Gen 2 No heat. Flush heater core?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by LDT08, Jan 20, 2020.

  1. LDT08

    LDT08 Junior Member

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    I have a 2008 gen 2. with no heat. No codes displayed. Engine temperature is normal. Bled the coolant using the bleeding valve. Actuator is moving. After running the engine, the input hose (on the right, facing the car) is warm, the hose on the left is cool. I am open to suggestions. I really do not want to replace the heater core.
    Thank you in advance.
     
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  2. LDT08

    LDT08 Junior Member

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    I flushed the heater core. Elevated the front of the car let it warm and opened the vent on the right side of the radiator to let air out. Still no heat.
     
  3. valde3

    valde3 Senior Member

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    No heat even on max heat setting? When engine is running? Did you check the hose temperatures when engine was running or right after that? Did the heater core flow freely when you tried to flush it? How did you flush it?

    How did you bleed the coolant thermos? Perhaps there could still be air in there?

    Perhaps it's blocked in some other place. Bad coolant control valve? Blocked heater core water pump?
     
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  4. edthefox5

    edthefox5 Senior Member

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    Like Valde said you have to bleed the CHRS thermos bottle by cycling the thermos ump. Pull the CHRS relay out and jump out the relay legs with a paper clip to turn on tat pump and with that bleed valve open you referred to leave it open with pump running till it has no more air in it.
    You elevate the front of the car then open the rad cap.

    Never seen a heater core clogged before. Its always an air lock in the ice coolant circuit. Very hard to bleed. if the chrs pump cycling dont get it then may be 3 way valve.

    How are you monitoring engine temperature?
     
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  5. LDT08

    LDT08 Junior Member

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    Thanks for the replies.
    Heat was full on and car was running. Flushed at the core input out put. I bled using the cock on the upper right side of the radiator. I monitor the temperature with torque, runs about 190.
    Is there a relay for the coolant control valve?
    I will try the paperclip bridge.
    It seems odd one hose on the heater core is warm and one is not.

    No codes or lights
     
  6. Tim Jones

    Tim Jones Active Member

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    What happened on this?
     
  7. SFO

    SFO Senior Member

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    Tried the jumper trick once, and it didn't want to work, and it could've been a problem with the jumper or the jumpee o_O

    Before the above failed attempt there was a preexisting plan to 'ready' and then turn off the vehicle multiple times, each time pausing for the pump to fill the thermos once the engine is off, and again to cycle the warm thermos liquid once the engine starts (y)

    This made bleeding easy peasy, especially when you already know how much you've drained out before hand :whistle:
     
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  8. LDT08

    LDT08 Junior Member

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    Still working on it.
     
  9. LDT08

    LDT08 Junior Member

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    What failed attempt are you writing about?
     
  10. SFO

    SFO Senior Member

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    Was a personal attempt at jumping Pins 3 and 5 to activate the CHRS pump, which was solved by power cycling the vehicle.
     
  11. LDT08

    LDT08 Junior Member

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    I have not tried that yet.
     
  12. Tim Jones

    Tim Jones Active Member

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  13. zach tarbill

    zach tarbill New Member

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    Having the exact same issues in a 2008 as well... see my threat "no heat...whats next?" Coolant control valve, heater pump behind inverter, and radiator replaced so far with no success....
     
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  14. LDT08

    LDT08 Junior Member

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    I am going to test power at the control valve. I will keep you updated.
     
  15. LDT08

    LDT08 Junior Member

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    The heat works. I replaced the heater (auxiliary) pump. Yes, this has been quite a journey. I started by flushing the heater core, replaced the control valve, replaced the thermostat, and replaced the sensor on the thermos tank. Replacing the heater pump solved the problem.

    The old heater pump motor was working, but not pumping. I decided to take the old unit apart and found a mass blocking the impeller. The mass appears to be a piece of foam. I have not tested the mass to see if it is a collection of particles or a piece that broke loose. I due to consistency, I suspect the later. However, I cannot be sure.

    The downside to all of this is, since I cannot identify origin of the mass, it is possible a blockage may be in different locations throughout the system, thus, my solution may not be relevant in all cases.
    The upside is I have a working heater pump for sale. Yes, I tested it.

    During research for this process I have found many misleading (incorrect) comments and diagrams. Please verify information before giving advice. We are all in this together.

    Hope this was helpful.

    Please read through threats to avoid repeat information.

    This image is popular, but it is incorrect.
    in-out-heater-core.JPG

    Blockage
    heater-pump-1.jpg
     
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  16. edthefox5

    edthefox5 Senior Member

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    Nice post nice job.

    I have seen that pump before and thought god I hope I never have to replace that. Its the one mounted on the firewall right?

    I bought my 07 brand new and don't think I have ever turned on the heat not once.I bet that system is pretty gunked up. I have flushed the engine coolant once (that sucked) and dumped the engine coolant out of the rad multiple times.
     
  17. LDT08

    LDT08 Junior Member

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    Thank you
    Yes the pump is back there. The main power plug has to come off. Then it is matter of knowing the order to remove hoses bolts and plugs. The pump has to be removed to get to the pump power plug.
    In your dealing with the coolant system did you detect the source of debris like this? I hope it is not coming from inside the thermos.
     
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