AC fan speed/Driver side blowing only?

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by Zipy, Sep 26, 2018.

  1. Zipy

    Zipy Junior Member

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    Ok, been meaning to post this for some time now. 1. When its HOT out and I want the a.c. blower to start IMMEDIATELY, it doesn't. 2. Fan has a mind of its own, (computer?), and doesn't matter if its on ECO, Auto, or auto off. 3. Also, fan doesn't always blow on passenger side. 4. When Auto is selected it sometimes opens recirculation and blows warm moist air on me. I'm sure this is all our omniscient computer making decisions for us. Don't get me wrong the a.c. blows COLD, but is there some type of alternate programming the dealer can program (or me) ? Sorry for the rant, but it's been a long time coming. I have questioned the service department and they say "Duh, its supposed to do that."
     
  2. The Professor

    The Professor Senior Member

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    1) The speed that the fan speeds up can be adjusted. I did that with the Carista app but there may be other ways. The fan always started within a few seconds on Auto even before I made the adjustment.

    2) On Auto, the computer controls it. You can manually override that simply by adjusting the fan speed manually. If you do that, it should remain at that speed until your adjust it again or put it back on Auto or Defrost. If it's not behaving like that I'd suspecta fault.

    3) That's Driver Priority. There's a button to turn that on or off down near the rest of the air con controls (like Recirculate), it looks like a two people sitting in the seats and one has an X through them. If you only open the driver's door when entering the vehicle, then the car will assume only the driver is present and direct air flow to them. If it gets it wrong, press that button. If you open any other door then all passengers get air flow. Of course this assumes you have the relevent vent open, and in a nice that sends air out the main vent (i.e not feet only or defrost).

    4) It has to occasionally change between recirculation and outside air to remove moisture from the system. Like all car air con, if it didn't go that then toy would get tons of mould and mildew growing, and it would smell like a swamp. Auto will prioritise recirculation, as that is the fastest and most energy efficient way to heat or cool the car, with the exception of a few seconds at the start if the car is super hot. You can change this with Carista again. I believe the dealership can also change the same settings (they're listed near the end of the manual), but Carista was more convenient for me.

    Happy to help more if you need it.
     
  3. sclevine

    sclevine Member

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    The auto AC system isn't going to be perfect all the time, especially when you have a multitude of possible conditions from very sunny to very humid. When I'm not happy with the temperature of the air blowing or the speed of the fan, I just tap the degrees up or down by 2 or 3, and I find the auto system is very responsive.

    And yes I sometimes have to press that button on the dash to blow air through all vents when I am by myself.

    And yes it is annoying when there is a few seconds delay in the fan starting up when I start the car and it is very hot, but I also think the car is great at fairly quickly blowing out cold air.

    My main gripe is that the windows fog up pretty easily in wet and rainy conditions and I find I need to turn the front defroster on and raise the temp several degrees for the fogged windows to clear up. Auto mode does not seem helpful at all when the windows fog up.
     
  4. sam spade 2

    sam spade 2 Senior Member

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    What they told you is the truth.

    And you stated the reason why it is designed that way.

    IF....the fan came on immediately, the initial blast of air could VERY hot and VERY damp.
    So they delay it for maybe 30 seconds to allow the compressor to get the evaporator cool instead of hot before the air flows.

    The passenger side problem you noted is un-related.
    From your description, I doubt that is normal.
     
  5. The Professor

    The Professor Senior Member

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    Sounds to me like the very normal "Driver Priority" function (see my answers above).
     
  6. Zipy

    Zipy Junior Member

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    Thanks guys!
     
  7. Starship16

    Starship16 Senior Member

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    I never use that "auto". :ROFLMAO:

    I just do the settings myself. Like I did in every other car.

    Start the car.
    Push the AC button ON.
    Set the fan speed where you want it.
    Set the Temp where you want it.
    Set the vent selector where you want it.
    Push the "recirc" button ON (or leave off.)

    Takes me 5 seconds.

    I get immediate cold air.

    Go to McDonald's and get an egg McMuffin & coffee. :LOL:

    No problemo. :)

     
    #7 Starship16, Sep 26, 2018
    Last edited: Sep 27, 2018
  8. alanclarkeau

    alanclarkeau Senior Member

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    Have you any passengers at the time?

    There was a thread a while back where someone asked about the delay. My home A/Cs do that too, longer if it's on HEAT mode.

    One of the handbooks say basically "you wouldn't be happy if it blasts freezing air when you've asked for HOT - so it pre-warms the system and, when it's warmed it up, then blows HOT air as requested". I suspect TOYOTA has the same idea, starting with high compressor speed to pre-chill the A/C then turn the fan as required when it can actually blow cold.

    Also
    The Owners Manual (Australian) says:
    upload_2018-9-27_14-33-56.png
     
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