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AC is automatically ON in AUTO climate control?

Discussion in 'Prius c Main Forum' started by Yves Grenier, Nov 12, 2012.

  1. Yves Grenier

    Yves Grenier Junior Member

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    I am what you would call a newbie and I only used ECO mode so far. When I am using "auto" climate control mode, AC is automatically turned ON. I am somewhat surprised about that feature and I always turn AC off as most of the time I do not need AC and there is no point to spend extra energy when it is not necessary. Is it necessary to turn it off in this case? Am I missing something? It may be that AC will not actually be used unless the car inside temperature is above the target temperature that has been set, in which case I could leave AC ON, but I could not find specific info on this subject in my user manual. Can someone help me to understand why it is working this way?
     
  2. El Dobro

    El Dobro A Member

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    It must vary from model to model. In my Prius, the settings are remembered the next time the car is turned on. If I have the A/C turned off when I shut down the car, it won't be on when I turn on the car again.
     
  3. norahs

    norahs Junior Member

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    I've experienced this too. Even if the thermostat is set to 80 and I want the heater to be on, if I press "auto" the AC light comes on. The air feels warm like the heater but I'm not sure if the AC is actually working since the light is on. I just quickly hit the AC button to turn it off but then the auto light goes off and it goes into manual mode.

    edit: hitting the AC button does not turn off the auto light and it does not go into manual mode.
     
  4. firstrival

    firstrival Member

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    In my Lexus, the AC light was also always on in AUTO mode.
     
  5. Super C

    Super C New Member

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    On a C, to set temperature without turning on AC, hit the fan speed button. You the should be able to raise or lower temperature and set fan speed without AC coming on.
     
  6. dick_larimore

    dick_larimore Member

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    As stated in previous posts, you can turn off the A/C in auto mode and that choice carries over to subsequent engine starts. Note that a lighted A/C button only indicates that A/C might be used to control the cabin temperature. It does not indicate that the A/C compressor is actually in use. The interior temperature setting will determine if the A/C is actually used, and if you are worried about fuel consumption, just keep the interior temp setting higher.
     
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  7. Loopie

    Loopie Junior Member

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    I've managed to have the Auto button engaged without the A/C lit - took a bit of fiddling around, but I think what worked was upping the temp setting. I've been meaning to consult the manual........but you know how that goes.

    However, on the days when it's really humid (though chilly), it helps to have the A/C removing the moisture from the air - keep the interior glass surfaces clear (windshield, etc)
     
  8. ahmeow

    ahmeow Prius Lover

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    Yes the A/C light on only indicate the Auto climate system is on and that doesn't mean the compressor is using. Auto climate control is not only to provide cool air in Summer or when humidity is hight but also giving out warm air in Winter. When you have set your desire Temp. cool air will provide when the cabin Temp. is higher or to provide warm air when the cabin is lower than the set Temp. That's climate control. Don't just think of making cool air always.
     
  9. Loopie

    Loopie Junior Member

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    Very well put, thank you. This is my first car with auto climate control, so I'm still getting used to the controls and functions.
     
  10. Rob.au

    Rob.au Active Member

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    Hmmm, can't work out if my experience is the same or different from others are describing.

    When I want to shut down the car, if the AC is on, the first thing I do is press the AC button so the indicator extinguishes. Then I press OFF to disengage the fan and the indicator next to AUTO extinguishes. I like a "clean" start up, so I turn everything off before turning the car off.

    What this means is that when I do next press AUTO to turn the fan on, the AC never comes on automatically. I have to deliberately press that button if I want it (which is the desired outcome in my case).

    I gather that the only reason why the AC would come on automatically would be if you didn't disengage it first last time you turned the fan off... unless my car is totally different.
     
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  11. Ashley7

    Ashley7 Active Member

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    For what it's worth, mine always stays in Auto after I turn off the AC, so I'm not sure why it goes into manual mode if that's all you press. Mine only goes manual if I change the fan speed.
     
  12. crebble

    crebble Member

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    It's a safe bet that the compressor is running when the A/C indicator is lit and the outside temperature is > 0C /32F.

    I know mine does. Great for clearing the windows.
    Pg. 243 in the manual.
     
  13. vincent1449p

    vincent1449p Active Member

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    It is the same with our ver., I need to manually press the A/C if I want. I've checked the customization options with TechStream, there is no setting available in our ver.

    In the US user manual, pg 237:
    I also checked the GenIII Repair Manual, there is a customization option called Compressor Mode:

    Compressor Mode.jpg

    I guess US ver. Prius C also has this option, that may explain why theirs are different from ours.

    Vincent
     
  14. Rob.au

    Rob.au Active Member

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    Nice find, but I've just looked and the wording in the Australian manual is identical. I can absolutely say that if I've pushed the A/C button and made its light go out, then it does not operate until such time that I push it again.

    The only exception to this is pushing the Front Defrost button, which will do several things automatically including activating the A/C (making the indicator light for it come on).
     
  15. oberkc

    oberkc Junior Member

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    I wonder, too, if "ECON" mode affects automatic engagement of air conditioner
     
  16. ThaSaint

    ThaSaint Go Big Blue!

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    When I hit auto it turns on the AC, no matter if the fan was already on, ac was off, car was off, doesn't matter. IT DRIVES ME INSANE! I've owned other cars with climate control and have never had this happen. Auto means AUTOMATIC, if it's hot outside, it'll turn on the AC and the light will turn on. If it's cold out, no AC light turns on. My OCD really shines through on things like this.
     
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  17. Tideland Prius

    Tideland Prius Moderator of the North
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    Keep in mind that the MODE is still automatic (and vice versa, if you're in AUTO and you change only the MODE, the fan speed is still in automatic mode). You'll have to fiddle with both for "true" manual mode.
     
  18. Ashley7

    Ashley7 Active Member

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    I'm not sure I follow what you're saying. When I change the fan speed, the Auto light turns off. And nothing automatically changes after that, neither speed nor mode. Maybe the liftback is different from the c?
     
  19. Tideland Prius

    Tideland Prius Moderator of the North
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    Yes the AUTO light will go off if you change the fan speed or the mode. What I'm saying is that it will still adjust according to outside conditions. For example, in the winter, if I change the mode so that it blows warm air to the face (rather than the feet), it will increase the fan speed accordingly as if it was in AUTO (even though in AUTO, it will blow to the feet to warm them up).

    Vice versa, in the summer if I touch the fan to keep the fan speed low, the mode will change if I decide to bump the temperature all the way up so that the heater comes on (I know it's silly but I was just experimenting).
     
  20. norahs

    norahs Junior Member

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    I have to retract my previous statement and agree with you. I tried it again yesterday. Pressing Auto showed the AC lit up even though temp was set at 77 and outside temp was 65. Then I pressed AC so it was no longer lit up and the Auto light was still on.

    I'm still confused as this thread has both answers. When pressing auto and the AC light comes on, does it mean that the AC compressor is in use?