B1476 AC Compressor Not Working - seeking sage advice

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Chicago David, Jul 5, 2026.

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  1. Chicago David

    Chicago David Junior Member

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    Hola All! Our trusty 2005 Gen2 is blowing hot air w/ AC set to Max Cold - read all of the other posts, looking for a few additional opinions
    • Fuses and relays are good
    • Cleaned the pressure valve connections
    • Condenser fan spins when AC turns on, runs for a few seconds and stops
    • Originally thought the compressor wouldn’t kick on due to low 134a, low side was about 55 psi with the compressor not working which calculates out to a little low
    • Added some 134a and the low-side pressure is around 85 psi which seems right with the compressor not kicking on and the ambient temperatiure
    Both B1476 history and live DTCs are showing along w/ the B1421 (but it was very cloudy out today and I could clear the code sometimes).

    Is it time to buy an OEM compressor or is there anything else I should check or do?

    Thanks Community!
     
    #1 Chicago David, Jul 5, 2026
  2. Tombukt2

    Tombukt2 Senior Member

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    So what's the problem when you put the air condition on LO not a temp . And hi fan . If you get out and touch the big fat silver hose and it's coooold. You're . Making the cycle . Because it's not making it into the car is another situation . So we're we at here?
     
    #2 Tombukt2, Jul 6, 2026
  3. ChapmanF

    ChapmanF Senior Member

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    The repair manual section for B1476 pretty much tells it like it is. The electrical power drawn by the compressor in operation is being measured too low or too high for the conditions. It can be too low if there's not enough refrigerant. It can be too high if there's too much refrigerant, or if the compressor is failing and hard to turn.

    It's up to the human to figure out which of those possibilities it is, then fix.
     
    #3 ChapmanF, Jul 6, 2026
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  4. Chicago David

    Chicago David Junior Member

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    Thanks - tried running it not on “auto” with fan on HIGH but the temp higher (72 degrees instead of MAX COLD). The silver hose is not cold on either side of the valve and still not hearing the compressor doing its thing.

    Could not tell if the radiator fans were spinning up this time though because I was by myself.

    Thoughts?
     
    #4 Chicago David, Jul 10, 2026
  5. Tombukt2

    Tombukt2 Senior Member

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    No temp we want lo we want the compressor running wide open not some number that you decide you want to set because it's above something you think we're trying to get past you're thinking.. so if you don't hear the compressor doing its thing set like I'm talking about then more than likely you don't have enough gas in the system for the system to recognize and turn on the compressor for simple enough. Most AC systems are built this way your house your car window unit etc . No gas present means nothing is going to run it's a safety feature
     
    #5 Tombukt2, Jul 11, 2026
  6. BiomedO1

    BiomedO1 Senior Member

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    You shouldn't just randomly fire freon into a variable speed compressor setup. The system needs to be evacuated and the correct amount of freon needs to be injected into the system (by weight, NOT by pressure). You can't just go by pressure readings, without doing a bunch of calculations, which would include the current rotational speed/displacement of the compressor.
    The error code is telling you that the compressor can't turn so:
    1. you've got a defective compressor.
    2. it's not getting enough power.
    3. freon pressure is too high or low and the safeties are cutting in.

    You need to test to see what your actual problem is and rectify it - or you can just keep groping around in the dark, firing the parts cannon at it and hope you get lucky.

    YMMV
     
    #6 BiomedO1, Jul 11, 2026
    Last edited: Jul 11, 2026
  7. ChapmanF

    ChapmanF Senior Member

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    Well, the code is telling you that the electrical power drawn by the compressor in operation is being measured too low or too high for the conditions. It can be too low if there's not enough refrigerant. It can be too high if there's too much refrigerant, or if the compressor is failing and hard to turn.

    It's up to the human to figure out which of those possibilities it is, then fix.
     
