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Don't quite understand the climate control system

Discussion in 'Prius c Care, Maintenance and Troubleshooting' started by jhearl, Jan 9, 2014.

  1. jhearl

    jhearl Junior Member

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    This is the first car I've had with a climate control system. Got the car (C2) in mid-November 2013, so I have generally wanted cabin temps higher than outside air (I live in Virginia). I haven't had any need for cooled air. I have the temperature set to 71 and prefer to have the heat coming out at my feet only. I've got the display with the seated driver so the arrow is pointing at the feet, so I understand that. And I understand outside versus recirculated air. I also understand that the fan up/down button changes the speed of the fan. But I can't seem to figure out the impact of the A/C and Auto buttons.

    If both the A/C and Auto buttons are off, I still get heat. That's OK now while it's cold outside, but what will happen when it gets warm outside and I just want fresh outside air coming in with no additional heat and no artificial cooling? At this point, I can't see that turning either the Auto or A/C buttons on or off, independently or together, makes any difference in the heat output. The manual is not very helpful and I couldn't find any posts in the forums that seem to address my questions.

    Would someone be kind enough to explain the operation of the controls for me? I guess I have two questions - how should I set the controls to get heat in the winter and how should I set the controls to get fresh, unconditioned air in the spring? I'm assuming, perhaps incorrectly, that come summer when I want cold air, I'll turn on both the Auto and A/C buttons.

    Thanks in advance -
    John
     
    #1 jhearl, Jan 9, 2014
  2. mmmodem

    mmmodem Senior Taste Tester

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    For ease of use, leave on AUTO and set to desired temperature. That's the way Toyota intended it to be used. If you wish to experiment, it's an exercise in futility. Here's what I do.

    I usually want fresh outside air, warm in the morning and ambient in the afternoon. And so in the afternoon I turn on the fan to turn on the HVAC. I quickly turn temperature to LO.

    I don't use AUTO or AC because air conditioning might turn on. In the morning I do the opposite and turn up the temperature for heat.

    I only use AUTO when it is hot and I need air conditioning. And yes, in the summer, I just set it to desired temperature and let it do its thing. I never use the AC button except to turn it off. Sometimes it's lighted when I want heat which bugs me.

    If you had it set at 68 degrees in refresh in summer and the HVAC is off, hot air will come in. In other words, if you don't use AUTO, anything above LO is heat.

    Turn off signatures in Tapatalk Tapatalk
     
    #2 mmmodem, Jan 9, 2014
  3. bisco

    bisco cookie crumbler

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    if you set the temp to low, turn a/c and autu buttons off, set vent to outside/fresh, and set fan to your desired speed, you will get fresh outside air with unchanged temp.
     
    #3 bisco, Jan 9, 2014
  4. Raidin

    Raidin Active Member

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    A/C is air conditioning of course, but what it generally means is conditioning the air to be favorable for people. In cars, this usually means dehumidifying the air. Please correct me if I'm wrong, anyone.

    When you put the unit on Auto, you're telling the car to maintain the temp you have set. The car will do this by increasing or reducing the fan speed to get you there within a specific rate that Toyota sets up in the A/C's computer (the further the interior's temp is from what you set, the faster the fan speed, etc.)

    I believe the car also determines if the outside air is too humid or not, and if it finds it to be, it will activate recirculation so it can keep the air "conditioned" with the A/C system on (to dehumidify). If it's nice outside, it will turn off the recirculation and just function normally.

    If you want fresh air but no change in temp, set the temp and hit Auto, and then turn off recirculation if it ever comes on.

    Beyond this, the car will also send warm air to the lowest vents, and cool air to the highest vents, as this is what is most efficient for heating/cooling the car respectively.
     
    #4 Raidin, Jan 9, 2014
  5. ztanos

    ztanos All-around Geek!

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    Set to desired temperature and then turn it off. The car will attempt to provide this temperature to the best of it's fanless airflows ability.
     
    #5 ztanos, Jan 9, 2014
  6. denali123

    denali123 Junior Member

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    The temperature control valve will stop at the position whenever you turn the system off.
    That was why both A/C and AUTO buttons are off you still get heat...

    aaa.jpg
     
    #6 denali123, Jan 9, 2014
  7. drysider

    drysider Active Member

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    Well that clears things up....
     
    #7 drysider, Jan 9, 2014
  8. bisco

    bisco cookie crumbler

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    it's only 50 pages of the manual, what the question again?
     
    #8 bisco, Jan 9, 2014
  9. jhearl

    jhearl Junior Member

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    Thanks to all for the replies. I kind of, sort of, halfway understand some of it a bit more. One thing - I wasn't even aware there was a LO setting before reading about it here! As I say, it's cold outside, so I never turned the dial down. At least I can see now how to get unheated/uncooled outside air in the warmer months. It appears that the Auto button changes fan speed although it also seems to me that even when I have both Auto and A/C off, a few minutes after I leave my house in the morning, the fan speed jumps up to high for a while all on its own, but I may be wrong about that. In any case, it appears that I don't need either button on to get heat and that's the main thing at this time of year. I'm a bit disappointed in the heater. My feet almost always are colder than my upper body even though I'm only directing air to the lower footwell vents. But I do like being able to set a temperature and let the HVAC take care of it.

    Again, thanks to all.
    John
     
    #9 jhearl, Jan 10, 2014
  10. ztanos

    ztanos All-around Geek!

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    If you hit the defrost button and have it solely on defrost, the fan acts weird, almost as if you hit Auto.
     
    #10 ztanos, Jan 10, 2014
  11. bisco

    bisco cookie crumbler

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    you can shut down the upper vents if they are like the liftback, that will force more air to the feet.
     
    #11 bisco, Jan 10, 2014
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