
  6. Starship16

    Starship16 Senior Member

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    I sprayed 1/2 of a large can of Lysol in the outside vents by the windshield wipers. With the AC running inside. (Somebody posted a YouTube link several months ago.) I think it helped somewhat. They say to do it a couple times a year.
     
  7. Usle

    Usle Member

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    SW florida, in a closed garage, sounds like white mold, I'd get that professionally treated then I'd get the garage opened up to air with screens.
     
  8. JosephG

    JosephG Active Member

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    Sorry for the necropost, but I have been struggling with this problem even in dry California.

    I believe the reason the Prius has this problem is the eco AC settings that reduce fan speed and only blow on the driver causing the evaporator to have insufficient airflow to dry the coils. I turned off the auto fan control and it seems to help a bit, though I think I need to clean the evaporator to truly fix the problem.
     
  9. robsnyder20

    robsnyder20 Active Member

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    Just to give a quick update from my earlier issue. If I run the fan on high for the last 2 or so minutes of my commute with the AC offf, fresh air on, before I garage the car, it seemed to have resolved my issue. I even set up little chimes thanks to the factory GPS to remind me to do this chore. It however has seemed to resolve the issue.
     
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  10. ttou68

    ttou68 Active Member

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    How about new Air filters... Particularly in cabin air filter, one with charcoal..

    Posted via the PriusChat mobile app.
     
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  11. ColoradoBoo

    ColoradoBoo Active Member

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    Yep and change yearly as the charcoal only lasts that long. On Amazon, I get the Fun Driving Filter (Amazon) #TK4861J6x, two for $17 bucks....
     
  12. rjparker

    rjparker Tu Humilde Sirviente

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    It is dirty sock syndrome, a mold on the evaporator. If the evaporator is dry you won't smell it on startup but it will be there. When the evap gets cold and is running condensate, you won't smell it either.

    Central systems can have the exact same thing. There are commercial evap cleaner products like Viper Evap + that are cheaper to buy but harder to use than the Toyota foam cans.

    What I did was add a length of hose to the condensate drain so it was easy to grab it from the wheel wheel. Then use a can of evap cleaner foam every week until the evap is truly clean. It takes time because the mold combines with dust and lint to create gunk which has to breakup and flow out the condensate tube without brushing and rinsing. Do not use bleach or commercial condensor coil cleaners. You will be very sorry if you use them on a Prius evap because you may get to do a complete dash disassembly and parts replacement.

    For central system evap coils you start out clean and add a UV light shining on the coil. Works wonders.

    Safe Central Evap Cleaner
    https://www.supplyhouse.com/Refrigeration-Technologies-RT350G-Viper-Evap-Coil-Cleaner-Deodorizer-1-Gallon?utm_source=google_ad&utm_medium=shopping_neutral&utm_campaign=Shopping_Neutral_LPLTV&gclid=Cj0KCQjwhqaVBhCxARIsAHK1tiPdGBEq1Oc56vN7sLR6BFD2Qpoocht_UEZu5a61HkHgBFtnRilo_Q8aAmjuEALw_wcB
     
    #12 rjparker, Jun 15, 2022
    Last edited: Jun 15, 2022
  13. douglasjre

    douglasjre Active Member

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  14. BiomedO1

    BiomedO1 Active Member

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    I just keep the HVAC system in manual mode and the fan is on low all the time. This keeps the coils dry and prevents mold growth.

    Also check your condensate drain; it may be clogged. You should have water dripping out of it; if your using the AC.
     
  15. douglasjre

    douglasjre Active Member

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    If you're using air conditioning how does that keep the coils dry?
     
  16. Mendel Leisk

    Mendel Leisk Underfoot

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    Once mold starts I’d speculate it’s pretty tenacious. If you do get it clean, to avoid reoccurrence:

    1. Use AC (meaning the Freon-style compressor system) sparingly. If it’s not oppressively hot, and/or for short trips, just roll down the windows.

    2. ALWAYS turn off AC at least a mile before your destination, but keep the blower going at a moderate speed, to exhaust moisture.

    appreciate this is a pain, but it works.

    if tearing apart the dash is required to clean, that’s a real pain.
     
  17. PaulDM

    PaulDM Active Member

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    I found spraying the air vents with a domestic anti bacterial spray over a couple of days helps.
     
  18. BiomedO1

    BiomedO1 Active Member

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    It would probably be more effective, you place the fan on high; pull out the cabin filter and spray in there. That should push the spray through the coils; exiting your vents.
     
  19. Mendel Leisk

    Mendel Leisk Underfoot

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    There is a technique, and a bottle of cleaner, proscribed by Toyota. I believe you introduce the cleaner through the AC water drain tube.
     
  20. PaulDM

    PaulDM Active Member

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    But with all these “pull through” methods the spray would be diluted by the time it got to the vents. Just saying do this in addition to the previous guidance.