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

AC doing its own thing

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by macmaster05, Jan 24, 2018.

  1. macmaster05

    macmaster05 Senor Member

    Joined:
    Sep 27, 2009
    4,050
    728
    5
    Location:
    USA
    Vehicle:
    2010 Prius
    Model:
    Two
    In morning when I turn on my heater I set the fan to blow forward and fan level of 1, to save energy. After a few minutes though, the fan always ramps up to level 4 or 5 and the system switches to AUTO. When I turn AUTO off and turn the fan back down, the fan sets to blow at my feet. It's incredibly annoying and I'm not sure why it's doing this. How can I make this stop? Anybody else have this issue?
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,710
    38,247
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    You turn AUTO "off", by overriding something, specifically mode or fan speed, correct?

    upload_2018-1-24_9-2-17.png
     
  3. macmaster05

    macmaster05 Senor Member

    Joined:
    Sep 27, 2009
    4,050
    728
    5
    Location:
    USA
    Vehicle:
    2010 Prius
    Model:
    Two
    Can't actually remember. I think I usually press AUTO to turn it off, because I think pressing any of the other buttons first won't do anything. I might be wrong though.

    But if I have AUTO off and everything set to my liking, its not supposed to suddenly turn on when the car feels like it, right?
     
  4. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,710
    38,247
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    I think the AUTO button's only function is to activate auto mode, not turn it on/off?
     
  5. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,710
    38,247
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    What I miss, and I'm not sure maybe it is in there somewhere, if I've got some settings, some overrides, say both mode and fan speed, if I push the "OFF" button, the only way to get back there is to push "AUTO", and then reset all my overrides. In other words, the only way to turn the system back on is to set it AUTO mode.

    I've got a vague recollection that if I had overrides, pushed "OFF" and then pushed a special button, maybe fan speed up, it would wake up the system, with all my previous settings. But I'm suspecting it's my flakey memory, that's in fact with our previous Civic.
     
  6. macmaster05

    macmaster05 Senor Member

    Joined:
    Sep 27, 2009
    4,050
    728
    5
    Location:
    USA
    Vehicle:
    2010 Prius
    Model:
    Two
    Oh right, I'm sorry. I press OFF to turn AUTO off. Forgot about that button, heh.

    I believe I can turn on the A/C by pressing the fan level up. That's what I've always done. And if that's the case, that still doesn't answer why Auto turns on though...?
     
  7. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,710
    38,247
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Wait a sec though: OFF doesn't just turn AUTO off, it turns everything off.

    Having done that, if you subsequently push the fan speed up button, what happens? I'm stumped. :oops:
     
  8. macmaster05

    macmaster05 Senor Member

    Joined:
    Sep 27, 2009
    4,050
    728
    5
    Location:
    USA
    Vehicle:
    2010 Prius
    Model:
    Two
    Yes, but then I have to turn the fan back on. The process doesn't seem to repeat, as it stays at my settings, but not after going through that whole workaround.
     
    Mendel Leisk likes this.
  9. danlatu

    danlatu Senior Member

    Joined:
    Apr 27, 2017
    533
    1,346
    2
    Location:
    maryland
    Vehicle:
    2011 Prius
    Model:
    Two
    Is your compressor working? Mine did weird things before it crapped out @ 302k throwing a check hybrid system code. It rained and I had no a/c. The windows fogged up so bad and was dangerous to drive. Luckily I was able to install a used a/c compressor (55k miles on it/ebay), new condenser/dryer, 2.5 cans of r134, new hybrid compressor oil all for 166$ and my time. I know the dealer wants $$$$:mad::mad::mad::mad:. I have a vacuum pump and gauges at home and was lucky enough to use techstream to bypass the used compressor to suck the new refrigerant in. Thank god for auto shop class and kevin here on priuschat. These prices below from the dealer do not include refrigerant, hybrid compressor oil or labor. I will never go to the stealership. Whenever a compressor is replaced you have to replace the condensor and dryer per manual.
    Screen Shot 2018-01-24 at 6.03.38 PM.png
     
    #9 danlatu, Jan 24, 2018
    Last edited: Jan 24, 2018
  10. macmaster05

    macmaster05 Senor Member

    Joined:
    Sep 27, 2009
    4,050
    728
    5
    Location:
    USA
    Vehicle:
    2010 Prius
    Model:
    Two
    I appreciate the insight. Do you know how to check the health of a compressor? (Without taking the car apart)
     
  11. danlatu

    danlatu Senior Member

    Joined:
    Apr 27, 2017
    533
    1,346
    2
    Location:
    maryland
    Vehicle:
    2011 Prius
    Model:
    Two
    I did an ohm reading to ground and had a fault. You will need techstream software and a windows 32 laptop to further trouble shoot your problem. You could have a bad control/'computer right above the gear shifter. In the techstream you can override the fan speed, compressor speed, pretty much all the controls on the console to isolate your problem. I would also try unplug and replug all your wiring harness' from the back of the ac controller. You could have a loose wire.
    I know how to check to see if the compressor is low on charge with gauges. You also have a small sight glass by your coolant reservoir. It should be clear with very few bubbles when the compressor and interior fan are at full speed. Slower flow with a little bit more bubbles when ac compressor is low. Is any cold (split difference) air coming out of your vents when a/c is on.
    Screen Shot 2018-01-24 at 8.04.46 PM.png
     

    Attached Files:

    #11 danlatu, Jan 24, 2018
    Last edited: Jan 24, 2018
    Grit likes this.
  12. CR94

    CR94 Senior Member

    Joined:
    Dec 2, 2014
    2,642
    1,134
    0
    Location:
    Northwestern S.C.
    Vehicle:
    2011 Prius
    Model:
    Two
    Then the fan runs at the speed you manually set and mode (air outlet option) remains automatic or remains manual, whichever it was before you hit OFF. Temperature also remains as it was.
    It's a confusing system, even after you've learned most of its tricks.
     
  13. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,710
    38,247
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Yeah must have been our previous Civic. Hitting fan speed up turned it back on, with all previous overrides. Saved a tedious chore of hitting auto to activate, then doing overrides one at a time. That setup really discourages anything but auto. I usually go with it but hey.