Gen5 PHEV AC intermittently blowing warm during battery cooling

Discussion in 'Gen 5 Prius Care, Maintenance and Troubleshooting' started by p3p5p, Jul 19, 2026.

  1. KMO

    KMO Senior Member

    Joined:
    Apr 15, 2004
    2,029
    751
    0
    Location:
    Finland
    Vehicle:
    2023 Prius Prime
    Model:
    N/A
    Interesting. Next test I'd suggest is max low AC with a cold battery. Can it sustain high power at all? Could be the battery is not really relevant apart from being a long term 'high power' request.
     
  2. LRO

    LRO Member

    Joined:
    Jul 5, 2025
    90
    93
    0
    Location:
    United States
    Vehicle:
    2024 Prius Prime
    Model:
    XSE Premium
    Thank you for finding that magic 104F temp where your Battery ECU made a request for A/C cooling. That's good to know. Closest I've got thus far at 88F ambient is a battery at 96F but some 90+ days coming up this week and if I'm ever in a position to get close to that magic 104F I'll share that.

    So at my cabin 72F cooling my data shows A/C kW consumption never drops to zero. Sure it starts out say at 1 to 2 kW but in a very short time that consumption goes away and settles to a very reasonable .55kW and holds in that vicinity always adjusting. So that's why earlier I couldn't match your description that the cabin air blows cold and then not so cold. I thought it was me not sensing temps like you but in reality it's because the variable-speed compressor is always on and not ever cycling on and off.

    I don't think you'd be delusional in Toyota's eyes to have them look at your vehicle. For one, I don't think when the battery is already at 104F that the A/C should cycle off at all. And although in your test it shows that it was maintaining the battery temp at 104F from 1600-2200 seconds it completely lost control of that once you turned on the A/C in the cabin for yourself (and it still cycled down to zero for no good reason). It'd be quite hard to explain that one away to me especially when your battery temp keeps climbing to 112 F. That's not right.

    Of course, we all put a lot of faith in our OBD adapters and software and hopefully when your unit is reporting 0kW A/C consumption that that's really the case and isn't say anything to do with tracking too many PIDs and not being able to keep up with all that's happening and dropping any data. I can capture ~23 PIDs per second which is less than advertised by OBD adapter marketeers but I am quite aware that with everything important and life-saving communicating on the CAN bus it's absolutely in Toyota's right to not honor every request for PID data that comes along if things are otherwise busy on the network. That said, you earlier kind of prove to me your data has been correct when you don't always feel cool air in the cabin. Toyota engineered this 5th gen HVAC system with a ton of sensors and a neural engine to ensure everything is handled without any discomfort by anyone or anything.