AC door knocking sound plus no condensation ever

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Fredii, Jun 1, 2026 at 3:07 PM.

  1. Fredii

    Fredii Junior Member

    Joined:
    Jan 10, 2022
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    Location:
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    Vehicle:
    2009 Prius
    Model:
    II
    My 2009 Touring never has condensation, anywhere under the car, and no where in the front floorboards. I tried cleaning the condensation tube by forcing water in and out, and the water didnt seem to go anywhere.

    There is also a knocking sound, like a 4" little man inside the passenger dash trying to get out, about half a dozen times and then he stops. it comes and goes, often with the car just turned off.

    AC WORKS fine! It cools and heats appropriatly. Recirc seems to be fine. I have not found a corrrelation between the AC controls and the little man knocking.

    Any help would be appreciated.

    No codes. No engline lights.
     
  2. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
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    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    1. How long do you drive it with ac on?

    2. When you say water forced in the drain goes no where do you mean it acts like the drain tube is blocked?

    3. Have you tried the evaporator foam cleaner with press in tube? It should force foam up the condensation tube drain and will not flow back until the foam liquifies. If blocked I would expect the foam to come back immediately as foam.

    4. Have you removed the cabin air filter and carefully inspected for animal nesting?

    5. When ac is running full blast what is the vent temperature?

    6. With ac running is the underhood sight glass showing bubbles?
     
  3. Fredii

    Fredii Junior Member

    Joined:
    Jan 10, 2022
    15
    2
    0
    Location:
    24153
    Vehicle:
    2009 Prius
    Model:
    II
    1. How long do you drive it with ac on?

    Doesnt seem to matter how long AC is on.

    2. When you say water forced in the drain goes no where do you mean it acts like the drain tube is blocked?

    yes, like its really hard to push any water into it. I really forced some water into it, and it started coming out of some horizontal seems on to the carpet on the passenger side.

    3. Have you tried the evaporator foam cleaner with press in tube? It should force foam up the condensation tube drain and will not flow back until the foam liquifies. If blocked I would expect the foam to come back immediately as foam.

    yes, I tried this. Foam came back quickly.

    4. Have you removed the cabin air filter and carefully inspected for animal nesting?

    yes

    5. When ac is running full blast what is the vent temperature?

    I can check,

    6. With ac running is the underhood sight glass showing bubbles?[/QUOTE]

    What is this?? sight glass??