'02 no heat but running hotter than normal

Discussion in 'Generation 1 Prius Discussion' started by Tryyn, Nov 28, 2021.

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  1. Tryyn

    Tryyn Junior Member

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    We took our 2002 out today to keep the 12V charged, and we discovered we have no heated air coming from the vents. The climate system blows ambient-temp air, so the blower works fine. Checked the coolant level in the reserve tank, and it was low, so we added some more coolant to the tank. Monitoring the coolant temp afterward with a Bluetooth OBD-II scanner, it was around 200-230 degrees, much higher than normal. Would a stuck thermostat result in no heat? That's what we are suspecting. Did not check the climate system actuators or the heater hoses.
     
    #1 Tryyn, Nov 28, 2021
  2. ChapmanF

    ChapmanF Senior Member

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    The thermostat isn't in the heater loop; it only controls when the heat can be shed from the radiator at the front of the car. In general, a stuck thermostat and 200+ degree coolant should be giving you plenty of inside heat.

    It sounds more like your heater core might be plugged, or the air mix door actuator might be stuck.

    I might investigate the actuator first. They are known to get dodgy with age. The heater core really should not get plugged, if the coolant has been changed on schedule and no leak-sealer types of goop have been poured in.
     
    #2 ChapmanF, Nov 28, 2021
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  3. Tryyn

    Tryyn Junior Member

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    OK, I'll run actuator check mode later and investigate what's going on with the air mix door. I don't hear the servo thrashing back and forth as you would normally expect from a failed position sensor, and that doesn't explain the overheating.
     
    #3 Tryyn, Nov 28, 2021
  4. sam spade 2

    sam spade 2 Senior Member

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    You should check the coolant level in the actual radiator.
    You may have lost more coolant than you think........and need to figure out why.
     
    #4 sam spade 2, Nov 28, 2021
  5. Rmay635703

    Rmay635703 Senior Member

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    Or blown a head gasket
     
    #5 Rmay635703, Nov 28, 2021
  6. sam spade 2

    sam spade 2 Senior Member

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    Yes that is one of the possible reasons why.
    There are others.
     
    #6 sam spade 2, Nov 29, 2021
  7. Tryyn

    Tryyn Junior Member

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    Figured out we were just extremely low on coolant. Added coolant up to the base of the filler neck on the radiator, topped up the reserve tank, and now we have heat! Not overheating anymore, either!
     
    #7 Tryyn, Nov 29, 2021
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  8. ChapmanF

    ChapmanF Senior Member

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    I have heard that coolant helps with that. :)
     
    #8 ChapmanF, Nov 29, 2021
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  9. Tryyn

    Tryyn Junior Member

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    Now we need to figure out how all that coolant leaked out in the first place. Will check tomorrow morning for a puddle under the car. Leaking coolant not only reduces your Prius performance, but it also increases its environmental impact...
     
    #9 Tryyn, Nov 29, 2021
  10. sam spade 2

    sam spade 2 Senior Member

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    Deleted by author.
     
    #10 sam spade 2, Nov 30, 2021
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