1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Best temperature setting for summer to avoid constant ICE turning on?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by h1ph0panonymous, Apr 14, 2024.

  1. h1ph0panonymous

    h1ph0panonymous Junior Member

    Joined:
    Oct 9, 2023
    67
    14
    0
    Location:
    Minnesota
    Vehicle:
    2014 Prius
    Model:
    Four
    Noticed my ICE turns on when it should be in EV mode after the 30 second warm up from starting the car during my pass through at my work parking lot even when temperature control is off, I had previously set everything to LO and face blow the trip prior to that start up. Everything was turned off yet the ICE kicked on when I started driving through the parking lot when it normally should’ve been in EV mode. What gives, does the AC need to be disabled before turning the fan to OFF?

    Doesn’t the AC run off of the big battery pack and not the ICE drivetrain? My batteries were at 80-90 percent per usual after a 30 second start up and regen so it wasn’t a battery issue during that parking lot pass through.

    2014 Prius 4 50k miles.

    Did not come with a manual when bought so don’t know if I’m missing something pertaining to the least ICE engagement setting for summer driving now that it’s final hot out. For the record I drive with windows open I just want a setting ready for when I drive my daughter around. I heard driving with the settings on heat mode helps relieve strain on the engine during the summer? Should I just leave it on heat mode then because the EV mode works nice when the fan is on OFF from a heat mode in preset in memory. It’s just funky everything being electronic on it so the jargon is weird.
     
  2. AzusaPrius

    AzusaPrius Senior Member

    Joined:
    May 27, 2020
    1,774
    793
    0
    Location:
    California
    Vehicle:
    2010 Prius
    Model:
    IV
    Using the A/C during summer should not trigger the ICE.

    Using the heater during winter will trigger the ICE.

    You are saying the ICE runs more than it should then it points to your HV battery needing to be replaced soon.

    ECO setting keeps the ICE from running more during winter while using the heat.

    A/C is using only the HV battery.

    Heat setting will trigger ICE more depending on outside temps.
     
  3. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,867
    4,647
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    To stay in ev even with a full hv battery you have to be very light on the “gas” pedal and slowly accelerate to perhaps 20-25 mph. Otherwise the engine will start.

    On top of that the coolant temperature drops fast when the “warm up” period ends. It may go from ambient to 115f in that first warm up and then cools quickly forcing the engine on again. Particularly if the ambient temperature is cool.

    Running heat will cause more engine runtime. AC only uses more hv battery but does not force the engine.

    Th bottom line is a Prius hybrid has a very small ev battery when brand new and might run a mile under ideal conditions like level or down sloping roadway. Using ev on purpose in this car is actually bad for mpg.
     
    #3 rjparker, Apr 14, 2024
    Last edited: Apr 15, 2024
  4. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,631
    15,318
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    The air conditioning uses energy from the traction battery. For that to happen, there has to be energy in the traction battery.

    If your Prius is a plugin model, there are two ways for energy to get into the traction battery: running the engine, or plugging the car in.

    If it is an ordinary, non-plugin Prius, running the engine is the only way.

    The A/C compressor is variable speed. It will drain the traction battery about ten times as fast at its highest speed as it will at its lowest. What speed the compressor runs will depend on how big the difference is between the cabin temperature and the temperature you have set.

    If you are expecting EV mode to last very long in a non-plugin Prius, you're just expecting too much. The non-plugin battery is only big enough for maybe a few blocks of slow driving in EV mode.
     
  5. h1ph0panonymous

    h1ph0panonymous Junior Member

    Joined:
    Oct 9, 2023
    67
    14
    0
    Location:
    Minnesota
    Vehicle:
    2014 Prius
    Model:
    Four

    So the thing is the ICE will turn on if the engine is not 137 degrees or hotter when heat mode is ON.

    When the fan is set to OFF the ICE won’t kick on when cruising through the parking lot no matter the temperature other than the default temperature the car likes to be in (90-115 degrees) but it’s always in the range, I force the ICE on by turning the heat mode on right before going on the main road from the parking lot.

