AC Problems in Phoenix

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by calvinthedasher, Jul 21, 2025 at 3:38 PM.

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  1. calvinthedasher

    calvinthedasher New Member

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    Location:
    Phoenix, AZ
    Vehicle:
    2009 Prius
    Model:
    ----USA----
    Hello All,

    I’m a dasher in the Phoenix area and my dear Prius can’t stay cool. As long as the temperature is 106 degrees and below it’s fine. But once above that point, all I get is hot air.

    Here’s what I’ve done so far in order:
    Swapped out blower motor (original one died)
    Had a local shop recharge the freon with stop leak
    Changed out all fuses and relays related to AC for brand new ones
    Replaced inverter coolant water pump


    My buddy that works on it from time to time still thinks it may below on refrigerant but when the AC works , it’s ice cold. Once it gets to the stopping point temperature wise, I have to turn the car off for a few minutes and pray that the ac works when I turn it back on.

    Any ideas of what could be going on? Please help.

    Thank you in advance
     
    #1 calvinthedasher, Jul 21, 2025 at 3:38 PM
  2. Tombukt2

    Tombukt2 Senior Member

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    Location:
    Durham NC
    Vehicle:
    2009 Prius
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    Base
    When you say stop you stop you mean not air is coming out vents or no blower at all . Wen this is happening is the silver hose marked L cold and compressor whining???
     
    #2 Tombukt2, Jul 22, 2025 at 7:27 AM
  3. calvinthedasher

    calvinthedasher New Member

    Joined:
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    Location:
    Phoenix, AZ
    Vehicle:
    2009 Prius
    Model:
    ----USA----
    Thanks for responding. when I say it stops, the air still blows but it just suddenly gets hot. i don’t hear any whining at all. I’ll check the hose next time it happens and see if it’s cold.
     
    #3 calvinthedasher, Jul 22, 2025 at 5:10 PM
  4. Hayslayer

    Hayslayer Member

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    Vehicle:
    2009 Prius
    Model:
    Touring
    It could be (and is very likely) something as simple as the inverter coolant loop getting too warm at those elevated ambient temperatures. When the inverter cooling loop gets too warm, one of the first things the Gen 2 does is stop the AC to remove electrical load from the inverter in an attempt to get coolant temperature to lower, but gives no codes. (The AC compressor is electric and is supplied power by the inverter) Try to find a way to monitor that coolant temp and see what it's doing real time. Make absolute certain the radiator isn't fouled. The engine coolant loop and Inverter coolant loop share the radiator, but are completely separate systems. If the radiator is fouled, it can be preventing adequate airflow/cooling at those high air temperatures.

    If that's all good, maybe you can experiment and find a way to provide additional cooling to the IC loop? Install a small aux fan/radiator/heat exchanger in the flow path?

    Many people have spent thousands of $$ troubleshooting the AC system intermittent operation when the actual "problem" was in the inverter cooling loop.
     
    #4 Hayslayer, Jul 22, 2025 at 11:01 PM
    Last edited: Jul 22, 2025 at 11:10 PM
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