Help with AC Please. 2009 Prius. Blowing not cold air.

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by SunMan, Aug 28, 2019.

  1. SunMan

    SunMan Junior Member

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    Bought it used as a 1st car for my daughter. Had been driving excellent for 4 years and has 185k miles, with original HV battery and a decent 12V battery. AC stopped cooling couple of weeks ago. Had B1443 and B1476. Compressor had stopped. Have static refrigerant pressure 90 psi on high and low sides. Tried to recharge the system with R134a only but system would not suck it in, probably because compressor was shut. Did a lot of research and trials. ultimately got toyota techstream. As soon as hooked the techstream, somehow, without doing anything the compressor came on. But the recharge was still no go, and same 90 psi on both ends. Read somewhere that if you have codes present the system might not come on. So I bit the bullet, despite knowing that its not a good idea, and cleared the codes. But same results. But now I got B1472 and B1474, instead and the compressor is shut. I am sure the the compressor will come back on if I cleared the codes. But I still cannot recharge. This is what I have done so far.

    B1443 - checked the numbers of servo motor with techstream ok. the air is directed as instructed
    Tested the pressure switch. Compressor comes on and off by connecting/disconnecting pin 1 and 4
    coolant pump and fan work. see the coolant flow in the reservoir
    Tested compressor C4 connecter. Have .5 ohms at rest and .7 ohms immediately after shut off
    compressor is not making loud whining noise, but just the usual
    checked r134a pressure with manifold. with on and off same static 90 psi
    micro filter was changed a couple of months ago

    have no other problems or codes
    I do not think the compressor is bad, although I could be wrong
    checked fuse in the cab by the drivers side good.

    did not check the relays or fuses under the hood. do not know which ones to check and for what
    did not check for the fuse in the inverter. do not know if it exists. if someone can verify this
    did not check any other connections, do not know which ones I should

    Is there any way to test the AC part in the inverter, because there is no other problems.

    I do not want to take it to a stealership, because their repair is not guaranteed. They will just keep replacing the parts and keep billing me. Which I could as well, at a fraction of the cost, if I knew where to begin. I have consulted a few local repair shop. When they start talking about the clutch in compressor. I just move on to the next one.

    I can replace the pressure switch, compressor, or the inverter if some experienced person strongly suggests.

    I am fairly mechanically, electronically, and computer inclined. I have done all the work in all of my cars, frontier, 300zx, and odyssey, ever since I had two bad experiences at two different shops, realizing that they do not care about your safety but only money. But have no experience with hybrid AC system. I hope someone can guide me into the right direction. Some of the more experienced users like Patrick Wong, ChapmanF, Britprius, and lech auto air conditionin come to mind, if they can help. I only have a couple of hair left on my scalp. Someone please help. Thanks.
     
  2. Aegean

    Aegean Member

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    Are you sure you got a B1474? For some reason I do not see it in the manual.

    Since the condenser fan comes on, assuming no issues in the engine cooling system, the compressor resistance is fine, and you have not added refrigerant the past 4 years, (not overcharged), it is either the harness between the electric inventer compressor and the AC inverter or unfortunately the AC inverter itself.
     
  3. SunMan

    SunMan Junior Member

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    Thanks for your prompt input Aegean. I was baffled too with B1474. But I promise I currently have both B1472 and B1474. Maybe I will post a picture later, because it will be unbelievable to many readers.

    Yes, I have done the 100-120k maintenance myself with all genuine toyota parts. Engine not overheating, no DTC's. In fact it has been running excellent, and I emphasize. That's a good idea to check the harness, haven't thought about that. I was afraid about the inverter. Is there any process to check/test the inverter?
     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    B1443 just relates to a air outlet damper door. That is a minor problem relative to the bigger one of the air conditioning not functioning.
    B1472 is a malfunction with the A/C inverter. This may be due to the compressor motor.
    B1474 is a malfunction with the A/C inverter.
    B1476 means that the compressor motor is under excessive load because there is too much refrigerant or because the compressor motor is failing.

    Hence I would start by replacing the inverter with a used part from a salvage yard. If that doesn't help the next step would be to replace the compressor. Good luck.
     
  5. SunMan

    SunMan Junior Member

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    Thanks Patrick. Seems like a good plan of action.
    Open inverter cover and test the compressor harness live, being carefully of course, to see if 208V are being fed. Depending on the outcome, replace with a used inverter. If that does not work, then replace with a used/rebuilt compressor.
    But just one concern of the harness test. Even if I see 208V, there will not be any way to test if the inverter is pushing enough amperage. I guess replacing the inverter would be just taking a necessary chance. At least then I would be able to see if there is a slow-blow fuse in there. I will be sure to update this posting. On that note, I wish people would post their ultimate solutions. Give back a little to the community. I have seen so many posts with similar symptoms as mine. Had they updated their posts, there would have been one less posting. Anyway...

    I will update my findings tomorrow or over the weekend, with a photo of the B1474.
     
  6. SunMan

    SunMan Junior Member

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    Here is the update. I'm still alive, apparently. Opened the inverter cover in hopes to find a slow-blow type of fuse and where the compressor wires connect. There is no visible fuse and compressor wires are connected towards the bottom, underneath the the capacitor and circuit boards, so can't get to it to check live voltage. I even tried to check live voltage outside the inverter by disconnecting the C4 connecter and turning the AC on, but of course the system is smart enough to detect the absence of compressor. So no voltage there.

