A/CBlowing Hot Air Error code DTC B1471 AC inverter High Voltage

Discussion in 'Prius v Care, Maintenance and Troubleshooting' started by Tarek, Mar 17, 2025.

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  1. Tarek

    Tarek Junior Member

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    HI everyone
    i had 225000 Mil 2012 Prius V and after successful DIY JDM 3rd GEN engine replacement all is working fine
    but THE A/C is not blowing cold air. so also when I checked with code on without scaning tool like I got the
    code 71.
    after some research I found that
    DTC B1471 A/C Inverter High Voltage Power Resource Sys- tem Malfunction
    DESCRIPTION

    The A/C inverter monitors the power voltage from the main battery in the self circuit. It stops compressor control and outputs the DTC when the monitored voltage is outside the specified range.
    The output DTC is memorized as previous trouble. Compressor control may not resume unless the power switch is turned OFF.

    HINT:
    The hybrid control system and air conditioning system output DTCs separately. Inspect DTCs following the flowchart for the hybrid control system first if any DTCs from those systems are output simultaneously.

    DTC No. Detection Condition

    B1471 Open or short in A/C inverter high voltage power resource system

    Trouble Area

    • Hybrid control ECU
    • A/C inverter (inverter with converter)

    so any advice
    or how can I start Diagnoses

    everything looks ok to me, yes maybe is the A/C Compressor need to be replace but how about if there is something else is making the compressor to blow up again.

    I still have refrigerant but i can measure it but it is still there.
    help is appreciated
     
    #1 Tarek, Mar 17, 2025
  2. MAX2

    MAX2 Senior Member

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    Have you checked the fuse in the inverter that supplies power to the compressor? This should be done with the machine turned off, taking all high voltage precautions.

     
    #2 MAX2, Mar 17, 2025
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  3. Tarek

    Tarek Junior Member

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    Yes I did check the this High voltage fuse by the multi meter and is still connected.
    ok what I remember that i did wrong : before working on the car and replace the engine by mistack i removed the positive side only of the 12 V battery and i kept the Negative side on.
    in addition I pulled the orange safety plug but I never removed completely which still has some connection
    well you might also ask if i removed The AC orange Hi voltage plug for AC compressor i would say no I did not.
    so please folks out there out there disconnect the AC compressor next time for such a job
     
    #3 Tarek, Mar 17, 2025
  4. Joele3

    Joele3 Active Member

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    I had this problem. Ended up being coolant splashed inside AC connector. Sits right on top. I plugged in and it threw a code. May have shorted the AC. I tried cleaning the pins and ended up breaking one. So now anytime I work on the car I put tape over the AC connector. I ended up replacing the AC unit.
     
    #4 Joele3, Mar 17, 2025
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  5. Tarek

    Tarek Junior Member

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    #5 Tarek, Mar 17, 2025
  6. Tarek

    Tarek Junior Member

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    IMG_3489.jpg it's worth to mention that with the first scan I found P0AA6 But I cleared the code and never came back but only the B1471 code
     
    #6 Tarek, Mar 17, 2025
  7. ChapmanF

    ChapmanF Senior Member

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    It's possible there was some leakage through the high-voltage insulation at first, enough to set P0AA6, that was later enough to let some magic smoke out and produce B1471.

    You're positive of your test of the fuse in the inverter?
     
    #7 ChapmanF, Mar 17, 2025
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  8. Tarek

    Tarek Junior Member

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    I was hoping that the fuse was the issue, but the used Multimeter and very connected side to side and the zero shows up which is indicated to be connected. Yes Positive
     
    #8 Tarek, Mar 17, 2025
  9. Tarek

    Tarek Junior Member

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    does any one know where is the AC compressor relay on the box fro 3rd Gen ?
     

    Attached Files:

    #9 Tarek, Mar 17, 2025
  10. ChapmanF

    ChapmanF Senior Member

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    What makes you think there is an AC compressor relay?

    The compressor gets 200+ VDC power at all times when the car is in READY, over the big orange cables. The only relays involved are the big ones in back cutting off the traction battery from the whole car. Low-voltage control signals from the A/C amplifier tell the compressor when and how fast to run.
     
