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Auto A/C on 2005 Prius

Discussion in 'Gen 2 Prius Technical Discussion' started by misterskunk, Oct 27, 2011.

  1. misterskunk

    misterskunk New Member

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    newbie here. I just bought a used 2005 Prius with about 75K miles on it and am loving it so far. Quick question. Is there a way to use the "auto" feature on the thermostat without having the A/C on? Like if the temp is 40 degrees and I want to keep out at 68 in the car, how can I set it to "auto" at 68 without the A/C coming on?
     
    #1 misterskunk, Oct 27, 2011
  2. David Beale

    David Beale Senior Member

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    A/C means either heating or cooling, not just cooling.
    With defrost off and the temperature too low (below your setting) the cooling system pump will not run when you select A/C auto.
    If you turn on front defrost the cooling system pump will run to dry out the air.

    So go ahead and select A/C auto, the cooling pump will not run in the situation you listed.
     
    #2 David Beale, Oct 27, 2011
  3. firepa63

    firepa63 Former Prius Owner

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    The AC compressor is variable speed, electrically driven, and will not come on unless conditions warrant.
     
    #3 firepa63, Oct 27, 2011
  4. misterskunk

    misterskunk New Member

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    Ahhhh...ok. So if I select "Auto", and then de-select the A/C switch, does that basically turn off the automatic thermostat feature?
     
    #4 misterskunk, Oct 27, 2011
  5. Tideland Prius

    Tideland Prius Moderator of the North
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    No. You're still in AUTO but the computer will never use the A/C. But in AUTO with the A/C light on, the car will determine the humidity level (not just temperature) to decide whether to engage the A/C compressor. It's not just meant for cooling. A/C is used to dry the air to prevent the windows from fogging up. If you set the temperature high enough, you'll get the heater. I've had the A/C light on at -40, I assure you, it's not cooling ;)
     
    #5 Tideland Prius, Oct 27, 2011
  6. misterskunk

    misterskunk New Member

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    OK thanks. Sounds like it's best to just leave it on Auto and not worry about it then.
     
    #6 misterskunk, Oct 27, 2011
  7. firepa63

    firepa63 Former Prius Owner

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    Correct...
     
    #7 firepa63, Oct 27, 2011
  8. dhanson865

    dhanson865 Expert and Devil's advocate

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    Maybe but I wish I could lock out anything higher than half fan speed in Auto mode.

    I never use auto on short trips as it'll run the AC with full fan speed and it's too annoying. Only way I would consider using Auto is on a road trip.
     
    #8 dhanson865, Oct 27, 2011
  9. Tideland Prius

    Tideland Prius Moderator of the North
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    ECO mode on the 3rd Gen Prius does just that. Even at full blast, the fan speed is lower (maybe not at half speed but when you toggle between ECO and normal during that time, you can hear the fan decrease/increase in speed even though the fan speed indicator on the climate control doesn't change)
     
    #9 Tideland Prius, Oct 27, 2011
  10. dhanson865

    dhanson865 Expert and Devil's advocate

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    I wish they had a similar function on the Gen II.

    But I want the normal pedal mapping with the eco fan control.

    In fact I want the eco fan control even if I'm using the performance pedal mapping (depending on the hybrid and market it's sold in they change the name of that mode).
     
    #10 dhanson865, Oct 27, 2011
  11. Tideland Prius

    Tideland Prius Moderator of the North
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    Then you'd want a 2011 Camry Hybrid before they sell out =). It has an ECO heat/cool button (that's hidden and not illuminated so you can't find it at night lol) and that controls the climate control, only.

    All new hybrids will control the climate and throttle mapping. Tell you what though, the 2012 Camry Hybrid still felt peppy even in ECO mode.
     
    #11 Tideland Prius, Oct 27, 2011
  12. dhanson865

    dhanson865 Expert and Devil's advocate

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    Camry doesn't have the hatchback or the fuel economy.

    I just want to somehow mod my Gen II Prius to use lower fan speeds in Auto AC mode.
     
    #12 dhanson865, Oct 28, 2011
  13. Tideland Prius

    Tideland Prius Moderator of the North
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    Use higher temps, that's all I can think of.

    The 2010's A/C is pretty powerful and I can get away with setting it at 25°C (77°F) for short trips even though it's 30°C outside (86°F)
     
    #13 Tideland Prius, Oct 30, 2011
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