Air Con not coming on

Discussion in 'Gen 4 Prius Technical Discussion' started by The Professor, Mar 22, 2022.

  1. The Professor

    The Professor Senior Member

    Joined:
    Apr 5, 2018
    564
    758
    0
    Location:
    UK
    Vehicle:
    2017 Prius
    Model:
    Excel
    Hi all.

    So a few months ago my air con definitely worked. But now it's not. I can't hear the compressor coming on at all. I've double checked the AC button(light) is on, I've turned the climate control temperature right down, and it should definitely be coming on.

    At first I assumed it might just need regassing because the car is about 4.5 years old and nothing has ever been done to the AC, but surely I would still hear the compressor?

    There are no errors displayed, and no OBDII scancode errors (according to Torque).

    I can't hear any clicks, e.g. from a relay, when I toggle the AC on/off. I'm not sure if I could before. But the green AC light does come on when I toggle the AC on.

    Does anyone know where the fuse is located so I can check that?

    Anything else to check before I send it to the dealership?
     
    alanclarkeau likes this.
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    97,739
    44,337
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    have you tried both auto and manual?

    is the fan working?
     
  3. The Professor

    The Professor Senior Member

    Joined:
    Apr 5, 2018
    564
    758
    0
    Location:
    UK
    Vehicle:
    2017 Prius
    Model:
    Excel
    Yeah tried both Auto and a Manual. The fan is blowing air fine, and heating (hot air) is working.
     
  4. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    97,739
    44,337
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    if you can, check the wiring at the compressor. hopefully no vermin or corrosion
     
  5. The Professor

    The Professor Senior Member

    Joined:
    Apr 5, 2018
    564
    758
    0
    Location:
    UK
    Vehicle:
    2017 Prius
    Model:
    Excel
    Well here's where I feel like a total newbie... Any idea where the compressor is when looking at the ICE?

    Is there a fuse for it?
     
    alanclarkeau likes this.
  6. The Professor

    The Professor Senior Member

    Joined:
    Apr 5, 2018
    564
    758
    0
    Location:
    UK
    Vehicle:
    2017 Prius
    Model:
    Excel
    Also wondering if it is just low on gas, maybe it has some safety mechanism that stops the compressor coming on to prevent damage due to lack of lubrication. Would have expected some error code somewhere though.
     
  7. dacoobob

    dacoobob Junior Member

    Joined:
    Dec 29, 2021
    57
    31
    0
    Location:
    Kansas City, MO
    Vehicle:
    2016 Prius
    Model:
    Four Touring
    some part has likely failed: either the compressor itself, or the start capacitor, or the relay that turns it on. if you have a multimeter you should be able to chase down which component is busted-- test ohms on the relay coil and compressor windings, and test the capacitance (in microfarads) of the capacitor.

    if you don't want to mess with it yourself, take it someplace to be diagnosed.

    if it's the relay or capacitor, it's a super cheap fix. it it's the compressor, prepare to pay.
     
  8. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    97,739
    44,337
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    here's the compressor, but i can't find a pic of the engine bay:
    60-03675_NC
     
  9. The Professor

    The Professor Senior Member

    Joined:
    Apr 5, 2018
    564
    758
    0
    Location:
    UK
    Vehicle:
    2017 Prius
    Model:
    Excel
    Thanks all. Really appreciate the help.

    Toyota don't make it very obvious where the Relay is for the compressor. Spent the last hour on Google.

    Anyone know which Relay it is?

    One thing I have noticed is that I'm not hearing a click when I turn the A/C on and off, which is why I'm hoping it's a fuse or relay. Found plenty of fuses related to the air con (all low amperage), and one 40 Amp one which is OK, but no relay.
     
  10. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

    Joined:
    May 12, 2018
    4,667
    4,637
    1
    Location:
    Pennsylvania
    Vehicle:
    2018 Prius c
    Model:
    Two
    Low pressure cutout switch. Yes, that's quite normal in virtually all automotive A/C systems.

    That's a heck of a lot less normal. Historically auto HVAC systems just don't do that. However, the Prius does have a sophisticated air conditioner with its own diagnostic system.

    It doesn't really have a warning indicator; you have to ask it what is wrong. I can't remember the secret handshake but once you hold the right sequence of buttons the display will change and might give you useful info.
     
  11. The Professor

    The Professor Senior Member

    Joined:
    Apr 5, 2018
    564
    758
    0
    Location:
    UK
    Vehicle:
    2017 Prius
    Model:
    Excel
    Hoping it's just gas needed then. That would make sense as not hearing a relay click may be due to the fact the ECU isn't asking to turn it on due to low pressure. Hope so!

    The lack of ODBII warning may be just down to the fact it doesn't show on the normal ODBII and needs the TechStream or such like?
     
  12. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

    Joined:
    May 12, 2018
    4,667
    4,637
    1
    Location:
    Pennsylvania
    Vehicle:
    2018 Prius c
    Model:
    Two
    Prius HVAC doesn't have the traditional relay that you might be looking for. Regular cars typically had a relay to control the compressor clutch, and that relay was a common failure point. Prius has no AC clutch and therefore no relay.

