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Gen2 AC code 23 and 21 and HVAC issues

Discussion in 'Gen 2 Prius Technical Discussion' started by Marigold2, Jun 18, 2024.

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  1. Marigold2

    Marigold2 New Member

    Joined:
    Jun 18, 2024
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    Location:
    Wisconsin
    Vehicle:
    2009 Prius
    Model:
    Two
    I have been having AC issues with my 2009 Prius since last summer. The warning triangle and coolant light have been coming on and going off intermittently while driving. As in it happens only sometimes when I drive and can be days to weeks apart. I have had no air conditioning and no heat and have been trying to get this issue addressed since June 2023.

    I had a lot ($3k worth) of repairs done by the dealer and the problem was not corrected and I gave up on those mechanics. I went to my local mechanic and he found that one of the hose clamps was completely corroded at the throttle body and the system was not holding pressure. He replaced the clamp, rechecked the pressure, and then added some stop leak and rechecked the pressure held overnight. I actually had heat for a whole day after that and then not again.

    With the current heatwave the lights have returned as I turn on the A/C to get the fan at least.
    I've checked the diagnostic codes over the past week and get code 23 most often, 21 on occasion.

    What do these codes mean and does anyone have the roadmap for the Gen2 HVAC system and wiring diagram?

    At this point I'm ready to see if I can fix it myself.
    I've heard that the HVAC for the Gen2 is really quirky. Other than that the car runs well and I would love it to last for another 100k miles (it's at 320k now),

    The dealer repaired the following from JUN-JUL2023:
    upload_2024-6-18_12-35-22.png
    upload_2024-6-18_12-37-18.png
    upload_2024-6-18_12-37-38.png
    23Jun2023
    upload_2024-6-18_12-38-10.png
    03JUL2023
    upload_2024-6-18_12-39-29.png
     
    #1 Marigold2, Jun 18, 2024
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  2. Tombukt2

    Tombukt2 Senior Member

    Joined:
    Nov 29, 2020
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    Location:
    Durham NC
    Vehicle:
    2009 Prius
    Model:
    Base
    By looking at this receipts you've had a lot of work done to this car AC condensers I mean it's list is pretty extensive and this car is in pretty good shape we're saying interesting The heat and all of that sort of thing is probably related to the coolant issues that have been going on and may not have been fixed correctly I don't know. The air conditioner is not hugely quirky where are you going to start? You have gauges a low side gauge when you connect your can with the gauge on it and the car running and the air conditioner on and everything what's that gauge say on top of the can? That's a good place to start when you flip the air conditioning on do you hear the compressor running It's electric so it sounds funny in this car It's not the normal belt around the clutch affair like in the Chevrolet.
     
    #2 Tombukt2, Jun 18, 2024
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  3. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
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    16,209
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    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Don't sweat the 21: that's a non-problem with the dash solar sensor, as you can read about toward the end of the page here:

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

    The 23, I believe, is about the signal from the A/C pressure switch ... which can mean there's the wrong amount of refrigerant to get the right pressure ... or something wrong with the switch, or the wires to it.
     
    #3 ChapmanF, Jun 18, 2024
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