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  1. #1
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    Faulty Fujitsu invertor wall split



    I have a friend who has A Fujitsu wall split Model: AOTR18LCC.
    When starting the unit if selecting heating the compressor starts ( No pressure changes on the guages )and after about 2 minutes it shuts down and the two lights on the left of the indoor wall split flash together 2 times and then the single light beside them ( green light ) flashes 4 times then it goes back to the two lights flashing twice and so on.
    The unit will not operate the indoor fan when just asking for the fan only and the unit dos,nt work either.
    The unit pressures seem to be ok ( Dos'nt look short of gas )Does anyone know what fault the flashing lights are showing



  2. #2
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    Re: Faulty Fujitsu invertor wall split

    Unfortunately, I don't recognize the Australian model number so I can't really comment on a possible cause.

    You have given a clue though.

    if selecting heating the compressor starts ( No pressure changes on the gauges ) and after about 2 minutes it shuts down
    No change in pressure means one of two things with the compressor running:

    1) 3 phase unit running backwards
    2) single phase comp not pumping

    Now, as the unit is a small split, I would say it was single phase so number 1) doesn't apply.

    Number 2) could be a result of:
    a) internal bypass valve open
    b) internal discharge line broken
    c) lack of oil in the scroll (assuming it is a scroll)

    Without the compressor operating correctly and creating circulation, I'm intrigued to know how the pressures seem ok?
    The unit pressures seem to be ok ( Dos'nt look short of gas )
    What are the pressures? What gas is it on? Any history on the unit?

    So many questions.

  3. #3
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    Re: Faulty Fujitsu invertor wall split

    Another likely cause would be the 4-way valve...

    As we heard some stories about the quality of installations "down there" I think it might be a case of crud in the slider of the 4-way valve.

    If you feel/measure the temperature of the suction and discharge pipes by the compressor, what happens when the compressor is running?

  4. #4
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    Re: Faulty Fujitsu invertor wall split

    Quote Originally Posted by frank View Post
    Unfortunately, I don't recognize the Australian model number so I can't really comment on a possible cause.

    You have given a clue though.



    No change in pressure means one of two things with the compressor running:

    1) 3 phase unit running backwards
    2) single phase comp not pumping

    Now, as the unit is a small split, I would say it was single phase so number 1) doesn't apply.

    Number 2) could be a result of:
    a) internal bypass valve open
    b) internal discharge line broken
    c) lack of oil in the scroll (assuming it is a scroll)

    Without the compressor operating correctly and creating circulation, I'm intrigued to know how the pressures seem ok?


    What are the pressures? What gas is it on? Any history on the unit?

    So many questions.
    I'm a frigie by trade.The reason why I mensioned the gas was that the pressures in the system when off seemed to look ok in relation to a gas leak.Yes the compressor dos'nt look like it's pumping and that would mean that the temp on the indoor coil would not be rising thus not turning on the indoor fan.But why when just selecting the fan onlone will it not start.I'm not familiar with Fujitsu units as we don't install them on our jobs as I'm not a big fan.

  5. #5
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    Re: Faulty Fujitsu invertor wall split

    Quote Originally Posted by nick_nst@aapt.n View Post
    I'm a frigie by trade.The reason why I mensioned the gas was that the pressures in the system when off seemed to look ok in relation to a gas leak.Yes the compressor dos'nt look like it's pumping and that would mean that the temp on the indoor coil would not be rising thus not turning on the indoor fan.But why when just selecting the fan onlone will it not start.I'm not familiar with Fujitsu units as we don't install them on our jobs as I'm not a big fan.
    Hi Nick

    You can't tell if a system is charged correctly just by looking at the pressures when the system is off.

    A gas leak can be large or small and some leaks don't show up for a few months, that's how small they can be. (gradual loss of performance)

    On a cooling air conditioner or a fridge system, the indoor coil always goes colder when the system is running.

    On a Fujitsu AC unit, if the system is in fault, nothing will work until the fault is fixed, that's why it won't work in 'fan only'

  6. #6
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    Re: Faulty Fujitsu invertor wall split

    the comp is three phase. make sure you have 3phase from your inverter pack 1st before shooting the comp down

  7. #7
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    Re: Faulty Fujitsu invertor wall split

    I think we'll end this conversation.I don't need to be told that system pressures change when system in running operation.If a qualified frigie or even a second year apprentice dos'nt know that there's going to be problems in the future.When your looking at a reasonable pressure in the system while the compressor is off the system should not be locked out on low pressure fault after reseting the lock out relay or circuit.After resetting any lockout faults the system , the operator should be able to start the indoor fan without any heating or cooling selected.I would also hope that any qualified mechanic would not believe that the refrigerant charge was correct without the machine running and have return air temps and ambients to compare.If a Fujitsu unit will not work at all until the fault is fixed tell me why the compressor runs.Then again don't bother as you sound like an engineer who reads from a book.
    If you intend on trying to help people in the future read the problem correctly before typing any stupid smart ass comments

  8. #8
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    Re: Faulty Fujitsu invertor wall split

    Which side of the bed did you get out of this morning?????

    If you are so clever that you don't need the advice of others then why did you post the question????

    Excuse me for replying.

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