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  1. #1
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    4 ton split unit ac problem



    hi every one
    i got 4 ton split unit ac from general type heat and cool
    with damaged compressor
    so i replaced it with new one from some LRA and size
    i checked compressor before installing so compressor worked properly
    but when i started charging system i encountered this problem
    if i charge the system with required amount of ***** by weight the compressor starting opening safety valves
    but if charge system with little amount of ***** by weight the compressor and system work propely
    i tried anothre types of ***** 22 and i made clean for the system and i changed the filter and expansion valves
    i checked the electrical connection they are properly connected
    can any one help me


    Power consists not in being able to strike another but in being able to control oneself when anger arises

  2. #2
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    Well, you do have a head start...


    You are online.

    Do a quick search for air condition or refrigeration engineers in your neck of the woods and ask one of the local guys to sort it out for you.

    Sorry, but there is a whole can of worms there that needs specialist knowledge to sort out.

  3. #3
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    Re: 4 ton split unit ac problem

    ok
    what is the cause of head start
    what is the solution
    can you advice me
    Power consists not in being able to strike another but in being able to control oneself when anger arises

  4. #4
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    Re: 4 ton split unit ac problem

    the" head start" viking is referring to is the fact that you have access to knowledge- as long as you are able to provide us with more information like standing pressures,running pressures and compressor running currents- also superheat and subcooling values would be handy too.
    Quote Originally Posted by kefah View Post
    ok
    what is the cause of head start
    what is the solution
    can you advice me

  5. #5
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    Re: 4 ton split unit ac problem

    hi install monkey
    sorry for misunderstanding
    ok i will check these info and answer you later
    Power consists not in being able to strike another but in being able to control oneself when anger arises

  6. #6
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    Re: 4 ton split unit ac problem

    but can you tell me why compressor couild open its safety valves
    if there is no blockage or overcharged gas or compressor weakness
    Power consists not in being able to strike another but in being able to control oneself when anger arises

  7. #7
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    Re: 4 ton split unit ac problem

    4 ton- 14kw general- heat and cool- heatpump-(4 way valve)- do you have the model numbers of the old and new compressors, when you say you tested the newer compressor- you ran it on a bench to check pumping/operation
    safety valve you are referring to the internal relief disc- to bypass discharge gas back into the compressor body.
    changed drier and expansion valve - did you vac the system to under 2 torr, did you use nitrogen to purge whilst brazing and again to pressure test the system. - when the comp starts foes the internal relief valve open within 10seconds then its either a weak relief valve,,or overcharged due to non condensibles-air/moisture or the reversing valve is jammed

  8. #8
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    Re: 4 ton split unit ac problem

    i think new compressor was from same type of the old one
    i made a properly vacuum
    i tested system for leakage
    compressor suction and discharge were so good
    Power consists not in being able to strike another but in being able to control oneself when anger arises

  9. #9
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    Re: 4 ton split unit ac problem

    Maybe what killed the old compressor is trying to kill the new one?
    Mostly found in Oxfordshire, UK :)

  10. #10
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    Re: 4 ton split unit ac problem

    hi
    i checked the split unit
    4 way valve working properly
    the problem start when charging reach 40 psi
    discharge and suction connection both are not cold
    Power consists not in being able to strike another but in being able to control oneself when anger arises

  11. #11
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    Re: 4 ton split unit ac problem

    at 39psi suction ,whats your discharge pressure?

  12. #12
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    Re: 4 ton split unit ac problem

    i didnt check dis press
    i know the problem start when suction connection start cooling
    Power consists not in being able to strike another but in being able to control oneself when anger arises

  13. #13
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    Re: 4 ton split unit ac problem

    did you vac both sides of the system?-(hi and low )- leave gauges connected and charge via the low side - if r22 charge as a vapour if 407c or 410a then charge as a liquid slowly to allow refrigerant to boil off in your gauge line to prevent compressor damage
    Quote Originally Posted by kefah View Post
    i didnt check dis press
    i know the problem start when suction connection start cooling

  14. #14
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    Re: 4 ton split unit ac problem

    hi every one
    thank you for helping me
    i detected the cause of damaging compressor
    the problem happened because of a device in indoor unit
    the device is looks like expansion valve located in the discharge line in begining of indoor unit which is branching into the smaller pipes to the ervaporative coils.
    since i didnt use netrogen to cleaning pipes
    i only vacuumed it
    after opening it by welding it was containing alot of slug and corrosion
    so i changed it
    thank you again
    and sorry if made you tired with me
    your replays helped me in solving problem
    Power consists not in being able to strike another but in being able to control oneself when anger arises

  15. #15
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    Re: 4 ton split unit ac problem

    well done- we all learn on here!

  16. #16
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    Re: 4 ton split unit ac problem

    thank you master for helping me
    but i have question
    if i have dirty system how i can clean it
    by nitrogen or by what
    Power consists not in being able to strike another but in being able to control oneself when anger arises

  17. #17
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    Re: 4 ton split unit ac problem

    if the system is clogged- then degas from both sides of the system.cut out the drier- blow nitrogen down the suction line for a few minutes this will move any crap and exit the system at the open end where the drier was,and again add nitrogen into the discharge side again for a few minutes to clear crap again out where the drier was. then fit a new drier but slowly add nitrogen into the high side and leave the low side gauge connected to the system but disconnected from ur gauges- the nitrogen that passes through the system is verly low - not hissing , then vac and recharge with new gas- if the nitrogen is too much then youll struggle to braze the new drier in

  18. #18
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    Re: 4 ton split unit ac problem

    thank you man you helped me

  19. #19
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    Re: 4 ton split unit ac problem

    Use a BURNT out FILTER at the suction line before the compressor

  20. #20
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    Re: 4 ton split unit ac problem

    what you mean by burnt out filter

  21. #21
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    Re: 4 ton split unit ac problem

    Quote Originally Posted by kefah View Post
    what you mean by burnt out filter
    A burn out drier has a different filter in it to adsorb acid etc caused by a compressor burn out.
    Mostly found in Oxfordshire, UK :)

  22. #22
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    Re: 4 ton split unit ac problem

    thank you every one

  23. #23
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    Re: 4 ton split unit ac problem

    suction burn out drier is fitted as close to the compressor on the suction line- then regular checks of the pressure drop accross the drier-note they are meant to be removed after a while-but no one usually removes em

    every time u do a compressor change do an acid test on the oil- if acidic then fit the suction burn out drier- also acid away - is a neuraliser u can add to the new compressor prior to fitting

  24. #24
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    Re: 4 ton split unit ac problem

    I usually use one or two size bigger than needed , to your case a 10 ton will be good.
    So you do not have to worry about pressure drop.

  25. #25
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    Re: 4 ton split unit ac problem

    thank you every one

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