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  1. #1
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    Mitsubishi City Multi



    Dear sir,I got a problem with aa insufficientheatting on Mitsubishi PUHI P200YGM-A on aR410A refrigerant.The Sistem doesn't display any error cod,but the temperature which is blown from the indoor unit is approximately 28 degrees.On a low side pressure is 90 PSI and on a high side is 300 PSI.It will rise the temperature of condesation up to 33 degrees for a 4-6 minutes and will drop to 24 degrees.It works like that all the time.Best regards
    Last edited by Brian_UK; 11-02-2017 at 04:14 PM. Reason: Post moved to correct section



  2. #2
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    Re: Mitsubishi Sity Multi

    Is the problem with the only one indoor unit?

  3. #3
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    Re: Mitsubishi Sity Multi

    check the ratio of indoors to outdoors- turn a few indoors off to see if it cures it- could be diversity

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    Wink Re: Mitsubishi Sity Multi

    it- could be diversity
    Aren't they a dance band? 😂
    I'm back on the Pale

  5. #5
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    Re: Mitsubishi Sity Multi

    The problem is on all units,it is fife unit in the sistem and I tried to turn off few of them,but it is the same situation.Blowing temp.don't want to change.I want to emphasises sistem was ok a month ago.

  6. #6
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    Re: Mitsubishi City Multi

    Reclaim the refrigerant, weigh it and compare with the charge the system should hold.


  7. #7
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    Re: Mitsubishi City Multi

    I did it and even I changed refrigerant with new quantity without any result.
    Last edited by Zoran_Popovski; 14-02-2017 at 09:26 PM.

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    Re: Mitsubishi City Multi

    20bar on heating is too low, something is stopping the system from ramping up. Check the discharge temperature and discharge pressure (transducer). Connect your gauges to the system and confirm the readings are the same.
    The difference between genius and stupidity is that genius has its limits.

    Marc

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    Re: Mitsubishi City Multi

    When the sistem start discharge pressure is between 20-22 bars,but after 10 minutes pressure will go down to 15 bars and will stay there.Is there any possibility of filter clogged or compresor become weaker?

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    Re: Mitsubishi City Multi

    Quote Originally Posted by Zoran_Popovski View Post
    When the sistem start discharge pressure is between 20-22 bars,but after 10 minutes pressure will go down to 15 bars and will stay there.Is there any possibility of filter clogged or compresor become weaker?

    There are several things that will prevent the compressor from ramping up to achieve target condensing temperature/pressure - one of these is the discharge temperature.
    Have you checked this? This can be done by the dip switches on the outdoor PCB.
    As I've posted above - also confirm the pressure transducers are reading the correct value. It could be that the system thinks that it's running at 28bar (for example) because the discharge transducer is readibg 6-7bar out.
    If you come back with this answer then we can work through the problem with you.
    This needs to be checked before worrying about clogged filters in the system.
    The difference between genius and stupidity is that genius has its limits.

    Marc

  11. #11
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    Re: Mitsubishi City Multi

    If the system drops back down to 15 bar after 10 minutes then 1 of two things are happening.
    1) The system sees that there is no load/demand
    2) The board is telling the compressor to reduce the frequency of the compressor because something is wrong.

    Most likely it's No2 and the first thing to check would be the discharge temp sensor and confirm the transducers.
    The difference between genius and stupidity is that genius has its limits.

    Marc

  12. #12
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    Re: Mitsubishi City Multi

    I didn't messure discharge temperature,I wil do that next and what part you call transducers?discharge thermistors?

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    Re: Mitsubishi City Multi

    And how can I check discharge temperature with the dip switch?I can't find that into the servis manual.

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    Re: Mitsubishi City Multi

    You need the service manual for that unit. In the back of the manual it will tell you which dip switches display what value.
    In the U.K. By putting SW1 (on the main outdoor PCB) dip switches 1, 3, 4 and 6 to the 'ON' position, this will show you discharge temperature as read by the system. Check this when the system first runs and watch it for 10 mins.

    The discharge pressure transducer is SW1 numbers 4 and 7 to the 'ON' position.
    The difference between genius and stupidity is that genius has its limits.

    Marc

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    Re: Mitsubishi City Multi

    Compare the pressure reading from the LED display to the reading from your gauges.
    The difference between genius and stupidity is that genius has its limits.

