I spent an hour bleeding the radiator and still the cabin air is cold

Discussion in 'Gen 2 Prius Technical Discussion' started by andy song, Jan 27, 2026 at 10:50 PM.

  1. andy song

    andy song Junior Member

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    Location:
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    Vehicle:
    2011 Prius
    Model:
    Four
    My 2008 prius was loosing coolant and we got a new radiator and water pump as it has 320k miles so we figured it was time

    Put the car into maintenance mode and turned the heat all the way up to max in the cabin and started filling it up with coolant

    2 bottles (1 gallon jugs) later the cabin air is still cold

    I would say I waited almost an hour

    I kept pouring in coolant into the radiator cap as the level dropped

    Sometimes it will bubble up and pour out and then it would drop and I would fill it back up

    The thermostat was also replaced BTW

    Any ideas what I am doing wrong?
     
    #1 andy song, Jan 27, 2026 at 10:50 PM
  2. BiomedO1

    BiomedO1 Senior Member

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    Vehicle:
    2021 Prius Prime
    Model:
    LE
    You should probably check your heater water pump and heater control valve (3-way switch valve) and I believe you have a coolant bleed valve on a 2008 Prius. Follow OEM procedures and independently verify that coolant is moving where is suppose to. Just feel the external hose temperatures to verify flow.

     
    #2 BiomedO1, Jan 27, 2026 at 11:09 PM
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