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A/C Amplifier Location

Discussion in 'Gen 2 Prius Technical Discussion' started by jerlands, Jun 7, 2019.

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  1. Skibob

    Skibob Senior Member

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    If the problem has started since he’s owned the car then the first thing I would do is pull the non working fan and check it for continuity, plus check the plug for power (in parallel). Wires do get damaged but check the easy stuff first.
     
    #41 Skibob, Jun 18, 2019
  2. jerlands

    jerlands Member

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    I'm not convinced of anything :) I'm just trying to understand this system so I can develop some sort of battle plan...
     
    #42 jerlands, Jun 18, 2019
  3. jerlands

    jerlands Member

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    I understand and agree with everything you say... except maybe the thing about the proton being given a positive charge arbitrarily because I'm not certain the name itself didn't have something to do with it... proton meaning something like principle or first? I've always thought that would be a positive thing rather than a negative :)
     
    #43 jerlands, Jun 18, 2019
  4. Skibob

    Skibob Senior Member

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    I did find it interesting that the 2 fans run in both series and parallel, I didn’t know that. Good luck with your battle plan. Mine would be if both fans are supposed to run at the same time and don’t I would figure out why and fix it. If the one remaining dies then you have none.
     
    #44 Skibob, Jun 18, 2019
  5. jerlands

    jerlands Member

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    I looked it over again and I have two fans running and also the steering wheel recirc control is back. A problem still exists however in that it doesn't seem to be cooling well enough but it is cooling. I also ran the onboard diagnostic and only came back with the passenger side solar sensor and the active "electric fan" test in Techstream ran both fans but only at one speed. Apparently there isn't a way to test the high speed but it seems the high speed is signaled (relay #2) by either the ECU, the pressure switch (which I guess senses HP side) or the amplifier. Whatever problem I have is intermittent so it would seem like a short of some kind but I also wonder if it isn't an electronic issue?

    Also, I don't know all the implications but I've heard about a failing 12v battery and spooky action at a distance (strange electrical things going on?) I know this 12v battery was replaced but I can only guess right now why and that thought keeps poking me (and along with the experience of my HV battery failing :)
     
    #45 jerlands, Jun 18, 2019
    Last edited: Jun 18, 2019
  6. ChapmanF

    ChapmanF Senior Member

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    Well, that's interesting. I'm not as much into the 12 V battery spooky action at a distance as some others here ... there are certain obvious things likely to happen if the battery voltage is crazy low (like, all motors run slow and headlights-glow-orange low, though that doesn't work with LED or HID headlights!), but it's not a story I reach for anytime the car does anything I haven't explained.

    My lifetime estimates for different causes of electrical system funkiness in cars have ended up something like: corroded connectors 40%, switch contacts, potentiometer sensors, etc., 40%, relays, motor brushes, and other electromechanical things that move and wear out, 18%, all other causes except electronic controls, 1.9999%, ECUs going bad, 0.0001%.

    Or something like that. Of course I just made the numbers up, but they give the overall shape of my experience.

    That depends on what the easy stuff is. Maybe the fans got easier to take out in Gen 2, I haven't tried. In Gen 1, the instructions are to drain the coolant and recover the A/C refrigerant and move all the plumbing out of the way so the fans can come out ... which probably means if I had a multimeter and a wiring diagram handy, I'd be checking other stuff first (even finding the other ends of the wires that run to the buried fans, and checking them from there).

    Hmm, maybe you're thinking of 'Prius'. :D
     
    #46 ChapmanF, Jun 18, 2019
  7. Skibob

    Skibob Senior Member

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    I do have to say I have never removed the fans on my Prius. Never had to do all that on any other car I owned. :whistle:
     
    #47 Skibob, Jun 18, 2019
  8. jerlands

    jerlands Member

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    That's Latin... I'm talkin' Greek :LOL:
     
    #48 jerlands, Jun 18, 2019
  9. jerlands

    jerlands Member

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    I'm gonna wait for the steering wheel recirc control to fail again then check to see if the radiator fan runs with the AC on or with Techstreams Active Electrical Fan test (which it wasn't doing in the past.) The only thing linking the two seems to be the amplifier... and I don't know what conditions cause the amplifier to output any signals at all... without guessing... I guess I'll have to find the inputs to the amplifier to know what it might measure and output?

    Edit: I think I found all the information about the amplifier in the AC service manual :) and all it says about the fans is... Electric Cooling Fan Control... The air conditioning amplifier control the cooling fan in accordance with the vehicle speed signal and compressor speed signal.
     
    #49 jerlands, Jun 18, 2019
    Last edited: Jun 18, 2019
  10. ChapmanF

    ChapmanF Senior Member

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    Or you might save some time by considering its only possible outputs, covered already in this thread.

    You should be at least peripherally aware of your assumption that two things have to be linked. Some of the situations that end up taking the longest to solve are those where really two independent things have happened, and you think yourself into a tizzy trying to fit them with one explanation.
     
