Car keeps asking if A/C can be used

Discussion in 'Prime Plug-in Charging' started by iskoos, Oct 18, 2025 at 10:29 AM.

  1. iskoos

    iskoos Active Member

    Joined:
    Dec 24, 2017
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    Location:
    Orlando, FL
    Vehicle:
    2010 Prius
    Model:
    III
    My Prime keeps asking me if the A/C can be used during the charging.
    I was ignoring this at first. Then I wanted to say yes to avoid the question.
    But it didn't help at all. It still asks me the same and I say "Yes" almost every time.
    Yet, I have never seen it run the A/C during the charging.

    What's the purpose of this question?
     
  2. BiomedO1

    BiomedO1 Senior Member

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    Location:
    SacTown, Ca
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    I'm assuming you have a gen4 Prime (air cooled traction pack) not a gen5, since those are cooled differently
    The traction pack cooling air is pulled from the car's passenger cabin. If you like it hot in your car, the traction pack has a harder time cooling itself down and will slow down charging if it gets too warm.
    The AC doesn't kick-on until the car is ready to charge the traction battery. So if your on a charging schedule, you won't see the AC kick-on. Before charging begins, the ECU will turn-on your AC unit to cool the interior of the car, so it can cool down the traction pack while it charges.

    Hope this helps.....
     
  3. iskoos

    iskoos Active Member

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    Location:
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    Vehicle:
    2010 Prius
    Model:
    III
    Oh yes, mine is 2017 Gen4 Prime. And yes, I like it hot. I rarely use the A/C and it is hot down here in Florida. I do understand how the cooling system works for the A/C. I know that it gets air from the cabin. My issue was that even though I was saying "Yes" to the question, the car would never turn the air on while charging. I have never witnessed this even once.
    But now I am thinking more and maybe my answer has a time out. Because I plug in my car once a week and I never do it immediately after I park. I let the battery cool off first.
    I am thinking now that that must be the reason. The car is asking me if the A/C could be used. I say "Yes" but I never charge it immediately and my answer either gets timed out or by the time I charge my car the battery is cooled off enough that the car doesn't need the A/C anymore.
    Gotta be one of these.

    But I was told (or read here somewhere) that the Gen4 cannot charge and use the A/C at the same time. People were complaining about this. And I think I tried this myself once also. I was unable to turn on the A/C while the car was plugged in.
    How this feature is going to work still puzzles me. I would love to hear it from those who successfully used it.
     
  4. BiomedO1

    BiomedO1 Senior Member

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    Location:
    SacTown, Ca
    Vehicle:
    2021 Prius Prime
    Model:
    LE
    The electronic AC compressor is driven by the traction battery, NOT the charging cord. The car won't charge and run the AC at the same time. It does one or the other.
    The experiment I used - top-off the traction battery then run the car's preconditioning (10 minutes; cool down the car) while still plugged-in. The traction battery will NOT be full after the 10 minute cooling cycle and the battery pack will start recharging after AC shutdown. Vicious cycle, wait till the battery is fully recharged again and the cabin is hot again or take-off with a partially full battery....:(:mad::eek::whistle: