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  1. #1
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    General AOHA24LAT3



    Hi all.
    I hope that you can help.
    Interior unit is displaying; Operation - Off, Timer - 2 Flashes. (Reverse communication error).
    No LED's on exterior control PCB.
    236Vac in, and at points W4-W5, W8-W9 and TM101-TM102 on Power PCB. 236Vac at CN34 and W10-W11 on Control PCB as expected. All fuses good.
    There is 4.15Vdc across W12-W13 (Yellow-Blue to ACTPM). What voltage should I be seeing?
    There is 1.7Vdc across W16-W17 (Black-Red to ACTPM)
    Serial communication connection connected; something in the order of 20-67Vac.
    Serial communication connection disconnected; From interior unit 70-90Vac, from Control PCB -2.38Vac. Inverter tester showing communication in one direction only.
    What should I be seeing at CT connection between Power and Control PCB?
    I have attached the main current area of the wiring diagram here

    At D101, I have 2.54Vac across AC and 1.70Vdc across DC.
    At IC's 1,2 and 3 there is only 5.4mVdc across 3 and 5.
    I have tried to give as much information as possible, but I would like a more accurate diagnosis as to which component has failed. Obtaining Fujitsu/General parts here can be difficult as the easiest.
    Thanks in advance.....
    Graham


    en boca cerrada no entran moscas

  2. #2
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    Re: General AOHA24LAT3

    Quote Originally Posted by aircon50 View Post
    Hi all.
    I hope that you can help.
    Interior unit is displaying; Operation - Off, Timer - 2 Flashes. (Reverse communication error).
    No LED's on exterior control PCB.
    236Vac in, and at points W4-W5, W8-W9 and TM101-TM102 on Power PCB. 236Vac at CN34 and W10-W11 on Control PCB as expected. All fuses good.
    There is 4.15Vdc across W12-W13 (Yellow-Blue to ACTPM). What voltage should I be seeing?
    There is 1.7Vdc across W16-W17 (Black-Red to ACTPM)
    Serial communication connection connected; something in the order of 20-67Vac.
    Serial communication connection disconnected; From interior unit 70-90Vac, from Control PCB -2.38Vac. Inverter tester showing communication in one direction only.
    What should I be seeing at CT connection between Power and Control PCB?
    I have attached the main current area of the wiring diagram here

    At D101, I have 2.54Vac across AC and 1.70Vdc across DC.
    At IC's 1,2 and 3 there is only 5.4mVdc across 3 and 5.
    I have tried to give as much information as possible, but I would like a more accurate diagnosis as to which component has failed. Obtaining Fujitsu/General parts here can be difficult as the easiest.
    Thanks in advance.....
    Graham
    I've sent you an email.

  3. #3
    Join Date
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    Re: General AOHA24LAT3

    Thanks Richard
    However, I already had that information. I can't decide if the fault is with the power PCB or the control PCB.
    Graham
    en boca cerrada no entran moscas

  4. #4
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    Re: General AOHA24LAT3

    Hi Graham.
    From W10 and 11, this 240V goes through the posistor and to a diode module. If all is good further on a relay on the controller PCB will close and effectively short across the posistor so the full whack of current will flow. You have no output from the diode module (W16/17 should be high voltage DC), something is taking to much current and the outdoor is protecting itself.
    You need to disconnect all outputs from the controller PCB first (fan, EEV, probes) power up and see if the high voltage is there. If it is plug bits in one by one and note when the voltage drops. When plugging the fan in power down for a couple of mins before plugging it in.
    If high voltage DC isn't there you need to unplug black and red from ACTPM to prove this module is fine, perhaps unplug P and N just to prove the diode bridge is working in the first place.

    If you can get a service manual the PCB diagrams are there, just a case of following the voltage and unplugging wherever to prove voltage to that point. Let me know if you need a copy.

    CT looks like the current transformer, don't think that is your issue here. 5VDC across outside wires, signal in the middle. 5VDC is supplied from controller PCB but that wont be there as DC isn't reaching where it should yet.

    General faults would be fan packed up or compressor/inverter faults. Either way not a five minute job and probably deepish pockets required.

    Let me know if you need anymore explaining, it's a bit long winded but easy when you know.

    Cheers,
    Andy.
    Last edited by Tayters; 29-06-2018 at 08:17 PM. Reason: Sorry, been a long few days. Should have said that any plugging or unplugging of the high voltage DC should be done after power has been off for a couple of minutes.

  5. #5
    Join Date
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    Re: General AOHA24LAT3

    Thanks Andy
    I've got wiring diagrams. I'll get back to it, and let you know how I get on.....
    Graham
    en boca cerrada no entran moscas

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