ac delayed start

Discussion in 'Gen 3 Prius Main Forum' started by abubin, Dec 26, 2020.

  1. abubin

    abubin Member

    Joined:
    Dec 7, 2019
    111
    56
    0
    Location:
    Malaysia
    Vehicle:
    2012 Prius
    Model:
    N/A
    My friend's Gen3 Prius which he bought used has been having this issue with the AC. Apparently when he starts the car, the ac will be stuck in auto mode and nothing in the ac will be running including the blower and compressor. He have to wait around 45s then only ac is working as normal.

    This is rather strange. Toyota dealership could not find the problem and there are no engine codes. Any idea where to start checking?
     
  2. bettergolf

    bettergolf Active Member

    Joined:
    Jan 8, 2019
    252
    232
    0
    Location:
    Sanford NC
    Vehicle:
    2015 Prius
    Model:
    Two
    Mine does that delayed start. It doesn't run evidently until it's ready to put out cooled air. Sometimes I'd like it to go ahead and blow just to move some of the hot air in the car. One of the very few things I don't like about my Prius.
     
  3. Johnny Cakes

    Johnny Cakes Senior Member

    Joined:
    Dec 30, 2016
    769
    597
    2
    Location:
    Virginia, USA
    Vehicle:
    2015 Prius
    Model:
    Five
    That makes sense for heat, but the OP says the compressor doesn't run during the delay period.
     
  4. Johnny Cakes

    Johnny Cakes Senior Member

    Joined:
    Dec 30, 2016
    769
    597
    2
    Location:
    Virginia, USA
    Vehicle:
    2015 Prius
    Model:
    Five
    45s = 45 seconds? Some reports are a minute or two.

    This has been reported across the Toyota product line for years.

    Here's a technical bullitin for Highlanders
    https://static.nhtsa.gov/odi/tsbs/2016/SB-10087945-5448.pdf

    If not an defect, internet speculation for why Toyota designed it this way:

    (1) fuel economy reasons. -- keeping the compressor off keeps engine load lower during warm up when the engine is running very rich. After a min or 2 (or drive a mile) the engine is warm enough it comes out of the warm up cycle and the compressor comes on;

    (2) delay on the compressor starting until the engine warms up to a pre-determined temp for the purpose of lowering cold engine emissions.

    (3) reduce the amount of energy to start the engine -- load on traction battery at ICE crank;

    Of course, on the Internet you get what you pay. Internet opinions are like butts -- everybody's got one and everyone thinks everyone else's stinks.
     
  5. BZzap!

    BZzap! Senior Member

    Joined:
    Jun 13, 2012
    1,575
    851
    0
    Vehicle:
    2012 Prius
    Model:
    Two
    There is no instant gratification with the Prius A/C. I suspect that the system is designed that way in order to pre chill the evaporator to prevent hot air blasting in the occupant’s face. Many times I’ve had conversation with my HVAC to ask it to “HURRY UP”! Other than this slight misgiving the A/C in my Prius is one of the best systems I’ve had. The performance on a 100 degree + day is outstanding.
     
  6. AzWxGuy

    AzWxGuy Weather Guy

    Joined:
    May 22, 2011
    794
    387
    0
    Location:
    Tucson, AZ
    Vehicle:
    2021 Prius
    Model:
    Limited
    I can't recall mine ever doing that. It got going, cooling things off, right away on plenty of 100+ days. I know the heat would always wait until the ICE coolant was sufficiently hot before the blower would get going. The fuzzy logic of the HVAC ECU. Is the vehicle mode in ECO vs. Normal? That will throw in some delays, maybe in both the cooling and heating cycles. I rarely to never used ECO. so can't accurately report. Lastly, always check the 12 V battery health when electrical shenanigans begin.
     
  7. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    12,809
    9,252
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    The compressor is variable speed and can be fairly quiet in the lower reaches, so a report that the compressor "isn't running" at all might be worth taking with a grain of salt, unless the person was actually watching a scan tool monitoring the compressor RPM at the time. It might just be starting low and ramping up. I think that's what mine does.
     
