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  1. #1
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    Daikin L9 error code RXYSQ4M7V3B



    Hi all

    I have the machine mentioned in title. Was installed second hand and couple of issues getting going - a U4 error and another which i forget but i think was pcb related. Then it started working and was cooling ok.

    The system is 12.5Kw but we have about 8 indoor units amounting to 17.5Kw. We didnt have them all on at the same time. Pipework is spread accross 6 floors. It worked ok for about a week but then last week with the hot weather it was failing. I would turn off outdoor unit, leave for a while and then hold reset and power cycle. That fixed it a few times but then it died and we were left with L9 code and the fans and compressor arent coming on (lights are on though).

    As far as i can determine, this means we have either a faulty inverter pcb or refrigerant loss or maybe dead compressor. The refrigerant was just checked so that should be ok. It appears that the PCB is a common problem so i wonder how you check that other than just replace it (if you can find one).

    What advice does anyone have for troubleshooting without spending lots of money?

    Many thanks
    Ash



  2. #2
    Brian_UK's Avatar
    Brian_UK is offline Moderator I am starting to push the Mods: of RE Site Moderator : and general nice guy
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    Re: Daikin L9 error code RXYSQ4M7V3B

    Do you consider employing a qualified aircon engineer expensive? If not then do so.

    Otherwise the unit service manual should give you the diagnostic routines to follow.
    Brian - Newton Abbot, Devon, UK
    Retired March 2015

  3. #3
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    Re: Daikin L9 error code RXYSQ4M7V3B

    Thanks for replying Brian.

    Its kind of complex. Yes i could employ one but what i need to do is demonstrate to the one that installed it what to do next. His advice (based on the error code and there beng too many interior units) is to buy a new unit since if it is a pcb then it requires 3 pcbs and then the compressor may still be at fault or may fail within x months, making the purchase of new unit more cost effective in the long run.

    I just want to see if it is possible to diagnose the problem without deep AC knowledge. If i had a service manual then maybe i could do it myself if it didnt require specialist tools.

    Cant afford a new unit right now but checking ebay for similar - or actually bigger to accommodate the actual potential draw on the system should we have all internal units running. But before i go down that route it seemed a proper investigation was worthwhile - this is from years of engineering support (different field).

    Cheers

  4. #4
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    Re: Daikin L9 error code RXYSQ4M7V3B

    How was the gas charge checked?
    to me this sounds like a job that has being hobbled by cost.
    not good road to travel.
    we. Went to job like this,ripped the lot out,only a few years old it was.
    A replaced it with. The correct kit for the job.

  5. #5
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    Re: Daikin L9 error code RXYSQ4M7V3B

    L9 is compressor lock. You can put the field setting in to check the inverter pcb. But daikin always advise to replace both pcb and compressor. I'd say stop trying to save money as it will cost you more in the long run. Get a professional in

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