    #50 ChapmanF, Jun 19, 2019
  11. jerlands

    jerlands Member

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    I'll have to see how the test goes... if both the steering wheel control and the engine fan fail together again I think that might indicate something?
     
    #51 jerlands, Jun 19, 2019
  12. jerlands

    jerlands Member

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    I'm trying to keep issues separate but they seem to arise at the same time... except for the fact the AC doesn't work well and works less well when these issues appear...
     
    #52 jerlands, Jun 19, 2019
  13. jerlands

    jerlands Member

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    if there were no wiring fault and no fan fault would there then be a reason for only the AC fan to run? I don't fully understand how this system works because there are conditions I don't see and this is where I'm at now. confused :) I imagine the ECU only signals for high speed operation due to engine temperature but I have to review the service manual to see if something isn't explained. the pressure switch seems easy enough but the amplifier is still a mystery to me...

    what does seem different to me in how the amplifier should operate is things like the following that I've never noticed working?
    1.) Warm-up Control:
    • When the air outlet is in the FOOT, BILEVEL,
    or FOOT/DEF mode, the blower
    will not operate until the engine coolant
    temperature increases above a
    prescribed value. When the temperature
    increases above a prescribed value, the
    blower motor operates at the LO speed.
    2.) Time-Lagged Air Flow Control:
    • 2 types of time-lagged air flow control (in
    accordance with the detected by the
    evaporator temperature sensor) help
    prevent hot air from being emitted from
    FACE or BI-LEVEL vent.
    3.) Sunlight Air Flow Control:
    • Controls the blower speed in accordance
    with the intensity of the sunlight when the
    air outlet mode is at FACE or BI-LEVEL.
    The blower speed can be adjusted in
    response to the signal received from the
    solar sensor.
     
    #53 jerlands, Jun 19, 2019
    Last edited: Jun 19, 2019
  14. ChapmanF

    ChapmanF Senior Member

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    Say, have you checked yet which of the two fans is running when it's only one? That would be useful information. You can distinguish them by the color codes of the wires attached.

    If you ask the wiring diagram a better question (like "what could cause this fan to run and not that one" instead of just "what would cause one fan to run and not the other"), it can give you a better answer.
     
    #54 ChapmanF, Jun 19, 2019
  15. jerlands

    jerlands Member

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    But I think how the service manual describes the operation of the amplifier in respect to the fans...

    Electric Cooling Fan Control: The air conditioning amplifier control the cooling fan in accordance with the vehicle speed signal and compressor speed signal and both of these seem to originate from the ECU?

    The Combination Meter ECU sends vehicle speed signal to Amplifier...
    (I don't see a location for this so I assume it's part of the Hybrid Control ECU?)

    The Hybrid Control ECU sends compressor speed signal to Amplifier...
     
    #55 jerlands, Jun 19, 2019
  16. jerlands

    jerlands Member

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    The wires going to the fan on the motor side are blue and black. I'm assuming that is the engine fan (and have thought this for a while for some reason) the print on pg 347 of the wiring diagrams shows it as blue also? (I think I saw an image distinguishing the two somewhere at sometime.)

    odd though.. I had checked earlier and no longer do I have steering wheel function out of the right climate control at all. not just the recirc but also the front and rear defrost. Both fans are running and I've run the AC through some functions and it seems to be working ok now? The car hadn't been driven or the steering wheel moved since I last checked it but I had rotated the steering wheel quite a bit yesterday trying to detect a problem with the spiral cable (because it was working then.)
    well it won't tell me yet (n) I think though the amplifier could play a role but also could wiring or maybe just a sticking relay :)
     
    #56 jerlands, Jun 19, 2019
    Last edited: Jun 19, 2019
  17. jerlands

    jerlands Member

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    If the Techstream Active "Electric Fan" test is run in high speed then I could explain the loss of the engine fan during the test as amplifier related.
    but if the test is run in low speed it would indicate wiring issues...
     
    #57 jerlands, Jun 19, 2019
  18. jerlands

    jerlands Member

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    I just went out for a ride in about 90 degree weather and the AC seemed to work ok... I had it set on 74 in the cab and the blower was on one notch below hi but it had changed from a lesser setting when it was about 5 degrees cooler. and even though the RH steering wheel climate control wasn't working...
     
    #58 jerlands, Jun 19, 2019
  19. jerlands

    jerlands Member

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    in techstream I think I need to watch the AC compressor speed to see what changes it makes... and I believe that's controlled by the ECU talking to the AC Inverter?
     
    #59 jerlands, Jun 19, 2019
  20. ChapmanF

    ChapmanF Senior Member

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    Is that the one that runs, or the one that doesn't run?

    One of them is fed by a blue wire and a white-with-black-stripe wire. (Maybe you were seeing mostly the stripe?) The other one gets a green wire and a white (no stripe) wire.

    If I remember right, the system check screens available on the MFD include one for testing control switch inputs, which might include the ones on the steering wheel. I haven't had to look in a while. That could help you determine what input signals you're getting.
     
    #60 ChapmanF, Jun 19, 2019
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