A/C sudenly warm and Recirculate/defrost steering wheel buttons no longer working

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by iRunfastXC, Jul 7, 2024.

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  1. iRunfastXC

    iRunfastXC Junior Member

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    Title pretty much describes what I'm experiencing. 2004 Prius, 195k miles.

    As I was driving on the highway, the A/C went from ice cold to not cooling at all. Fan and heat work fine. Cooling has not come back since. In troubleshooting, I tried to pull codes using the steering wheel button method, but nothing ever came up. Came back the next day with a theory, and I was correct–the right side HVAC buttons are no longer working on the steering wheel (recirculate & both defrost buttons). The rest of the buttons on the wheel are working just fine.

    So that would explain why I can't pull A/C codes with the steering wheel method. The car doesn't know I'm pressing the button lol.

    Looking for ideas for:
    1. What could have caused both these issues at the same time? Buttons and A/C were working fine before that day.
    2. I do have an OBD2 bluetooth unit with various apps. Any way I could pull A/C codes without the steering wheel method? I know the A/C computer doesn't spit OBD2 codes.
    FWIW, my gas mileage is still perfectly fine. Mix of highway and city driving, last four tanks have been between 50-52 mpg, so I don't think it's an inverter issue.

    Many thanks.
     
    #1 iRunfastXC, Jul 7, 2024
  2. Tombukt2

    Tombukt2 Senior Member

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    Maybe at this mileage in your particular car it's time to replace the spiral cable behind the steering wheel they do go bad I'm not sure that would make your AC stop working if you can still control it from the MFD I wouldn't think that would be your cooling stopping problem but I guess it could be as the spiral cable is not making communication I guess it would just turn it off I don't know doesn't seem right when you take the spiral cable out of the equation and use the MFD to control the air while you're going down the road as the air conditioning working just fine now no problems?
     
    #2 Tombukt2, Jul 7, 2024
  3. ChapmanF

    ChapmanF Senior Member

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    Are you sure it doesn't?

    In gen 1 it didn't.

    This gen 2 repair manual excerpt shows them....

    https://attachments.priuschat.com/attachment-files/2018/05/146483_AC.pdf
     
    #3 ChapmanF, Jul 7, 2024
  4. Tombukt2

    Tombukt2 Senior Member

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    Yeah I've gotten AC codes many times in the generation too I can't remember what they are but they're there also for the solar sensor but I've had some AC codes in the generation too we've talked about them here before I just cannot for the life of me remember what they are and in the generation 3 I guarantee it.
     
    #4 Tombukt2, Jul 7, 2024
  5. iRunfastXC

    iRunfastXC Junior Member

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    In reading a lot of threads here, I'm fairly sure, yes, at least with a standard OBD2 reader. With Techstream, possibly.

    Much like Brake system codes (remember the old OBD2 port wire trick? Your whole dash could be lit up, but no OBD2 codes...you'd have to read the "blink" codes after connecting two nodes in the port with a wire), they spit off through a separate computer.

    I was bummed when the steering wheel button trick didn't work (holding the recirculate and auto buttons when starting up). When you do that, it shoes the codes on the MFD which associate with the codes shown on that chart in the manual you sent.
     
    #5 iRunfastXC, Jul 7, 2024
  6. iRunfastXC

    iRunfastXC Junior Member

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    Yeah, I actually never use the steering wheel buttons to control the A/C (creature of habit, I guess). That's why I didn't notice those right side buttons not working immediately. All the controls on the MDF are available, and function normally, the air just isn't cooled.
     
    #6 iRunfastXC, Jul 7, 2024
  7. ChapmanF

    ChapmanF Senior Member

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    With Techstream, definitely. With an OBD-II reader that doesn't know how to get codes from all the ECUs in a Prius, maybe not. But I wouldn't blame that on the A/C amplifier not providing the codes.

    We do have a thread reviewing a number of scan tools and identifying those that can get all the trouble codes from a gen 2 Prius:

    Gen2 OBD2 app review | PriusChat
     
    #7 ChapmanF, Jul 7, 2024
  8. iRunfastXC

    iRunfastXC Junior Member

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    Aha! That was actually quite helpful. Had to get an OBD2 adapter that supported ELM327 V2.0+ (Grabbed the VeePeak OBDCheck BLE+, which supports up to ELM327 V2.2 protocols).

    Connected to the A/C computer and got the following codes:
    1. B1421 (Not concerned about this...the car was in the shade lol)
    2. B1423: Open in Pressure Sensor Circuit / Abnormal Refrigerant Pressure.
      1. Reading up on this one in the manual you sent...If my refrigerant is low, the condenser would permanently shut off, and the computer would throw this code.
      2. Reading in the forums, it has also been a faulty pressure sensor or a blown fuse.
    Not sure what to test first :)
     
    #8 iRunfastXC, Jul 9, 2024
  9. ChapmanF

    ChapmanF Senior Member

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    I can't for the life of me imagine how a B1423 could be caused by a blown fuse. Some forum posts are very imaginative.

    Of course, it can be the pressure switch (gen 2s just have a too-low/goldilocks/too-high switch, not a sensor like gen 3) ... or the wiring to the switch ... or actually having too much or not enough of the stuff the switch measures.
     
    #9 ChapmanF, Jul 9, 2024
  10. iRunfastXC

    iRunfastXC Junior Member

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    So I guess next step would be to measure the high & low pressures, eh? I’d love it if it was just low refrigerant. Unless there’s a leak lol.
     
    #10 iRunfastXC, Jul 9, 2024
  11. Tombukt2

    Tombukt2 Senior Member

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    Yeah stick one of those silly cans with the gauge on it on the low side what's the reading with the car not running again if it's full it'll almost bury the low pressure gauge at past 80 lb turn the air conditioner on low fan on high fresh air and it should pull that low side gauge that was just above 80 lb down to about 36 maybe a little lower and then back up to 36 if that's happening you're pretty full and things are happening like they're supposed to You should be making cold doesn't mean you'll be feeling it in the car but you're making it if the duct work and the dampers aren't set right You may not see the cold in the car but you're making it that can be problematic in the grand scheme of things
     
    #11 Tombukt2, Jul 9, 2024
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