    There could be a different relay involved, but it won't be anything like the common 12v style in the fusebox of any other car.

    Prius HVAC is different from other cars; if you take it into a general AC shop for re-gas make sure they realize it's a Prius; different tools and procedures required.

    The HVAC controller is separate from the main ECU and does not participate in OBDII communication. Any errors detected by the HVAC system stay within it. You can push a pattern of buttons in the cabin and the display will give you a readout; not sure if techstream can see the same stuff.
     
  13. The Professor

    The Professor Senior Member

    Joined:
    Apr 5, 2018
    564
    758
    0
    Location:
    UK
    Vehicle:
    2017 Prius
    Model:
    Excel
    Thank you.

    I tried looking through the menu described here: Service Menu Prius 2016 | PriusChat
    ...but didn't see anything A/C related. Was there another screen you were thinking of? Or did I miss it?
     
  14. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

    Joined:
    May 12, 2018
    4,667
    4,637
    1
    Location:
    Pennsylvania
    Vehicle:
    2018 Prius c
    Model:
    Two
    More like this

     
    Mambo Dave likes this.
  15. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    16,895
    11,515
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    I agree it's convenient to ask the A/C itself for its own codes. In Gen 2 and 3, you do that by turning the car on while holding the AUTO and FRESH/RECIRC buttons. I haven't looked up the specific procedure in Gen 4, but I would not be surprised if it's the same. (In Gen 1 it was different, you'd press the A/C button 3 times then turn the fan knob from OFF to AUTO).

    At the same time, I don't think it's the case that you can't get the codes on an OBD-II scan tool. In the generations I'm familiar with, the scan tool will show a trouble code B14xy where xy is the two-digit code you would get from the HVAC control itself.

    So, for me, the main attraction of the built-in HVAC code display is just that you can do it when your scan tool isn't handy.
     
  16. The Professor

    The Professor Senior Member

    Joined:
    Apr 5, 2018
    564
    758
    0
    Location:
    UK
    Vehicle:
    2017 Prius
    Model:
    Excel
    Thanks... Getting somewhere now...

    Holding down Recirculation and Auto while pressing the Start button twice (no brake) makes it display stuff.

    The number 23 and the green light on the Driver Priority button (bottom left) flash every second. 23 is not the temperature I had set so I'm guessing as that's non-zero it's end error code?

    It fits as I found a thread on here about the Gen1 that's says:

    "Gen 1 code 23 refers to signals from the pressure switch. Either there is an open in the wiring to the switch somewhere, or the switch is faulty, or the pressure really is below 28 psi or above 455 psi."

    And another for the Prius C that says:

    "DTC B1423/23 Pressure Sensor Circuit Detection Condition
    • Open or short in air conditioning pressure sensor circuit
    • Refrigerant pressure on the high pressure side is extremely low (0.19 MPa (2.0 kgf/cm 2 , 28 psi) or less) or extremely high (3.14 MPa (32.0 kgf/cm 2 , 455 psi) or more)."
    It's the same meaning for Lexus and Jaguar. Jaguars additionally display "Refrigerant pressure switch malfunction or refrigerant pressure low"

    So I'm still hopeful it just needs a top up.

    Would it be worth asking the dealership to add a UV fluorescent dye with the gas so if there's a leak somewhere we can find it?

    Any other thoughts from you lovely helpful people?


    PXL_20220323_230338475~2.jpg
     
  17. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    16,895
    11,515
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    If you go to the dealer, they will probably think of that themselves, but there's no harm in asking.

    They'll probably go systematically, look at the pressure reading in Techstream to see if the 23 was posted because of low pressure or high pressure. If, as you'd guess, it's low, they'll probably want to rule out a leak, one way or another.
     
    Mambo Dave likes this.
  18. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    97,739
    44,337
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    i would think it would be well worth it, as 6 years is way too short a time to lose that much refrigerant
     
    Mambo Dave likes this.
  19. dacoobob

    dacoobob Junior Member

    Joined:
    Dec 29, 2021
    57
    31
    0
    Location:
    Kansas City, MO
    Vehicle:
    2016 Prius
    Model:
    Four Touring
    if the pressure switch is tripping without the compressor turning on, it indicates that the system is flat (all the refrigerant has leaked out). you'll need to take it someplace to have them find and repair the leak, then refill it with new refrigerant.

    it's possible that the pressure sensor itself failed, that would be the best case scenario. but more likely it's working as intended, preventing the compressor from running on an empty system and doing even more damage.
     
  20. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

    Joined:
    May 12, 2018
    4,667
    4,637
    1
    Location:
    Pennsylvania
    Vehicle:
    2018 Prius c
    Model:
    Two
    They'll take their own pressure readings, and if they confirm the system is empty they will likely fill it with a gas cheaper than refrigerant just to see if there's an active leak to be patched.

    I didn't realize the newer versions of the car could forward error codes into the OBDII system. Figured it was still islands like in the past. That's nifty progress!
     
    Mambo Dave likes this.
Loading...