    #7 ChapmanF, Jul 11, 2026
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  8. Chicago David

    Chicago David Junior Member

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    Thanks to ChapmanF | PriusChat, https://priuschat.com/members/biomedo1.191647/, and Tombukt2 | PriusChat for the input!

    So I was able to get better diagnostic tools with an ICON ODB2 rig and more detail. Update:

    - Cabin blower fan, touch panel controls, and system doors (like switching from exterior to interior air) all work as expected.
    - Radiator fans work perfectly
    - The compressor does try to kick on but rpm’s don’t get to the target (1.1k vs. 5k)
    - The radiator / condenser fans kick on, then the compressor tries to kick on, but the compressor makes a motor-boating brrrrrr sound for a few seconds then stops - then tries again then stops - and then gives up trying

    The next best step seem to be to take it to a friendly garage to have the refrigerant taken out, a vacuum test done, and then to refill the system with the exact amount of 134a.

    Or - is the motor-boating sound an indicator that the compressor has seen its better days and I should move straight replacing the compressor?

    Looking forward to feedback - thx!
     
    #8 Chicago David, Jul 12, 2026 at 4:36 PM
    Last edited: Jul 12, 2026 at 9:30 PM
  9. Tombukt2

    Tombukt2 Senior Member

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    No man it's time to just get a compressor sounds like to me ..
     
    #9 Tombukt2, Jul 12, 2026 at 10:53 PM
  10. Chicago David

    Chicago David Junior Member

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    thanks - next round of questions if a new compressor is required:
    - Are any of the Rock Auto OEM compressors acceptable?
    - They all come pre-loaded with the insulating lube, is this sufficient for the install and to get the system going?
    - Is a new O ring kit, or anything else required to do this right?
    - Could I have a trusted shop vacuum out the 134a and do a test - then I do the swap out - and then they recharge the system with the exact amount - OR - should I just pay the big bucks and have them do it so I have a warranty?

    Thanks!
     
    #10 Chicago David, Jul 18, 2026 at 1:43 PM
  11. Tombukt2

    Tombukt2 Senior Member

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    Most pumps are going to ship with some oil there's also residual oil left in the piping in bends in you're system . Just bolt it up connect up the hoses use your $60 pump plugged into an outlet connected to a set of gauges and vac for hour close all systems and let fit for an hour gauges still same numbers?? ?. If so. Get ready to add gas to system one full complete can and two or three shots out of another then save the rest on you're gauge set. Top off mom or the neighbor or somebody
     
    #11 Tombukt2, Jul 18, 2026 at 2:59 PM
  12. Chicago David

    Chicago David Junior Member

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    Thanks - I do not yet have a pump and gauge kit yet. I just have the filler gauge for the low side. I’m all for buying a kit and saving the $. Two questions:
    1-Is there a kit you’d recommend which I can use to pull out and store what’s in there?
    2-Or, what do I do with what’s in there now? I don’t really want to deplete the ozone anymore that it is already. ; - )

    Maybe this kit from Amazon (sorry couldn't seem to paste in the link):
    VIVOHOME 110V 1/4 HP 3.5CFM Single Stage Rotary Vane Air Vacuum Pump and AC Manifold Gauge Set Kit with Thermometer for R134a R12 R22 R502 R410a HVAC Air Conditioning Refrigeration Recharging

    And this compressor: More Information for FOUR SEASONS 6685NK

    And I’m assuming I can skip the new valve and condenser?
     
    #12 Chicago David, Jul 18, 2026 at 3:24 PM
    Last edited: Jul 18, 2026 at 3:45 PM
  13. Tombukt2

    Tombukt2 Senior Member

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    You're pumping gauge you're going to have nothing to do with what's released into the atmosphere. The little bit of gas discussed here is hardly worth buying re over equipment for . The idiot mechanic at home doesn't get fine $40,000 for this stuff all old wives tales .
     
    #13 Tombukt2, Jul 18, 2026 at 6:31 PM
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