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AC issue: doesn't switch to recirculate, only old occasionally

Discussion in 'Gen 2 Prius Technical Discussion' started by R-P, Jun 14, 2017.

  1. R-P

    R-P Active Member

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    Only Cold occasionally... How does one change the title??? :eek:

    Wife had the car, complained it didn't get cold and didn't automatically switch to recirculate this morning.

    This afternoon everything was OK (AC worked, it blew cold air, do not know about the recirculation setting).

    Did some searches:
    Found two conflicting threads I think, (bubbling seen through small window under the bonnet somewhere "is enough coolant" or it "is NOT enough coolant").

    Or it is simply some 10A fuse (since it worked this afternoon, that idea went out the window again, might still be a contact issue if all symptoms fit).

    Other ideas:
    What are the symptoms when the 20k resistor for an aftermarket headunit looses contact? That might be the case, don't remember if I just jammed it in or soldered it correctly (I think the latter)).

    Does it always switch to recirculate when pushing the AC button on the steeringwheel? We think it does, but may only be when it is realy warm outside (which it wasn't this morning).

    Is the refrigerant likely just low and is a quick check in order (to prevent possible compressormalfunction and $1000 bills...)?

    Any thoughts welcomed.

    Some more semi-off-topic jibberjabber to make sure this post isn't short and to-the-point, as that is not my style...:
    Our other car (Volvo V70) has had a broken evaporator AND condensor for the last 7 years :cry:, but given the hot days we are having here lately, we need at least one working AC...
    All trips to Italy in the last years (>>40C/110F...) have been in the Prius instead of the much bigger trunked Volvo.with our family of 5... I have been meaning to tear out the entire Volvo dash (lots and LOTS of work supposedly, making the car unuseable for a week, but needed for the condensor iirc) for years and will in a few weeks since the intercooler now also packed in (still drives, but probably not for long before it starts throwing codes and running in limp-home-mode). But mounting the 5kW solarpanels comes first (deadline: before the solar solstice :D)
     
    #1 R-P, Jun 14, 2017
    Last edited: Jun 14, 2017
  2. ChapmanF

    ChapmanF Senior Member

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    Two different accounts might have been conflicting just because the correct observation depends so much on ambient conditions. You can find the section in the repair manual setting out how to interpret the sight-glass observations, and also pressure readings on a gauge set, and you'll see they specify the conditions right down to the ambient temperature, the fan setting, and which doors are open. Under the specified conditions, if I remember right, a proper fill was something like 150 g more refrigerant after the last bubbles disappeared. (Don't rely on me for that; that was purely from memory.) But change the operating conditions and the expected observations change too.

    Of course any gas has a strict temperature/pressure relationship (Boyle's law, after all) and points at which it liquefies or vaporizes ... but A/C refrigerants are chemicals chosen for having all of that going on in the exact range of pressures and temperatures the car A/C will operate in, so it's no surprise the details are so sensitive to the conditions.

    Have you read the trouble codes from the A/C unit yet? I'm not sure of the procedure on a Gen 2; I think I may have read it's the same as Gen 3, that is, hold down the AUTO and RECIRC buttons while turning the car power to ON, then look for two-digit numbers in a top corner of the display.

    -Chap
     
    #2 ChapmanF, Jun 14, 2017
    R-P likes this.
  3. R-P

    R-P Active Member

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    21 and 43. I'll try to find what they mean.

    I pushed the recirc and auto button and switched ON the 'starterbutton'.
    All symbols in the climate window flashed for a few seconds (after the MFD startup-screen) and then 21 and 43 alternated in the top right corner.

    21 supposedly means the lightsensor is in the shade...


    Found here:
    Air Conditioning System - Toyota Avalon Repair - Toyota Service Blog

    B1443/43

    Air Outlet Damper Control Servo Motor Circuit

    1. Air outlet control servomotor

    2. Air conditioning harness assembly

    3. A/C amplifier

    Memorized (30 sec. or more)

    AC-78

    No clue what it means, will update if I find out.
     
    #3 R-P, Jun 15, 2017
    Last edited: Jun 15, 2017
  4. ChapmanF

    ChapmanF Senior Member

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    There was a very recent other thread where someone had some codes and looked them up in manual excerpts found online that turned out to be for different cars (one of them was indeed for a Prius, but the wrong generation), and that turned out to be the explanation of the inconsistent/conflicting information that poster was asking about. I'm told I came across as rude or snide in pointing that out, which I regret, but I do want to point out that can happen; they don't build all the car models exactly the same.

    I don't know whether 43 means the air outlet servo across their whole line of vehicles. It seems unlikely they would change the correspondences. But it might be worth checking, since you didn't describe any issue with the outlet servo, and you did describe something with fresh/rec.

    The one sure-fire way to get the information that will be correct for your model and year is to go to techinfo.toyota.com and look it up for your model and year.

    -Chap
     
    #4 ChapmanF, Jun 15, 2017
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