    Marc

  16. #16
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    Re: Mitsubishi City Multi

    OK Mark thanks

  17. #17
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    Re: Mitsubishi City Multi

    Hallo Mark
    I have got the answers you are interested in:
    - discharge temperature displayed on LED at first run is 19.7 degres,after 15 min.temp.rise to 64.5 degres
    - pressure displayed on LED was17 bars,on the gauges was16.5 bars

  18. #18
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    Re: Mitsubishi City Multi

    Quote Originally Posted by Zoran_Popovski View Post
    Hallo Mark
    I have got the answers you are interested in:
    - discharge temperature displayed on LED at first run is 19.7 degres,after 15 min.temp.rise to 64.5 degres
    - pressure displayed on LED was17 bars,on the gauges was16.5 bars
    Okay, what mode was the system in when you were measuring the discharge temperature? Going off that reading, I assume cooling mode?

    Also what was the discharge pressure when the discharge temperature was at 64.5 degrees
    The difference between genius and stupidity is that genius has its limits.

    Marc

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    Re: Mitsubishi City Multi

    I
    No,when I meassured discharge temperature sistem was heating mode in and discharge pressure was 17 bars...showan on LED display.

  20. #20
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    Re: Mitsubishi City Multi

    System was in heating mode and it was only at 17bar?

    If all indoors are on and calling for heat then something is stopping the compressor from ramping up.

    This should be a pretty simple fault if you're familiar with how these systems are supposed to work.

    Can you get hold of a service checker and upload the system readings on here?
    The difference between genius and stupidity is that genius has its limits.

    Marc

  21. #21
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    Re: Mitsubishi City Multi

    How can I be familiar with the sistem when customer calls me only when something go wrong,that is practis here and this is first time to have a problem with that sistem.No,I haven't got servis checker,eventualy to try to read displayed sistem parametars consalting the service manual.

  22. #22
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    Re: Mitsubishi City Multi

    OK,
    As you verified the refrigerant charge, the most likely cause of the system not ramping up/delivering 100% is that the controls is not seeing what is going on in the system correctly.
    One or more of the pressure transducers or temperature thermistors will either be out of calibration or not in the correct place.
    It is possible to find this without the laptop interface, it just takes slightly longer.
    The best you can do is to follow the service manual and go through all temperature and pressure readings one at a time and compare the values with what you measure the actual temperatures/pressures to be.
    One degree or two, or 1/2 a bar on pressures, will probably be OK and not affect the running of the system but if you find a reading that is 5-10 degrees, or even more, out then you probably have found the cause of your issues.

    (A "cheat" is to check all the temperature sensors after the system been off for a while, say overnight, as most temperatures in the outdoor unit, apart from measurements affected by CC heater, will be that of the ambient temperature. This makes it easy to spot any readings that stands out)

    Also be aware that when thermistors fail they might show the correct temperature / resistance from time to time but go out of calibration if they get wet/get moisture inside, making them harder to spot.

    Another thing to look out for is running currents, a loose connection or poor power supplies might increase the running current and this might also limit the compressor speed.

    Last edited by The Viking; 17-02-2017 at 08:29 PM.

  23. #23
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    Re: Mitsubishi City Multi

    I will do this suggestions step by step and inform you about the results...While I reading all this something fell on my mind,discharge sensor,the seal,where the cabel get into the coper,was broken.Do you mean that might be a potencial problem or one of the problems?

  24. #24
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    Re: Mitsubishi City Multi

    If the discharge transducer/sensor cable was broke, you wouldn't get the reading that you did, it would also generate a fault code.
    The difference between genius and stupidity is that genius has its limits.

    Marc

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    Re: Mitsubishi City Multi

    Ah, but if the silicone is cracked moisture will get in and this will from time to time give incorrect readings.
    Normally not on discharge transducers as they are warm enough to get rid of the moisture but the principle still applies.

    Good practice on systems that are a few years old is to check the transducers as part of the annual service and replace the ones where the silicone seal is broken. Prevents a lot of hassle.


    Last edited by The Viking; 19-02-2017 at 12:14 AM.

  26. #26
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    Re: Mitsubishi City Multi

    Agreed.
    I'd suggest that you put 'ALL' of the indoors on test mode heat. Get hold of the service manual and follow the refrigerant flow checking transducers, 4way Rv, solenoids and thermistors along the way.

    Double check the HP transducer and Sensor again ( it might be worth double checking the Dip switch settings because I gave you the ones for the U.K. Version, in Macedonia they might be slightly different).
    Other things to look for would be low pressure, sensor and transducer, compressor speed, target condensing temperature, P1 and P3 sensors (in the BC box), these should be between 3-4 bar ideally.

    I know it sounds like a lot of things to check but without this type of information it's difficult to know what is stopping it from ramping up.
    The difference between genius and stupidity is that genius has its limits.

    Marc

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