Fan only mode for climate system

Discussion in 'Prime Technical Discussion' started by upnorth, May 16, 2019.

  1. upnorth

    upnorth Member

    Jan 22, 2017
    NW Wisconsin
    2017 Prius Prime
    Plug-in Advanced
    On days with moderate temperatures I have been trying to run the cabin climate system manually with only the fan running to bring outside air into the cabin. If there is an easy way to do this I have not found it in the manual. I have gotten it to work this way some times by the following steps: Turn off the climate system, set the fan speed manually, then off the automatic, air conditioner or anything else that starts along with the fan and then adjust the temperature setting as necessary (if possible) to shut off the heat pump system as indicated in the display by it drawing no power. Depending on ambient temperatures I don't think it is always possible to keep the heat pump from starting.

    It seems to me that it would be nice to be able to run just the fan at a set speed to boost flow of ambient air through car without for heating or cooling. For one thing it gets more EV range and around here there are many days when a little extra air flow is all that is needed. Yes, I could also open a window, that works in town but also adds traffic noise and on the highway open windows are not a benefit to mileage either.

    One more thing. Even with system set to not start the heat pump the EV mileage estimate continues to be calculated as if the heat pump is running, I suppose because it will in fact run if the system thinks it needs to.
    So, have I missed an obvious way to just manually run the fan? If not would this be a useful function to have? I realize I can just set the temperature and not worry about it, called subzero mode around here, but what fun would that be on a nice spring day?
  2. thuwaragan

    thuwaragan Junior Member

    Jan 7, 2015
    Boston, MA
    2012 Prius
    I usually just set the temperature to something low (like 60) and turn off the A/C and manually set the air speed to 1 or 2 fan speed. That has the effect of just pulling in ambient air.
    Prius from Dad and Mendel Leisk like this.
  3. mr88cet

    mr88cet Senior Member

    Sep 9, 2008
    Austin, TX
    2017 Prius Prime
    Prime Advanced
    Indeed. That’s what I do as well, but more specifically, I set it to just below 60, called “LO.”

    That is, until the outdoor temperature goes above 81 or so, then the AC goes on with a temperature setting of 78ish.

    On the cold end (not common here in Austin TX), I usually turn it off completely (i.e., temperature set to LO and the fan off) between 63ish and 50ish outdoor temperature. Below that I usually turn the heater on, set to 65ish, fan on the lowest setting.

    Below 40ish, I usually just wimp out and set it for 72ish and run the fan for real, at least initially. If it’s not much colder than 40 though, I’ll run it that way only for a short time, then turn it all off, keeping the steering-wheel heater on.

    I rarely find that I need to run the seat heater more than a few minutes, unless its waaaaay cold.
    #3 mr88cet, May 16, 2019
    Last edited: May 16, 2019
  4. lextoy

    lextoy Active Member

    Apr 22, 2010
    2018 Prius Prime
    Prime Premium
    i found the AC does not come on unless i turn it on, or hit AUTO(defrost does it too but i rarely use that). if i just turn on the fan to one or two bars , everything is fine.
    i typically leave the temp set to LO and the recirc set to Fresh air. i notice that at speed, even if i have the fan OFF i can feel some fresh air pushing thru the vents if the settings were for full front vents and fresh air when i last turned off the fans. sometimes that is enough.
    also there is a setting in the menus somewhere that you can disable the AC ON WITH AUTO button.
    i like it better that way, now when i hit AUTO it just turns on the fan, but not the AC. with the AC disabled i can just hit the auto button and the fan will do what it needs to to try to get to the temp it is set for, usually fans come on strong since i have temp always set at LO. now that it is warmer, they will never get inside cabin temp down to a point that the fan would taper down its speed. but if i click the temp up a bit i can get the speed to reduce. i could just leave it at 70 i guess...
    i will often vent the car when i first get in by opening a few windows. this is by far the fastest way to bring cabin temp down, even if its 90 degrees out, 90 is better than the 130 that is inside the car!! once temp inside is equalized to outside, i close up and decide how much fan and maybe AC i need.
    high TSER window tint is also helpful to keep temps down. all windows and rear hatch, and front windshield...
    #4 lextoy, May 17, 2019
    Last edited: May 17, 2019
  5. Mendel Leisk

    Mendel Leisk Senior Member

    Oct 17, 2010
    Greater Vancouver, British Columbia, Canada
    2010 Prius
    That is good!

    I really wish too, Toyota would consider adding an "On" button, or at least some published combo of existing buttons you could push, to achieve:

    Turning the system back on, as it was.