Windows Steam Up

Discussion in 'Gen 3 Prius Main Forum' started by Friar Tuck, Feb 9, 2011.

  1. Friar Tuck

    Friar Tuck Member

    Joined:
    Sep 28, 2010
    47
    1
    0
    Location:
    uk
    Vehicle:
    2011 Prius
    Model:
    N/A
    The other day I was driving along and as it was cold, I had the de-mister on.

    Once the windows had cleared, I hit the 'Auto' button and fairly quickly, the windows fogged up again. So I hit the window de-mister button again and the windscreen cleared.

    I have always used the 'Auto' button on all my other cars once the initial mist has cleared because this is quiet and has always worked fine. However I seem to find the windows can fog up when the auto mode is selected.(Its also a bit noisy on de-mist mode)

    Does anyone else have this problem (PS it was about 7C 40F outside)

    :)
     
  2. fotomoto

    fotomoto Senior Member

    Joined:
    Apr 22, 2009
    4,735
    3,073
    0
    Location:
    So. Texas
    Vehicle:
    Other Hybrid
    Next time this happens, check the air induction button (fresh or recirculation), select the opposite and see if that works better.

    Although it sounds counter productive, you should try leaving the a/c button on too as it will help dehumidify the air.
     
  3. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

    Joined:
    Oct 17, 2010
    37,563
    26,336
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    We've had similar experience: driving in heavy rain, and set to Auto, it will start to steam up. Hit the front Defog button clears it very fast, but switch front Defog button off and it starts steaming up again, so kind of a viscious cycle.

    One thing that helps a bit: set it to complete Auto, but then override Mode: one push of mode sets it to Heat/Defog (forces it to split air flow to your feet and the windshield). Sometimes that will be enough to clear the glass, without having to resort to the heavy blast of AC air you get with front Defog.
     
    Cris_TM likes this.
  4. twittel

    twittel Senior Member

    Joined:
    Jul 7, 2010
    1,605
    148
    0
    Location:
    Mt. Pleasant, SC
    Vehicle:
    2010 Prius
    Model:
    III

    The A/C button is definitely the answer. Even though you're selecting "Auto" mode, the A/C compressor will not necessarily activate, depending upon inside/outside temperatures. When my interior windows fog, I turn-on the A/C until the humidity normalizes.
     
  5. DumbMike

    DumbMike Active Member

    Joined:
    Aug 21, 2010
    553
    114
    0
    Location:
    Los Angeles
    Vehicle:
    2010 Prius
    Model:
    II
    That's the remedy that worked for me. However, I live in Los Angeles so the temperatures weren't getting anywhere near as cold as the OP was getting. Those really low temperatures can cause a lot of trouble with the general workings of the car.

    I thought that the defrost button was really hurting my MPG. Of course, it might have been just the cold weather. I do not know.

    Mike
     
  6. SlowTurd

    SlowTurd I LIKE PRIUS'S

    Joined:
    Aug 22, 2009
    1,156
    333
    0
    Location:
    nj
    Vehicle:
    2010 Prius
    Model:
    III
    let it fog up in the winter and the next morning you'll be scraping the inside of the windshield
     
  7. s3nfo

    s3nfo Member

    Joined:
    Sep 3, 2005
    164
    23
    0
    Location:
    San Diego, Ca
    Vehicle:
    2010 Prius
    Model:
    V
    I actually like to steam up the windows.........Sorry, couldn't resist
     
    1 person likes this.
  8. GrumpyCabbie

    GrumpyCabbie Senior Member

    Joined:
    Dec 14, 2009
    6,723
    2,115
    45
    Location:
    North Yorkshire, UK
    Vehicle:
    2010 Prius
    Model:
    III
    Hopefully not alone?!?! :eek:
     
  9. priuscritter

    priuscritter I am the Stig.

    Joined:
    Aug 11, 2010
    1,525
    199
    0
    Location:
    Indiana
    Vehicle:
    2010 Prius
    Model:
    III
    sorry to sound negative, but it's a design flaw. windshield is too big or air flow is not set right from the vent, or both. Can rarely get the entire windshield defogged. basically, i have to turn on the main defroster button and keep at least 4 levels of fan going.
     
  10. mainerinexile

    mainerinexile No longer in exile!

    Joined:
    Mar 14, 2010
    403
    72
    0
    Location:
    Maine
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    One solution is to keep the windshield CLEAN. If it is dirty/greasy, it seems to create condensation points for moisture.
     
  11. DataWrangler

    DataWrangler Prius Owner (finally!)

