Gen 3 AC issue - short cycling

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Otispunkmeyer, Jul 26, 2018.

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  1. Otispunkmeyer

    Otispunkmeyer New Member

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    Jul 23, 2018
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    Location:
    Loughborough UK
    Vehicle:
    2009 Prius
    Model:
    Excel
    Ok so bit of a problem with the AC.

    Background: used Prius just bought from independent used car dealer. AC didn't work on test drive. I asked them to regas. They did and when I picked it up it was working.

    FFWD to now: It's been very hot and the AC has not worked during the hottest parts of the day. It seems to work fine in the morning when it is cooler however. Though it's still not great.

    Symptoms: Hit the AC button and...

    1) lights on the recirc/outside air buttons cycle between each other.

    2) condenser fans spin up. Shortly followed by compressor spinning up.

    3)almost immediately after that, both items shut off.

    4)steps 2&3 repeat until you've had enough. Sometimes you'll get a longer cycle than the others up to a minute or so. Then it's back to short cycling.

    When the AC does work it blows cold but I wouldn't say it's ice cold. It's also a little damp/musty feeling. That should be fixable with a new cabin filter and perhaps a condenser foam clean.

    What is causing the cycling though?

    Here's a link to some video:

    (Will post when I've met the requirements to post links).
     
    #1 Otispunkmeyer, Jul 26, 2018
  2. ASRDogman

    ASRDogman Senior Member

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    Sounds like you are low on freon. There's probably a leak since there was no freon when you test drove it.
    It's a sealed system, so if it's empty, there IS a leak.
     
    #2 ASRDogman, Aug 1, 2018
  3. ChapmanF

    ChapmanF Senior Member

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    Model:
    IV
    Too much refrigerant could also cause short cycling, via the high pressure limit. Other things could cause it too.

    Have you retrieved trouble codes from the A/C around the time it cycles off? All it takes is to hold down AUTO and RECIRC together while turning the car ON. Two-digit codes will show up on the A/C control display.

    If you have a laptop and Techstream, you can flat-out read the refrigerant pressure from the sensor, right there off the screen of your laptop without your hands getting dirty. People without Techstream would have to open the hood and attach a gauge set, like in the dark ages.

    -Chap
     
    #3 ChapmanF, Aug 1, 2018
  4. ASRDogman

    ASRDogman Senior Member

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    "Assuming" it was working, as stated, when they filled it. It wasn't likely overfilled.
    And since it need to be filled, it's more than likely low on freon.
    And since it tries to cool after "x" amount of cycling, it seems it builds up some pressure to try to cool.
    But then it could also be a number of other things including electrical that could be causing that.

    It's easy to look for a hose leaking or connection that may show signs of oil leaking with the freon.
    That is something you can do with only a flashlight.
    The system is probably low on oil also, could damage the compressor.

    If you can see a leak, then you need to take it to someone with gauges or techstream to see the pressures and/or
    any codes. And also a leak detector to find the leak.
     
    #4 ASRDogman, Aug 1, 2018
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