    #10 ChapmanF, Mar 17, 2025
  11. MAX2

    MAX2 Senior Member

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    Current leak P0AA6 is a serious error, you did not pay enough attention to it, focusing on other minor errors. If you have the opportunity to scan again with Techstream, then do it. There is a freeze frame on frozen errors, it would be great if the data was posted in the topic and you could be helped to understand the reasons for their occurrence.
     
    #11 MAX2, Mar 18, 2025
  12. MAX2

    MAX2 Senior Member

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    It is also necessary to check the condition of the wiring to the air conditioning compressor for short circuits and open circuits.
    CAUTION:
    Be sure to wear insulated gloves.
    1. Disconnect the No. 2 engine wire connector.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection       Condition Specified Condition
      E1-1 (PE) - E2-2 (ACPE) Always Below 1 Ω
      E1-2 (PB) - E2-1 (ACPB) Always Below 1 Ω
      E1-1 (PE) - Body ground Always 10 kΩ or higher
      E1-2 (PB) - Body ground Always 10 kΩ or higher
     
    #12 MAX2, Mar 18, 2025
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  13. Tarek

    Tarek Junior Member

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    its one of possibility, but not sure how to check a relay. i switched with another one who look the same but nothing change
     
    #13 Tarek, Mar 18, 2025
  14. ChapmanF

    ChapmanF Senior Member

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    If you are looking for an A/C relay, you are looking for something the car does not have.

    The power to the A/C compressor is supplied at all times the car shows READY on the dash.

    The only relays even involved are the system main relays in the rear, and if they did not operate properly, the car could not be started or driven at all.
     
    #14 ChapmanF, Mar 18, 2025
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  15. Tarek

    Tarek Junior Member

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    the reason that I Ignored it that after I cleared the codes. I scanned almost 6-10 times in the last week after few hundreds miles driving, and never show up again. so P0AA6 never show up again since the first scanning ever. only B1471.
     
    #15 Tarek, Mar 18, 2025
  16. ChapmanF

    ChapmanF Senior Member

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    An insulation leak such as P0AA6 reports can sometimes become enough of a leak to conduct short-circuit current and damage something else. Then you might have only a code like B1471 reflecting that damage, and not P0AA6 anymore.

    Or there might just be some physical damage to, for example, the orange power cable from the inverter to the compressor, that under different circumstances could manifest as a P0AA6 (if leaking to body ground) or B1471 (if just not conducting well).
     
    #16 ChapmanF, Mar 18, 2025
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  17. Tarek

    Tarek Junior Member

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    so How can I diagnoses it ?
     
    #17 Tarek, Mar 18, 2025
  18. Tarek

    Tarek Junior Member

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    Today I did some diagnoses :
    1- I end up unplug the the AC compressor (non Orange ) and check with tech smart still getting the P1471
    2- now unplug both 12 V and the Orange that comes from the inverter than scan again the old P1417 disappeared than i got B1498 (communication malfunction ( A/c Inverter local)
    3- connected both i only got back and scan again i got only P1471 back
    4- check the high voltage fuse with continuity with multimeter and still in good condition

    I notice that there is some activity on the line there is some Air bubbles but of course the compressor not engaging

    if I am not mistaking it sounds like compressor is gone and need a replacement
     

    Attached Files:

    #18 Tarek, Mar 18, 2025
    Last edited: Mar 18, 2025
  19. MAX2

    MAX2 Senior Member

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    P1417?

    Or is it still B1471?

    What activity can there be if the compressor does not turn on?
    Have you checked the wiring and connectors as indicated in post #12?
     
    #19 MAX2, Mar 18, 2025
  20. Tarek

    Tarek Junior Member

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    I belief you are talking about this

    CAUTION:
    Be sure to wear insulated gloves.
    1. Disconnect the No. 2 engine wire connector.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection       Condition Specified Condition
      E1-1 (PE) - E2-2 (ACPE) Always Below 1 Ω
      E1-2 (PB) - E2-1 (ACPB) Always Below 1 Ω
      E1-1 (PE) - Body ground Always 10 kΩ or higher
      E1-2 (PB) - Body ground Always 10 kΩ or higher

    no I forgot, but to confirm the 12 v battery will remain connect as well as the orange plug . but not sure if the car needs to be on or off. and how about the ac status on or OFF
    the plug has 4 pins but not sure which is which I am searching a little about this
     
    #20 Tarek, Mar 18, 2025
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