1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Auto mode for heat & A/C question

Discussion in 'Gen 3 Prius Main Forum' started by 4rpr15, Oct 1, 2015.

  1. 4rpr15

    4rpr15 Senior Member

    Joined:
    Jul 16, 2015
    1,056
    375
    0
    Location:
    WI
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    Here in the Midwest its starting to get cold, very cold.... so the heat is getting cranked. Why doesn't Auto mode leave it on the heat setting when I leave and come back? It reverts it back to A/C.

    MotoG3 ?
     
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,781
    48,987
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    is it warm in the car? i assume it's using a/c to bring the temp down to your setting.
     
  3. Tideland Prius

    Tideland Prius Moderator of the North
    Staff Member

    Joined:
    Oct 2, 2004
    44,837
    16,073
    41
    Location:
    Canada
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    What's your temperature setting and what temperature range are you seeing outside?
     
  4. JTM2955

    JTM2955 Active Member

    Joined:
    Feb 8, 2015
    475
    185
    0
    Vehicle:
    2004 Prius
    Its supposed to work like that. If it kicks on the A/C, its getting input from the solar sensor on the dashboard. That sensor is a photovoltaic cell that tells the Auto AC to run the compressor for a bit. When the target temp is reached, the compressor is turned off. No big deal, usually when you turn on the defroster, the compressor is engaged to knock the humidity out of the air going to the windshield.

    I have seen condensation appear after the car sits outside and the temp changes. Thankfully, most systems do this for faster windshield clearing. Note: you should not leave this in the defrost position, it will use more fuel do to theengine running more often.
     
    WilDavis likes this.
  5. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,781
    48,987
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    if it's freezing inside the car, condensation could freeze to the inside of your windshield, making visibility a health hazard.
     
    JTM2955 likes this.
  6. 4rpr15

    4rpr15 Senior Member

    Joined:
    Jul 16, 2015
    1,056
    375
    0
    Location:
    WI
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    Not quite.

    MotoG3 ?
     
  7. 4rpr15

    4rpr15 Senior Member

    Joined:
    Jul 16, 2015
    1,056
    375
    0
    Location:
    WI
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    76 is the setting. 55 outside.

    MotoG3 ?
     
  8. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,781
    48,987
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    must be the condensation.
     
  9. 4rpr15

    4rpr15 Senior Member

    Joined:
    Jul 16, 2015
    1,056
    375
    0
    Location:
    WI
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    Meaning the A/C will automatically shut off while I'm driving?

    MotoG3 ?
     
  10. 4rpr15

    4rpr15 Senior Member

    Joined:
    Jul 16, 2015
    1,056
    375
    0
    Location:
    WI
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    There was no visible condensation.

    MotoG3 ?
     
  11. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,781
    48,987
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    you may need to have the dealer take a look.
     
  12. 4rpr15

    4rpr15 Senior Member

    Joined:
    Jul 16, 2015
    1,056
    375
    0
    Location:
    WI
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    The heat and A/C work fine when I set them manually. The A/C works great in auto mode, I guess the heat mode setting will take a bit to get used to in Auto mode.

    MotoG3 ?
     
  13. JTM2955

    JTM2955 Active Member

    Joined:
    Feb 8, 2015
    475
    185
    0
    Vehicle:
    2004 Prius
    I don't know how many times I have seen drivers with the frost on the INSIDE of the car.
    You should never use RECIRCULATION during the winter. Your warm humid air you breathe in and out cause a build up of humidity in the car's interior.

    If they would simply move the air lever to fresh their problem would be solved. You know you have a problem when you see these guys scrapping the inside of their windshield.
     
    bisco likes this.
  14. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,781
    48,987
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    good point. this is especially true in high humididity.
     
  15. 4rpr15

    4rpr15 Senior Member

    Joined:
    Jul 16, 2015
    1,056
    375
    0
    Location:
    WI
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    I have never used that.

    MotoG3 ?
     
  16. JTM2955

    JTM2955 Active Member

    Joined:
    Feb 8, 2015
    475
    185
    0
    Vehicle:
    2004 Prius
    Yes or it will cycle so minimally it will be almost unnoticed. Indeed, unless you go to the A/C button and manually turn it off.
     
  17. WilDavis

    WilDavis Senior Member

    Joined:
    Feb 4, 2014
    2,489
    2,153
    49
    Location:
    Top RH Corner of RH Coast on L side of The Pond
    Vehicle:
    2009 Prius
    Model:
    II
    Yup, I've noticed mine choosing the setting of the "recycle/no-recycle" vent depending on the wx conditions outside - I let it do its own thing, and it seems to manage pretty well without me poking my nose in! ;)
     
    4rpr15 likes this.
  18. 4rpr15

    4rpr15 Senior Member

    Joined:
    Jul 16, 2015
    1,056
    375
    0
    Location:
    WI
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    So even in Auto Mode I will need to manually shut the A/C off? I would think it should do that on its own. I'll test it in the morning. My Prius is garage parked so I can't see it starting up with the A/C in the morning.

    MotoG3 ?
     
  19. 4rpr15

    4rpr15 Senior Member

    Joined:
    Jul 16, 2015
    1,056
    375
    0
    Location:
    WI
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    So set the temp, press Auto mode and leave it?

    MotoG3 ?
     
  20. JTM2955

    JTM2955 Active Member

    Joined:
    Feb 8, 2015
    475
    185
    0
    Vehicle:
    2004 Prius
    Right, it does take some getting used to. Just set it to your comfortable temp and forgetaboutit.

    I have mine set at 71 practically all the time. If I get cold, I might raise it to 75. If my wife rides with me, she will raise it to but I turn it down after she loses her chill.

    Also, don't worry if you start your car and the Auto AC does not work immediately. It does sense when the coolant temp is high enough to not cause a cold draft of air. Nicely thought out.
     
    4rpr15 likes this.