  8. ASRDogman

    ASRDogman Senior Member

    Joined:
    May 29, 2018
    3,475
    2,122
    0
    Location:
    Florida
    Vehicle:
    2010 Prius
    Model:
    Two
    According to the service bulletin, there is and "updated A/C compressor and A/C amplifier".
    So apparently, this is not normal.



     
  9. Johnny Cakes

    Johnny Cakes Senior Member

    Joined:
    Dec 30, 2016
    769
    597
    2
    Location:
    Virginia, USA
    Vehicle:
    2015 Prius
    Model:
    Five
    Now that you mention it, compressor RPM is a setting that can be toggled in the the OBDII settings:
    A/C compressor noise reduction: Enabled / Disabled
     
  10. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    12,809
    9,252
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Beyond that, it isn't anything like constant. The car is continually adjusting it up or down according to a control algorithm, taking into account inside and outside temperatures, temperature setting, solar sensor, refrigerant pressure, yada yada.
     
  11. Johnny Cakes

    Johnny Cakes Senior Member

    Joined:
    Dec 30, 2016
    769
    597
    2
    Location:
    Virginia, USA
    Vehicle:
    2015 Prius
    Model:
    Five
    Beyond what?
    I assumed that setting limited max compressor RPM across all variables to reduce noise.
     
  12. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    12,809
    9,252
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Sure, but a setting that makes a slight adjustment to the max RPM limit is probably not going to be the story behind someone thinking their compressor isn't running. That's more likely to be when the compressor is running nowhere near the max RPM limit.
     
  13. BZzap!

    BZzap! Senior Member

    Joined:
    Jun 13, 2012
    1,575
    851
    0
    Vehicle:
    2012 Prius
    Model:
    Two
    With windows rolled up it’s very hard discern the air compressor from inside the car. Standing outside, in the front of the car is a whole different story.
     
  14. ASRDogman

    ASRDogman Senior Member

    Joined:
    May 29, 2018
    3,475
    2,122
    0
    Location:
    Florida
    Vehicle:
    2010 Prius
    Model:
    Two
    If only there were a device you could put up to or in the vent and see if the temperature
    starts getting cooler.... Maybe one day someone will invent something.....
    Until then, put your hand a few inches in front of the vent. If it is getting cold, it's a sure bet the
    compressor is working.
     
    #14 ASRDogman, Dec 26, 2020
    Last edited: Dec 27, 2020
  15. Johnny Cakes

    Johnny Cakes Senior Member

    Joined:
    Dec 30, 2016
    769
    597
    2
    Location:
    Virginia, USA
    Vehicle:
    2015 Prius
    Model:
    Five
    Absolutely -- not saying that at all. Just backing up your assertion that compressor RPM makes a difference as to sound.

     
  16. Paul E. Highway

    Joined:
    Mar 7, 2020
    84
    63
    0
    Location:
    Hawaii
    Vehicle:
    2010 Prius
    Model:
    Four
    My A/C is set to “Auto” at 70-72F and A/C comes on right after I press the start button. It’s usually 75-90F outside when I get in car.
     
  17. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    43,929
    31,488
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    There’s an X-Gauge you can program into ScanGsuge II, for ACWATTS; did that, and saw various values, anywhere between zero and maybe 500.

    If I recall correctly there’s something about delayed start up of cabin ventilation system (with/without AC on) in Owner’s Manual, at least for our 2010.
     
  18. jerrymildred

    jerrymildred Senior Member

    Joined:
    Oct 28, 2016
    9,682
    11,860
    0
    Location:
    Tampa, FL
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    And there you have it. (y) The compressor starts gradually to save energy and wear and tear. Modern house units do the same. The blower waits for the compressor to be ready to provide chilling. All that takes time.

    As for theories about waiting for the engine to warm up, if that was true, my A/C would practically never come on at all since my engine runs so rarely. :D
     
Loading...