    The ICE was turning on this time when the temperature was preset to LO and A/C ON but the fan was OFF I’m asking why the ICE would turn on if the engine temp was 115 from the warm up when I started feather cruising away, barely touched the gas pedal, while temperature settings were off during this feather cruise?
     
  6. h1ph0panonymous

    h1ph0panonymous Junior Member

    Joined:
    Oct 9, 2023
    67
    14
    0
    Location:
    Minnesota
    Vehicle:
    2014 Prius
    Model:
    Four

    Yeah I was doing the usual feather pedal cruise through the parking lot and the ICE kicked on this time, I had the fan OFF but the (which again wasn’t on because the fan was set to OFF) preset mode was LO and A/C ON with face blow setting.

    That’s the only change I’ve made since winter driving, so I put it back into heat mode and fan mode OFF and normal EV use returned.
     
  7. AzusaPrius

    AzusaPrius Senior Member

    Joined:
    May 27, 2020
    1,774
    793
    0
    Location:
    California
    Vehicle:
    2010 Prius
    Model:
    IV
    Perhaps your feathering of the pedal was just a tad too much?

    What did the HV battery look like was it full or two bars?
     
  8. h1ph0panonymous

    h1ph0panonymous Junior Member

    Joined:
    Oct 9, 2023
    67
    14
    0
    Location:
    Minnesota
    Vehicle:
    2014 Prius
    Model:
    Four
    I was doing my usual feather cruise through the parking lot but this time the ICE kicked in immediately from barely feathering it as per usual 7 days a week in the winter. During the winter I have the fan mode in OFF until I get on the main road because that’s when I need the ICE to kick in anyway. I have a scangauage2 so I know the temps the ICE kicks on for an ACTIVE/ON mode for heat which is at least 137 degrees or hotter. Just weird that ICE is kicking on with fan mode OFF with a preset ready mode of LO and A/C on.
     
  9. h1ph0panonymous

    h1ph0panonymous Junior Member

    Joined:
    Oct 9, 2023
    67
    14
    0
    Location:
    Minnesota
    Vehicle:
    2014 Prius
    Model:
    Four
    I didn’t transition over to the ICE bar on the hud display, idk I’ll try again pretty sure I was looking at the bar as I always do. Just feels like the vents blow air even when fan mode is off and depending on what HI or LO setting you had on prior to turning the fan to OFF will be still feeling hot or cold air coming through the vents, slightly but still can feel the air. So it makes me wonder is the preset mode still engaged?
     
  10. h1ph0panonymous

    h1ph0panonymous Junior Member

    Joined:
    Oct 9, 2023
    67
    14
    0
    Location:
    Minnesota
    Vehicle:
    2014 Prius
    Model:
    Four
    In the winter because it takes longer for the car to warm up to default temp 100 degrees the battery will be actually 90 percent full because it charges while warming up on start up. Now it’s warmer outside it was probably 85 percent full, still haven’t programmed my scan gauge 2 to show x-code gauge of battery percent but since it warmed up fast in warm weather it didn’t get it normal 90 percent warm up charge, anyway 80 percent is enough for EV driving but I guess not with the preset of LO and A/C on while fan mode OFF.
     
  11. AzusaPrius

    AzusaPrius Senior Member

    Joined:
    May 27, 2020
    1,774
    793
    0
    Location:
    California
    Vehicle:
    2010 Prius
    Model:
    IV
    What I am trying to say is, the way you are using the A/C LO and OFF is and will NOT trigger the ICE to come on.

    The ICE will cycle on when battery needs it.
     
  12. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    11,031
    4,483
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    You got a 10 year old battery pack that's lost its capacity so it's going to power up the ICE more frequently as time goes by. Either upgrade to something with more amps: Toyota hybrid battery upgrade pack - NexPower Energy or just restore your lost capacity in your existing pack by doing three increasingly deeper discharges followed by a full charge and balance. Learn more here: FAQ - Hybrid Automotive
     
    h1ph0panonymous likes this.
  13. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,631
    15,318
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Yeah, if you pressed the OFF button on the climate control, the whole system is OFF, not just the fan.

