No heat - what's next?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by zach tarbill, Jan 26, 2020.

  1. zach tarbill

    zach tarbill New Member

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    Picked up an 08 touring last week with no heat, bad windshield, bad 12v, and no red triangle or check engine light but stored P0A80 code. 175k miles.

    1.)Got the 12v replaced and added a ton of coolant to get it all topped off over a gallon. This showed me the radiator had a big leak at the top.

    2.)Replaced the radiator. Did not fully drain the block/trans axle just out of through lower rad hose.

    3.)With the front end up on ramps, bleeder valve on top of radiator open and inverter bleeder valve open I added coolant until coolant came out the bleeder valves with no air bubbes.

    4.) Closed the bleeder valves and with a large funnel in the radiator fill and full of coolant I jumped the relay to run the coolant pump in 5second intervals until I heard consistent liquid movement. This took a little more coolant from my funnel but not much.

    5.) At this point ive gotten just shy of 1.5 gallons in (remember I didn't completely drain the system up front).

    6.) Start the car up in maintenance mode

    7.) Set heat temp to high and clicked defrost button

    8.) After letting the car run like this up on ramps for 15 min I still had no heat and no more coolant pulled in via the funnel and no bubbles coming up.

    9.) Scan tool showed coolant around 190

    10.) Moved heat position to face vents and let run another 30 min. Still no heat.

    11.) Shut it down and let it sit for about 30 min.

    12.) Cracked bleeder valve again with small hose on it. No air just coolant.

    13.) Fired back up still in maintenance mode let run with rad cap on. Coolant up to 190 again. Zero heat. The vent temp was equal to outside temp about 35degrees.

    I noticed that even in defrost mode all face vents still have solid air flow coming out. Switch to feet only and all face vents still have solid airflow but feet air is now blowing.

    Should I be looking at something other than an air in coolant system issue?

    Thank you for your help!!
     
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  2. bisco

    bisco cookie crumbler

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    thermostat?
     
  3. zach tarbill

    zach tarbill New Member

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    Would the operating temp be normal in this case?
     
  4. valde3

    valde3 Senior Member

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    Either heater core is is not flowing coolant through or temperature control door is stuck at cold. You can check for heater core coolant flow by just feeling the hoses to and from heater core they should be heating up with the running engine and be same temperature. For temperature control door you could check if the actuator is moving. If actuator is moving then the the door must be somehow broken.

    If you (with Prius in ready and park, engine not running and blower turned off) turn the heat from max hot to max cold and back, do you hear any noise from actuator?

    OP had checked the coolant temperature with scan tool so it really can't be a bad thermostat.
     
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  5. zach tarbill

    zach tarbill New Member

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    I will try listening for actuator noise this evening. And try to locate the heater core hoses to feel for heat Thank you!
     
  6. zach tarbill

    zach tarbill New Member

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    #6 zach tarbill, Jan 28, 2020
    Last edited by a moderator: Jan 28, 2020
  7. valde3

    valde3 Senior Member

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    Actuator making noise during the test probably means it's ok. Especially if it only makes noise during the test (when you change temperature) and not all the time.

    Coolant loops are kind of hard to follow as there are two separate loops (inverter and engine).

    Inverter: https://attachments.priuschat.com/attachment-files/2019/05/166831_upload_2019-5-11_11-43-41.jpeg
    Engine: https://attachments.priuschat.com/attachment-files/2016/09/113293_Cooling_Loop-CHRS.jpg

    Hoses that are related to inverter cooling loop should not get hot.

    If I got your picture correctly the hose that upper arrow is pointing is the hose from heater core water pump to coolant flow control valve. Is it? If it's and it's not getting hot when engine runs there's blockage somewhere. Most likely option is coolant flow control valve. But it should create a fault code and fault light when failed?

    Noise might be related to the heater storage tank system as well. I'm not familiar with that system as the system is only installed on North American Prius models.
     
  8. ChapmanF

    ChapmanF Senior Member

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    The Gen 2 air mix door actuator should be fairly easy to see once your head is about where the driver's feet go. Then you can check not only that it is making noise, but going to the right positions.
     
  9. zach tarbill

    zach tarbill New Member

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    Correct, in the first photo it is the upper arrow that points to the line that goes to the heater pump behind the inverter. I think I am narrowed down to either the coolant control valve or the heater pump behind the inverter.