    So I had another idea to test the compressor within the techstream and found that no matter what the target speed I set, the compressor runs at full speed and the rpm's keep getting higher. Is it possible that the inverter is the culprit here and sending full voltage to the compressor, instead of controlled variable. After all the DTS's mention high voltage and inverter. Does someone agree with me. If that is the case can someone with techstream please do me a favor and test the compressor speed to see if the target and the actual rpm's are the same and change accordingly. That would certainly prove that my inverter is bad. I would really appreciate that. Then I will change the inverter. Any idea on where to get one cheaper and good.

    I am attaching photos of the B1472 and B1474 that I got. And by the way I do not get the B1443 and B1476 anymore, even after resetting. Also attaching the compressor test screen photos.
     
    #6 SunMan, Sep 1, 2019
    Last edited: Sep 1, 2019
  7. SunMan

    SunMan Junior Member

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    Here are the photos. Clicked on post instead of add more earlier. No matter what I do, the last 3 photos are turning upside down. Sorry.
     

    Attached Files:

  8. TMR-JWAP

    TMR-JWAP Senior Member

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    I'm curious why your temp setting is max cold but the blower speed is showing as zero? Admittedly, I haven't spent much time using the AC portion of techstream, but I would think the blower fan would need to be running at something other than zero. ANd yeah, the target speed/actual speed issue is a bit unusual. I'll go online with my 2007 this morning and see what it does with similar settings.
     
  9. TMR-JWAP

    TMR-JWAP Senior Member

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    ok, so I went on line with my 2007. Looked to me like the blower fan was the first to start and went to speed 7 before the compressor did anything. But even in auto with MAX COLD, my compressor speed only went into the 5k rpm range.
     

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  10. ChapmanF

    ChapmanF Senior Member

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    If you have a Gen 2, the inverter isn't responsible for just sending voltage to the compressor, it's completely in charge of sending three-phase AC timed waveforms that make the compressor motor spin. If the inverter were to fail in some simple way and just send unmodulated voltage, the compressor would do nothing but sit still and make smoke.

    (That's different from Gen 3, where the compressor really is supplied with straight DC voltage, and makes its own drive waveforms.)

    Perhaps there could still be some inverter problem, but it would have to be something weirder.
     
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  11. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The problem basically is going to be due to the inverter or the compressor. I would replace the inverter first because the target vs. actual RPM is so far off and because it is easier to replace the inverter than the compressor.
     
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  12. SunMan

    SunMan Junior Member

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    Thanks for doing this. But did you run the compressor test or just are looking at the live data by turning the ac on manually? When I run the test, 1st the cooling fan comes on and then the compressor, but never the blower fan. Maybe that's why the blower speed is zero. But when I switch on the ac the blower works just fine.

    I wonder if you do that again and run the test this time.
     
  13. SunMan

    SunMan Junior Member

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    That's what I read, the that inverter is responsible for what speed the compressor should run at depending on humidity and ambient temp and desired temp. So maybe it is just passing thru straight 201V, which runs the compressor at full speed full time, instead of switching between 1 phase and 2 phase. Thanks for replying,
     
  14. SunMan

    SunMan Junior Member

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    Thanks Patrick, that's exactly what is going thru my mind. Found a used inverter on ebay last night for $150 which was taken out from a 2008 and had 115k miles. That is my plan of action, unless there is a better idea.
     
  15. TMR-JWAP

    TMR-JWAP Senior Member

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    You are correct, I just monitored it in real time. I didn't do a compressor test function. IDK that I'll be able to do that this evening. Good to hear that the blower works normally when you turn on the AC.
     
  16. SunMan

    SunMan Junior Member

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    But I can't stop scratching my head as to why it is showing me the static pressure of 90 PSI and why not the actual low and high pressure. And why it would not let me overcharge even if there is enough refrigerant in there. Could bad inverter cause that? Or is really the compressor? I could imagine some blockage in the pathway but it should still show the working pressure and not the static pressure. Any thoughts on that?
     
  17. SunMan

    SunMan Junior Member

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    I'd appreciate whenever you can do it. Thanks.
     
  18. TMR-JWAP

    TMR-JWAP Senior Member

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    I thought I read somewhere that the AC Amplifier was responsible for determining desired compressor speed. That item is also listed as a possible culprit in your codes.

    As for the 201vdc thing, I don't think this is possible. The inverter turn's the constant voltage DC into a 3 phase AC waveform to run the motor. Your photos show at one point the AC compressor was at 10k+ rpm? I have a hard time believing that was a true speed. Seems like discharge pressures would be crazy high. Motor shaft broken?

    but, the codes you have definitely seem to point to an inverter issue.
     
  19. SunMan

    SunMan Junior Member

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    And you are absolutely correct of the amplifier's function. I might be mixing my readings. I have read so much in the past couple of weeks, it reminded me of my school day.

    I have seen it reach 11K as well and still climbing up. And that's why I am having hard time choosing the 1st part to replace.
     
  20. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    That’s crossed my mind more than once, reading through this thread. I don’t expect the inverter knows how to handle an unloaded motor, so it’s just getting itself into trouble and false codes. Combined with pressure readings that don’t budge? Yeah, I think the compressor gubbins have separated from the motor.

    Does techstream show A/C current load anywhere? Can you guys compare the draw on a healthy car to the victim? If the vic is doing 10k+RPM drawing 2 amps while the healthy one is pulling 30 amps, that would shore up the case for the busted motor shaft...
     
    #20 Leadfoot J. McCoalroller, Sep 2, 2019
    Last edited: Sep 2, 2019
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