    There are some changes to engine temperature setpoints that you might not expect when the climate system is turned off. You can read about them in the first post in this thread:

    on hunkering, Gen 3 style | PriusChat
     
  14. fuzzy1

    fuzzy1 Senior Member

    Joined:
    Feb 26, 2009
    17,237
    10,129
    90
    Location:
    Western Washington
    Vehicle:
    Other Hybrid
    Model:
    N/A
    If you don't yet have the manuals, then download e-copies from here:

    Toyota Manuals and Warranties | Toyota Owners

    Your vehicle has four items here: the full regular Owner's Manual, the quick reference version, a separate manual for "Entune Premium Audio with Navigation and App Suite", and a "Prius Warranty and Maintenance Guide".
     
    #14 fuzzy1, Apr 14, 2024
    Last edited: Apr 14, 2024
    h1ph0panonymous likes this.
  15. h1ph0panonymous

    h1ph0panonymous Junior Member

    Joined:
    Oct 9, 2023
    67
    14
    0
    Location:
    Minnesota
    Vehicle:
    2014 Prius
    Model:
    Four

    I see, EV seems to be more available when it’s OFF but also when it’s preset to HI heat with A/C disabled.


    Typical?
     
  16. h1ph0panonymous

    h1ph0panonymous Junior Member

    Joined:
    Oct 9, 2023
    67
    14
    0
    Location:
    Minnesota
    Vehicle:
    2014 Prius
    Model:
    Four

    I swear last summer ICE would only kick on if it was nearing 20 percent with A/C On and fan engaged. Idk I’ll try it more but I could probably go a little less than a mile on flat road just on EV mode before it hits 20 percent.
     
  17. fuzzy1

    fuzzy1 Senior Member

    Joined:
    Feb 26, 2009
    17,237
    10,129
    90
    Location:
    Western Washington
    Vehicle:
    Other Hybrid
    Model:
    N/A
    In old cars experiencing overheating problems, setting cabin climate control to put out heat will help cool the engine. But this can be very rough on the human occupants, who are more important than the car, so reserve this for emergency situations.

    Decades ago, when grandpa/ma were visiting on a very hot day and couldn't get up a nearby major hill because of engine overheating, they called for help, mom and dad went down to help. Grandma was moved to our car, and grandpa was told to try turning on the heat full blast and open the windows. He didn't initially understand, but complied. Part way up the hill, with lots of heat flooding the cabin but his car climbing without any more overheating, he suddenly understood why this works.

    Weather soon cooled, and they made it home without further incident.
     
    h1ph0panonymous likes this.
  18. Brian1954

    Brian1954 Active Member

    Joined:
    Jan 31, 2021
    758
    289
    0
    Location:
    South Central PA, USA
    Vehicle:
    2011 Prius
    Model:
    III
    The ICE will turn on to charge the HV battery when it drops to 40%, not 20%.
     
  19. h1ph0panonymous

    h1ph0panonymous Junior Member

    Joined:
    Oct 9, 2023
    67
    14
    0
    Location:
    Minnesota
    Vehicle:
    2014 Prius
    Model:
    Four

    Yeah I don’t have heat mode actively engaged, just preset to heat mode with the fan OFF. I did you a grill cover mod this past winter, still seems like heat preset with fan OFF gives the best EV availability. It’s like something is still engaged if you have it to preset LO and A/C on when you turn the fan OFF in that preset compared to a disabled heat preset.

    Either I’m just learning about this because it will be the first start of a summer in this car for me or something else is going on. Anyway I really don’t need the A/C on during the summer except for some days when it’s advised so I’ll just leave on OFF with the heat preset, seems to be off gassing some residual engine heat through the vents with the fan on OFF so guessing that’s a good sign for the engine. Yes I did also remove my grill cover mod a little too early this year but it’s off. Nothing else sounds like it’s the issue except for leaving the temperature to LO with A/C on before turning the fan to OFF.
     
  20. h1ph0panonymous

    h1ph0panonymous Junior Member

    Joined:
    Oct 9, 2023
    67
    14
    0
    Location:
    Minnesota
    Vehicle:
    2014 Prius
    Model:
    Four

    Meant 20 percent as in 2 bars of battery, I don’t have my scan gauge 2 to show actual percentage yet so just guessing 2 bars is 20 percent? But yeah ICE will kick in when it’s nearing or at 2 bars.