    I have read of a few people with some sort of foam debris that clogged the heater pump behind the inverter. The pump still ran, just little to now flow and no codes.

    The coolant control valve seems to almost always have check engine light and code. I have no engine light or code for this. Only a stored code for the hybrid battery P0A80.

    I think next steps this weekend I will go get a used pump and control valve from a local salvage yard and replace both at the same time (only one more drain and bleed cycle this way.) I hate just throwing parts at it, but all the threads I have read through sound like the dealer will do the same especially if they have no codes to go off of.
     
  10. valde3

    valde3 Senior Member

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    It really can't be just a bad heater water pump. A heater water pump is not needed (or used) when engine is running. So just bad heater water pump would cause you to only have heat when engine is running.

    Another place that could be blocked is heater core itself. I have only seen them getting blocked when someone used leak fix in the cooling system though.

    There's one test that you can do. And you can do the test easily when going for changing coolant control valve. You could try to test for for a blockage in the system. You could blow into the line that goes from coolant conrol valve into the heater water pump with radiotor cap off. Air should go through heater water pump, heater core, engine water pump, engine, upper radiator hose and out from missing cap. This would at least tell if there's blockage in heater water pump or heater core. It should be relatively easy to blow air through (much easier than balloon for example).

    If you used that test and found it to be blocked you would disconnect the hose from the engine to heater core and do the test again. If still blocked you could test the heater core and heater core water pump separately to find which one is blocked.
     
    #10 valde3, Jan 29, 2020
    Last edited: Jan 29, 2020
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  11. zach tarbill

    zach tarbill New Member

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    Looking at the attached picture I am trying to understand when/how engine water pump driven coolant gets to the heater core. In the diagram it appears that coolant is always going to the heater core through the hose on the left and comes back out on the right. So when the engine is running, the belt driven water pump is pushing coolant into the heater core. And when the ICE is not running the water pump (for heater) is pulling coolant through the heater core from the engine? This feels off to me?

     
  12. valde3

    valde3 Senior Member

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    Sorry but I just don't understand why that would feel off to you.
     
  13. zach tarbill

    zach tarbill New Member

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    I guess I imagined the heater pump to be pushing through the heater core not pulling
     
  14. valde3

    valde3 Senior Member

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    Electric pumps almost always pull coolant from heater core (or cooler) because then they get colder coolant and stay working longer.
     
  15. ChapmanF

    ChapmanF Senior Member

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    It's a closed loop, right? Nothing that pump is "pulling" that it hasn't already "pushed".
     
  16. Salumi

    Salumi Junior Member

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    change the head gasket
    Or change the engine
    But i change the head gasket every time
     
  17. ChapmanF

    ChapmanF Senior Member

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    Sometimes a change of scenery does help. Then when you're done with the head gasket, you can come back to this problem refreshed and ready to find out what's going on.
     
  18. Salumi

    Salumi Junior Member

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    Once you change the head gasket
    You will not come to this problem
    But still changing engine is easy to quick and problem free fix in and that it
     
  19. LDT08

    LDT08 Junior Member

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    Good Day
    I have a 2008 Prius with no heat. I have looked at the diagram above and I believe it is wrong. When I feel the hoses to the heater core, the right hose is warm and the left hose is cold. (As I am facing the car) I have seen the picture before. I believe the hoses are correct in the attached file.
    . in out heater core.JPG

    View attachment 186119
     
    #19 LDT08, Feb 3, 2020
    Last edited by a moderator: Feb 3, 2020
  20. zach tarbill

    zach tarbill New Member

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    Status update - sorry for the delay as I was waiting for parts...

    1.) I replaced the heater pump behind the inverter under the cowl. The heater pump was full of some type of foam debris blocking the inlet/outlet which I have read about in other posts. See pictures of the good one vs the plugged up one.

    2.) Got it all back together and still no heat.

    3.) I then replaced the coolant control valve, once again no heat.

    This round the upper radiator hose didn't get warm like it wasn't pumping or was blocked.

    So far I have replaced the radiator, the heater pump, and the coolant control valve. I am mildly fed up... ha... Next I am thinking to pull the water pump and thermostat to inspect/replace.

    With all the headgasket comments - would that lead to no heat at all? The oil looks good and ive drain the coolant now 4 times and never see any oil contamination..

    Thoughts before I order waterpump/thermostat?

     
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