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  1. #1
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    high pressure switch and solenoid valve

    hi
    i have lg 24000 btu split ac unit
    there is high pressure switch and solenoid valve
    Name:  Snap_2013.04.25_20h00m01s_001.jpg
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    the both the solenoid valve and hi pressure switch are wired to the outdoor fan
    the solenoid installed to the suction pipe of condenser
    the hi press switch connect between capillary tube and the discharge of the compressor
    what is the utility of them

  2. #2
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    solenoid valve opens when there's a call for cool, and high pressure switch trips when the discharge pressure is too high, the reason it they're in series is so that if the high pressure switch trips, the solenoid valve will be closed, that way no refrigerant flow, and causing a stop to the compressor.

  3. #3
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    Quote Originally Posted by EEAllen View Post
    solenoid valve opens when there's a call for cool, and high pressure switch trips when the discharge pressure is too high, the reason it they're in series is so that if the high pressure switch trips, the solenoid valve will be closed, that way no refrigerant flow, and causing a stop to the compressor.
    this happen in heating mode
    or cooling

  4. #4
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    Both, btw why does ur profile said hvac engineer?

  5. #5
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    Quote Originally Posted by EEAllen View Post
    Both, btw why does ur profile said hvac engineer?
    yes
    i am hvac engineer
    but my knowledge is not so good
    because of bad state in iraq
    and about the thread
    before i asked the question
    i thought the hi pressure switch connected in series with solenoid valve and outdoor fan
    so in heating mode
    when the pressure reach hi level the hi pressure switch will stop the outdoor fan to decrease the pressure
    and protect the compressor
    but the solenoid valve i know it work as hot gas bypass to prevent the freezing of evaporator but that happen in cooling mode
    so why they connect the hi pressure to that valve
    thank you for your help

  6. #6
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    the purpose of the solenoid valve is to just let the refrigerant flow. I have not look into the mechanical part of split ac, but they should work the same as all refrigeration systems. So if the pressure of the discharge gets too high, the high pressure switch will trip, causing the solenoid valve to close. Without the flow of refrigerant, the compressor will shutdown due to low on pressure. I wasn't able to find the mechanical side of these split AC units, if you have any, I would appreciate it if you share

  7. #7
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    kefah. Because of your extreme high ambient temps. They may be using that set up to prevent high head pressure in cooling mode. But that diagram shows the solenoid tapped off the compressor's common.
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  8. #8
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    Quote Originally Posted by beenthere View Post
    kefah. Because of your extreme high ambient temps. They may be using that set up to prevent high head pressure in cooling mode. But that diagram shows the solenoid tapped off the compressor's common.
    so the hi pressure will stop the compressor
    but the solenoid valve will prevent the freeze of evaporator or what

  9. #9
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    Quote Originally Posted by EEAllen View Post
    the purpose of the solenoid valve is to just let the refrigerant flow. I have not look into the mechanical part of split ac, but they should work the same as all refrigeration systems. So if the pressure of the discharge gets too high, the high pressure switch will trip, causing the solenoid valve to close. Without the flow of refrigerant, the compressor will shutdown due to low on pressure. I wasn't able to find the mechanical side of these split AC units, if you have any, I would appreciate it if you share
    Name:  Snap_2013.04.26_23h55m17s_001.jpg
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  10. #10
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    Quote Originally Posted by kefah View Post
    so the hi pressure will stop the compressor
    but the solenoid valve will prevent the freeze of evaporator or what
    Won't stop the compressor. It gets its power from teh compressor common wiring. but it doesn't beak the connection.

    Pic looks like a hot gas bypass.
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  11. #11
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    Quote Originally Posted by beenthere View Post
    Won't stop the compressor. It gets its power from teh compressor common wiring. but it doesn't beak the connection.

    Pic looks like a hot gas bypass.
    so when hi press switch work during hi head pressure
    it will bypass the freon to evaporator to decrease the load or what

  12. #12
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    Check the pressure witch rating.
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  13. #13
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    Quote Originally Posted by beenthere View Post
    Check the pressure witch rating.
    what you mean

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