    Joined:
    Nov 17, 2010
    128
    18
    1
    Location:
    West Houston, Texas
    Vehicle:
    2010 Prius
    Model:
    V
    ... and preferably not while ... driving :eek:
     
  12. chado1000

    chado1000 New Member

    Joined:
    Nov 3, 2010
    16
    0
    0
    Location:
    Minnesota
    Vehicle:
    2010 Prius
    Model:
    III
    Just stop breathing. Problem solved.........
     
  13. 32kcolors

    32kcolors Senior Member

    Joined:
    Jul 14, 2009
    5,683
    946
    124
    Location:
    Redondo Beach, CA
    Vehicle:
    2010 Prius
    Model:
    V
    The floating center console now makes that difficult.
     
  14. s3nfo

    s3nfo Member

    Joined:
    Sep 3, 2005
    164
    23
    0
    Location:
    San Diego, Ca
    Vehicle:
    2010 Prius
    Model:
    V
    But the back seatbacks go down (pun intended)
     
  15. Tekdeus

    Tekdeus Shifted to Green

    Joined:
    Dec 23, 2010
    151
    19
    0
    Location:
    Vancouver
    Vehicle:
    2004 Prius
    Model:
    N/A
    Using any A/C or auto mode at all condenses significant moisture on the A/C evaporator coil, which quickly fogs up the window badly as soon as the A/C stops working. Once you start using it, it becomes a vicious cycle that then forces you to leave the A/C on all the time.

    In my Gen II, I make sure to never use A/C during winter or wet weather, and just keep it on defog at low fan speed. Still, the Prius seems to fog up more than other cars.
     
  16. Teakwood

    Teakwood Member

    Joined:
    Jun 23, 2010
    491
    73
    0
    Location:
    New Mexico
    Vehicle:
    2010 Prius
    Model:
    II
    :eek:
    ... and here I thought that "Friar Tuck" had bragged about how he was an "advanced" driver, and knew all there was to know about automobiles.:rolleyes:
     
  17. energyandair

    energyandair Active Member

    Joined:
    Jun 9, 2009
    905
    335
    0
    Location:
    Victoria BC Canada
    Vehicle:
    2010 Prius
    When moisture condenses on the evaporator coil, it flows to the drain pan below the coil and from there out of the car.

    The net effect is to remove moisture from the air within the car which is what you need to do to prevent fogging on the inside of windows.

    There would be a minor rebound effect from re-evaporation of moisture remaining on the coil when the a/c is switched off but my experience has been that this is minor.

    IMHO, the main reason for having a/c in climates like Vancouver and Victoria is that a/c plus heat is so good at defogging on cool rainy days.

    I do find that my Prius tends to fog up more than most cars I believe it's partly that the windshield is larger and more horizontal than most and partly because the Prius prioritizes mpg and requires driver action to keep the a/c on. Personally I'd rather be able to see.

    There are posts in this thread on how to keep the Gen 3 a/c on and I've not noticed a significant mpg hit with my fiddling around, possibly because the Gen 3 a/c is so efficient.

    The Gen 2 is no doubt a bit different but its hard to imagine that the a/c could not be used to advantage when defogging is needed.
     
  18. qbee42

    qbee42 My other car is a boat

    Joined:
    Mar 2, 2006
    18,058
    3,034
    7
    Location:
    Northern Michigan
    Vehicle:
    2006 Prius
    This is a silly comment. The evaporator has a drain which removes condensed water, resulting in less water vapor inside of the car. If that water were not condensed and removed by the drain, it would end up inside the car, causing fogging.

    Cold weather and moisture are responsible for fogging; it's not the fault of your A/C, unless your drain is plugged.

    Tom
     
  19. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

    Joined:
    Oct 17, 2010
    37,563
    26,336
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    I've found AC moisture removal (similar borrowing money, meth, and so on) exacts a cost that does cause a moisture dump, when you turn it off. Found this with a variety of cars. I think it's just that all that collected moisture does not make a complete and orderly departure down a drain tube. A goodly amount hangs on the condensor fins: turn the AC off, and it's baaack. It takes an overnight sit before it really dissipates. OTOH, the Prius seems better in this regard.
     
  20. TheSpoils

    TheSpoils Member

    Joined:
    Jul 30, 2009
    304
    49
    0
    Location:
    New Jersey
    Vehicle:
    2016 Prius
    Model:
    II
    Hitting "auto" will usually cause the blower fan to direct air to the floor. I would suspect that most humidity / moisture would be on the floor where your wet boots sit on the carpet. Try using the windshield defogger setting. And there is a difference between defogger and defroster.

    You're Welcome
     
Loading...