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  1. #1
    Join Date
    Feb 2015
    Posts
    75
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    Carrier split low suction

    Having a issues with a carrier split system locking out after a week of run time on the clo. Arrived and reset system and found suction pressure running around 184/44 psig r22. 73 ambient. My suction pressure is pretty low my superheat at compressor is 20 degrees and sub cooling is at 20 as well. I have exactly a 20 degree split. 70f return and 50f supply Y1 and y2 are jumpers so unloader is always energized. I didn’t want to add charge due to my sub cooling and superheat. Charging chart showed my head pressure was correct with my liquid temp it didn’t have a suction side chart. Space cools down quickly I believe system is oversized for space. Last year both CLO boards have been replaced, Consenser fan motors replaced, and hps. Seems like this issue has been happening every summer. I ended up setting system up to run 2 stage cooling instead of loaded all the time. Suction pressure was better unloaded, around 32 degrees sat temp but still low. I’m thinking low pressure causes safety to open and lock out on clo? sending bulbs sit right next to each other on suction header wondering if txvs are fighting each other. it is a dual circuit evaporator with 2 Txvs. Looking for any help or ideas on this system.

  2. #2
    Join Date
    Feb 2015
    Posts
    75
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    Thread Starter
    Condensing unit 38aqs012
    Air handler 40rr-012

  3. #3
    Join Date
    Feb 2015
    Posts
    75
    Post Likes
    Thread Starter

    Picture of expansion valve piping

    Here is the picture of txv sensing bulbs on suction header
    Attached Images Attached Images  

  4. #4
    Join Date
    May 2018
    Location
    VA/DC
    Posts
    213
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    with a 20 sc your defiantly have charge. th 20 sh shows not enough flow. those txv are adjustable. I would turn the stems out 1 turn and see what happens. you will want to adjust each circuit individually. so take suction temp before they join. if you dont get a responce then the power heads may be faulty. but faulty power heads are usually 30+ SH




    also you need to check the txv bulbs. One looks upside down. the cap tube that goes to the power head has to be at the highest point regardless of pipe position. If you dont control the power head with vapor you will have issues.

  5. #5
    Join Date
    Dec 2004
    Location
    Chicago area
    Posts
    8,072
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    The bulbs should not be on the same line.

    How long is the t-stat run? Ive had long runs cause intermittent issues with CLO boards before.


    Sent from my iPhone using Tapatalk

  6. #6
    Join Date
    May 2018
    Location
    VA/DC
    Posts
    213
    Post Likes
    why are you guys referring to the clo. and what do you think is causing it to trip

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