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  • 2011 Toyota Prius Not Heating

     Dan updated 6 months, 3 weeks ago 3 Members · 4 Posts
  • Drew

    March 29, 2021 at 11:47 am

    Having heating problems. Heat works after 15 minutes + of driving, but only on driver side. Air volume is low.

    First of all, found a mouse home under the dash. No mouse. All visible wires seem to be in good condition. No check engine light.

    This vehicle does not have a duel zone HVAC.

    Flushed the heater core twice and replaced the thermostat.

    One “flap” obstructed in the picture, but shown with a red arrow is partially opened. The rest were closed.

    My guess is that the air door actuator is compromised. What is a good way to tell this is functioning properly?



  • Mike

    March 29, 2021 at 12:18 pm

    I think we are may be seeing 2 or 3 separate complaints here. Does it seem like it takes too long to get heat initially? You’re comment about “15 minutes of driving” seems to state that.

    •Heat takes too long – Verify coolant temp to the evaporator core. Ensure both hoses are hot and within a couple of degrees of each other. Coolant sealer products have a tendency to plug up heater core passages. While this would affect air temp, it would not affect air volume.

    •Air volume is low – Remove blower fan assembly and ensure motor and housing are free of debris. If possible, attempt to inspect evaporator core and heater core from blower housing. The core(s) may be restricted resulting in a reduced flow.

    •Heat only on the driver’s side – This may be an issue with that centralized flap, or it could be the result of the low air volume. I would suggest addressing/fixing the total low air volume prior to chasing heat only on one side. If the central flap were problematic, only allowing hot air to come from the driver’s side, I’d expect to see an abundance of air volume.

    • Drew

      March 29, 2021 at 12:29 pm

      Yes, it takes too long to get heat.

      -Heat takes too long – Does checking the coolant temp require a scan tool, are you suggesting to the touch on the hose, or infrared thermometer?

      -Air volume is low – This assembly is not fun to get to. Obstruction does seem to be an answer for all issues though.

      -Heat only on the driver’s side – It appears that a single actuator controls all main registers, as seen in my original image. All vents seem to have low air volume.

  • Dan

    April 5, 2021 at 10:33 am

    Hey Drew,

    Do you use the ECO button on the car? In Eco mode the PTC heater grids are turned off to save energy. (poor heat condition).

    Have you located any obstructions in the heater box?

    That main actuator door may be your cause of both conditions. Removing the actuator and marking its sweep and verify the door moves freely is the only way I have ever tested a blend door/actuator concern.

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