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A C compressor causing P0AA6 code

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Seymour1, Jul 19, 2024.

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  1. ChapmanF

    ChapmanF Senior Member

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    *starts stopwatch*
     
    #21 ChapmanF, Jul 28, 2024
  2. Seymour1

    Seymour1 Junior Member

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    I cannot find my thread. Did I do something wrong?
     
    #22 Seymour1, Jul 29, 2024
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    This thread? o_O
     
    #23 Mendel Leisk, Jul 29, 2024
  4. ChapmanF

    ChapmanF Senior Member

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    Not that I've noticed...
     
    #24 ChapmanF, Jul 29, 2024
  5. Seymour1

    Seymour1 Junior Member

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    An update:
    I kept wondering how can the high voltage cable, the fuse and the compressor all fail at the same time? So, I replaced the high voltage cable first, then test drove the car. (I noticed that the old cable had been cut by something-maybe it reached the fan blades.) There was no yellow triangle when I drove the car. Then, I plugged in the low voltage plug onto the compressor; no yellow triangle. Then, I installed the fuse and went for a ride; no yellow triangle. Finally, I turned on the A/C switch. Only warm air came out, and I could not hear the compressor running. The fuse did not blow. There is pressure in the system. I quickly opened the schrader valve to test it.
    My next step is to measure and/or add freon.
    I bought a new manifold set, but I used it to add R134A to my 2007 Corolla (non-hybrid). Then, I read a post that warned that if I used the same manifold set on my hybrid, I would contaminate the system with the wrong type of compressor oil. Is this true? If I flush the manifold set cables with acetone or 99% isopropyl alcohol, will that render them clean enough?
    Thanks in advance for assistance.
     
    #25 Seymour1, Aug 11, 2024 at 6:49 PM
  6. ChapmanF

    ChapmanF Senior Member

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    Are there any trouble codes from the HVAC system now? Those are mostly B14xy codes.

    If you haven't got a scan tool that shows them, you can retrieve them without one; look for "Codes from the heat/air conditioning system" toward the end of this page:

    Blink (a/k/a Flash) Codes – How to. | PriusChat

    I don't know that I'd take a chance with a homebrew flushing solution, whether acetone, isopropanol, or what not.

    There are flush regimens that have been used on hybrids when the wrong oil got in (you can search threads here for HECAT), but I don't know if that's anything you could do to a manifold set, for less money than just buying another manifold set to keep dedicated for hybrids.
     
    #26 ChapmanF, Aug 11, 2024 at 7:01 PM
  7. Seymour1

    Seymour1 Junior Member

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    Thanks, Chap
    My Creader-Toyota showed no codes for the A/C. I will order a new manifold set. Since the compressor will not turn on, I do not know what the equalized pressure should be.
    The sight glass looks clear, but I think it means nothing unless the compressor is running.
    There is a pressure switch (I think?) next to the sight glass. If I remove the plug and place an ohmmeter on the 3-pin connector, what should I read? The colors are blue, green and black. Is there another pressure switch for the low side?
     
    #27 Seymour1, Aug 12, 2024 at 12:42 PM
  8. ChapmanF

    ChapmanF Senior Member

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    In the gen 3, that is a pressure transducer, not a pressure switch. So it isn't just ok/not-ok, you can actually read the high-side pressure using a scan tool.

    With the compressor not running, the equalized pressure can be looked up on any R134a "saturation pressure / temperature" chart; given a pressure gauge and the chart, you've got yourself a thermometer. (The temperature that matters is the temperature of the refrigerant and piping in the car, not necessarily the temperature your outdoor thermometer shows.)

    The trouble with the equalized pressure is it doesn't tell you a lot. You will see the same saturation pressure from less than a full charge clear up to more than a full charge, as long as there is enough in the system for any of it to be liquid.

    If you add some more refrigerant, more of it condenses to liquid and you still see the saturation pressure. If you let some out, more of the liquid evaporates, and you see the saturation pressure.

    You'll see a lower pressure only if you are very low on refrigerant—low enough that all is vapor and no liquid remains. So if you see a pressure much lower than the saturation pressure, that does tell you a lot is gone. But once enough has been added to have some liquid again, the pressure will stop telling you much.

    I'm not familiar with Creader-Toyota. Have you checked the HVAC blink codes, just in case that reader doesn't speak HVAC?
     
    #28 ChapmanF, Aug 12, 2024 at 4:29 PM
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