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Heater blowing cold

Discussion in 'Gen 3 Prius Technical Discussion' started by timnthomas85, Feb 24, 2022.

  1. timnthomas85

    timnthomas85 Junior Member

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    Hi when i start my 2013 Prius in the morning the heater blows cold. I have to keep turning it off and back on (sometimes restart the car) to get heat to work. Sometimes takes over ten minutes. But, when I do get it to work, just before it starts blowing hot I hear a rushing-pouring water sound. How do I find out if this problem is the water pump, thermostat, or heating core? Been happening for a couple months. Once I decided to just start driving without waiting for heater to start working. It was a VERY cold morning (below freezing). After a bit of driving the engine temperature warning light came on so i pulled over and shut off the car. As soon as I restarted it i heard the water rushing noise and the heater blew hot and the car was fine.
     
  2. ForestBeekeeper

    ForestBeekeeper Active Member

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    I have found that whenever it is below zero, the first 3 miles of driving our Priuii refuse to put out any heat. I turn on the defrosts [both front and back] during those first 3 miles of driving. By the time that I reach about 6 miles it will definitely put out lots of heat.

    You mentioned below freezing. I have not had any problems in warm weather like that. Just when it is in the negative temps.

    We drive two Priuii, both of them behave in this manner.
     
  3. ASRDogman

    ASRDogman Senior Member

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    I don't think there is a heater valve, maybe someone can answer that.
    Perhaps the thermostat is defective and not opening as it should.
    But, in FREEZING weather, you will NOT have instant heat. The engine must warm up
    to heat the coolant to provide heat. Some people block off most of the radiator with cardboard
    to help speed up the heating process.

     
  4. timnthomas85

    timnthomas85 Junior Member

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    Edit:

    I know that on a very cold morning the heater will not immediately blow hot. If i just sit there with the heater blowing on me it will never get hot. I have to shut it off then back on or restart the car. (Hear water noise) Then it is immediately HOT.
     
  5. ForestBeekeeper

    ForestBeekeeper Active Member

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    Hmm, that is interesting. Off and restart and the heat is immediate. I must try that myself.

    Thank you.

    I had pretty much assumed that a -15F car was the norm for the first few miles.
     
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  6. AzusaPrius

    AzusaPrius Senior Member

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    This is not what happens, you can not have instant heat by turning the car off and back on.

    Make sure ECO is off to get better heat.

    Do not use front defrost that will only bring in cold outside air, that is only used after you have the cabin heated up if needed.

    From cold start it will take about 10 minutes for the engine to get to 104F.

    After that it will cycle on and off to keep that temp, unless you turn the fan up.

    It can get to134F with fan all the way up.
    The temp is set to HI

    The swooshing water sound is from the heater core, have you used any head gasket sealer?

    Keep an eye on your coolant level
    Since you saw overheat warning.

    I am in high desert with below freezing temps so I am fully aware of the system.
     
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  7. timnthomas85

    timnthomas85 Junior Member

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    I've never used sealer. I know this car really well, which is how i know there's a problem. It used to be even on the coldest day I start the car, turn the heat on and imideiatley I can feel it slowly start to get warm. Now, it just blows freezing cold till I start turning it off and on and hear the water noise.
     
  8. rjparker

    rjparker Tu Humilde Sirviente

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    In my 2012 there is an electric auxiliary heater fused at 50 amps that should help until the engine warms up. In eco mode that electric heat is disabled. My understanding is the inverter can also disable the heater if the 12v dc load is excessive or the inverter temperature is high.

    It is conceivable that a weak or old 12v battery could be demanding a very high, maybe 70-80 amp, initial charge from the inverter. Which would be enough to disable the 50 amp electric heater.

    The fastest way to warm up the engine is to drive it. In 30f weather today, my 2012 was producing heat in less than 4 minutes while traveling ~ one mile. The engine was about 110f. Within 7 minutes it was producing very hot "turn it down" heat and the engine was 145f. No rushing water sounds ever.

