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Defroster Air-Conditioned by Design?

Discussion in 'Gen 2 Prius Main Forum' started by YBLee, Jun 29, 2006.

  1. YBLee

    YBLee Junior Member

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    Before you all ask me if I read the Owners manual, let me say "yes and no"! I read most of it but skipped the chapter on Comfort Controls like Defroster because I just figured it had to be pretty much the same from my Odyssey BUT, not so so here we go:

    I noticed this morning that when I initiated what I thought was "DEFROSTER" mode WITHOUT" the AC lighted, I started to feel what appeared to be cool air and then condensation on the outside of the windshield. I double checked to insure I had not actually turned on the AC in the MFD and sure enough it was off BUT, I am getting AC conditioned air to the defroster.

    IS this normal and is this particular to Toyota or just the Prius?

    Thx in advance, Lee
     
    #1 YBLee, Jun 29, 2006
  2. Marlin

    Marlin New Member

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    The "Defroster" is more accurately a "Defogger". It's purpose is to remove the condensation that builds up on the inside of the windshield when the air is very humid and the windshield is cold. This is best accomplished not by blowing more damp humid air on the windshield, but rather by blowing dry air onto the windshield. Thus, the use of the air conditioner. Air conditioners remove moisture from air as they cool it.

    Using the A/C while in the windshield defrost mode is actually common behavior for many cars, I believe. My Ford Explorer did it, and my Chevy Malibu did it.
     
    #2 Marlin, Jun 29, 2006
  3. KMO

    KMO Senior Member

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    To further expand...

    The manual suggests that if you want to deice the outside of the windscreen rather than demisting the inside, you should select the front window "defrost", turn the A/C button off, and set the heat and fan to maximum.

    Also, one of the dealer-settable options via the diagnostic tool is to disable the automatic activation of A/C with the defrost button. (Another option can disable the automatic activation of A/C with the AUTO button).
     
    #3 KMO, Jun 29, 2006
  4. YBLee

    YBLee Junior Member

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    Yes, I generally do this but on all my other cars, it is optional. With my Prius, it does not appear to be optional so when you invoke Defroster/Defogger, AC is automatically applied even if the "AC" toggle on the MFD is in the "off" position or "not lite".

    Nicely done KMO. That explaines it completely. Thx a lot.

    That's also Marlin for the feedback.
     
    #4 YBLee, Jun 29, 2006
  5. KMO

    KMO Senior Member

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    Hmm, then it looks like your 2006 is behaving slightly differently to my 2005.

    On mine, the A/C light does come on when you activate DEFROST or AUTO, but you can turn it off again. I've not heard this difference mentioned before.
     
    #5 KMO, Jun 29, 2006
  6. c4

    c4 Active Member

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    On the Classic, the defrost mode does turn on the A/C, but the light does not come on..
     
    #6 c4, Jun 29, 2006
  7. Betelgeuse

    Betelgeuse Active Member

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    <div class='quotetop'>QUOTE(KMO @ Jun 29 2006, 09:37 AM) [snapback]278533[/snapback]</div>
    Right. And that's what YBLee is saying is happening with his/her car. *However*, the point that (s)he is making is that, even while the A/C light is off, the air conditioning compressor is running and pushing A/C-ed air through the vent.
     
    #7 Betelgeuse, Jun 29, 2006
  8. YBLee

    YBLee Junior Member

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    Betelgeuse is exactly right!
     
    #8 YBLee, Jun 29, 2006
  9. San_Carlos_Jeff

    San_Carlos_Jeff Active Member

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    <div class='quotetop'>QUOTE(YBLee @ Jun 29 2006, 07:28 AM) [snapback]278519[/snapback]</div>
    This is how my Explorer, Acura, and Audi did it too. I think it's pretty ubiquitous on cars nowadays.
     
    #9 San_Carlos_Jeff, Jun 29, 2006
  10. walt

    walt New Member

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    <div class='quotetop'>QUOTE(YBLee @ Jun 29 2006, 08:28 AM) [snapback]278519[/snapback]</div>
    My '99 Dodge Caravan did that. Pretty standard, I think.
     
    #10 walt, Jun 29, 2006
  11. Tideland Prius

    Tideland Prius Moderator of the North
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    Yeah.. most new cars with or without automatic climate control will have this since it's assumed if you were choosing that mode, you want to clear the windshield. Older cars with manual A/C, you'd have to do it separately.
     
    #11 Tideland Prius, Jun 29, 2006
  12. Jack Straw

    Jack Straw New Member

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    zzz
     
    #12 Jack Straw, Jun 29, 2006
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