    If you are hearing water sounds you have low coolant and air in the system. This would be consistent with the high engine temperatures you experienced. Verify the water pump and coolant levels. This is serious and could take out your engine.

    B0376B2A-163F-40E0-868B-590246B78E20.jpeg

    A4902F17-52E1-43BC-A175-636C9415687E.jpeg
     
    #8 rjparker, Feb 25, 2022
    Last edited: Feb 25, 2022
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  9. ChapmanF

    ChapmanF Senior Member

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    My experience with the electric supplemental heat is that you pretty much can't tell by feel whether it is on or not.

    It gives no more than about 700 watts (that is 50 amps at 14 volts), which is a fraction of the 5300 watts or so worth of heat that you get out of the coolant once the engine is warm.

    Putting my hand over a vent blowing subfreezing chilly-morning air, I really can't feel the difference between whether that cold blowing air did or didn't pass through the 700 watt heat element.

    Even though I can't feel the difference, I can definitely see it if the windshield is frosted and I use the front defrost. It will defrost noticeably faster with the electric heat on.

    The ECO mode locks out the electric heater. I am normally in ECO mode, so I have to remember to turn that off if I've got a frosty windshield to clear.
     
  10. ForestBeekeeper

    ForestBeekeeper Active Member

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    Today it is not too cold somewhere between 15F and 18F. So I tried your tip.

    I restarted the car three times. it had no effect. None.
     
  11. timnthomas85

    timnthomas85 Junior Member

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    Dang!
     
  12. ForestBeekeeper

    ForestBeekeeper Active Member

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    I am willing to try any tips or tricks to better operate the Prius. I would like to know some way to get the heat going a bit faster, just in case for the days when it does get cold. We normally see temps around -20F in my township.
     
  13. ASRDogman

    ASRDogman Senior Member

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    Well, as I stated on post #3: "
    Some people block off most of the radiator with cardboard
    to help speed up the heating process."
    Kinda sounds like a sticking thermostat, or maybe you have air in the system.
    And have the water pump checked. The empeller may be swelling and not moving
    the coolant while it's cold. Then after the engine is off, the coolant heats up quicker, then
    the engine runs, the empeller starts to rotate and you get a rush of water.

    You may have to take in to someone who knows how to work on a Prius and have them
    check it out. Sooner rather than later. Because you could be overheating the engine and
    causing damage...
     
  14. Bobbi81

    Bobbi81 New Member

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    I have exact same problem. Just let me know if you figured it out please. Thanks buddy
     
  15. Brian1954

    Brian1954 Senior Member

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    First, look at your coolant to make sure it is at the proper level. What did you find?

    Does the high temperature light come on?

    You could have an engine water pump that is going bad.
     
    #15 Brian1954, Jan 18, 2024
    Last edited: Jan 18, 2024
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  16. ChapmanF

    ChapmanF Senior Member

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    The rushing/gurgling noise isn't good. When the system is full of liquid as it should be, it doesn't make rushing/gurgling noises.

    +1 on checking the function of the water pump also. A scan tool showing the water pump actual RPM might be of interest, during this initial warmup and after stopping and restarting the car.
     
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  17. Bobbi81

    Bobbi81 New Member

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    I founded my head gasket was blown and replaced a few days ago. Now I have another issue: when I put the fan speed on high, I t get warm and after a few minutes cold. I should turn the climate control off then back on with lower fan speed to get heat.
     
  18. Brian1954

    Brian1954 Senior Member

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    Did you replace the engine water pump when you replaced the head gasket?

    Did you ever put stop leak into the engine cooling system.
     
    #18 Brian1954, Mar 13, 2024
    Last edited: Mar 13, 2024
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  19. Bobbi81

    Bobbi81 New Member

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    No, Should I do that? If yes, can I replace the rotor only?
     
  20. Bobbi81

    Bobbi81 New Member

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    When I bought this car a few months ago, the seller did add sealing to it, and I didn't know. I did a 3-time flush and replaced the heater core, head gasket, hoses, reservoir, cap and the head gasket. As my mechanic said, it seems there is no sealing solution remains in the system.