Not sure what going on here, need help!
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  1. #1
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    Not sure what going on here, need help!

    Ok here's the deal. Have a deli display case that I changed the compressor in(R-22). I tried to evacuate it and could only get down to about 2700. I'm using AK-900 and Blue Vac micron-meter. I then checked for leaks with 125psi of nitrogen and could not find any bubbles but the high side is leakin at about 1psi a minute. So I put 125 psi on both sides and left it over night. This morning the low side was still at 125 and the high side was down to 40 psi. I still cannot find a leak. Anyone got any suggestions or tips on what to do next? Thanks for any help in advance!

  2. #2
    jpsmith1cm's Avatar
    jpsmith1cm is offline Global Moderator/AOP Committee
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    Blow the nitrogen,
    squirt a bit of R-22 in,
    run the pressure up to 100-150
    Get out leak detector
    find and repair leak
    evacuate and recharge.


  3. #3
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    Does the discharge pipe run through an evaporative tray. "drain water"? Good place to look fist!
    Test with a higher pressure with a squirt of R22 in the mix.

  4. #4
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    Quote Originally Posted by barbar View Post
    Does the discharge pipe run through an evaporative tray. "drain water"? Good place to look fist!
    Test with a higher pressure with a squirt of R22 in the mix.
    There is no evaporator tray. I've tried everyones suggestions and still can't find it. I'm getting frustrated. Lol

  5. #5
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    Only so much to check, you could increase test pressure. Make sure you check compressor terminals and crankcase.

  6. #6
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    timebuilder is offline AOP Committee/Professional Member*
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    Did you spray some Big Blue on the stems of the service valves, and maybe your hose and manifold connections?
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  7. #7
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    Check the cap tube running along the suction line if equipped!

  8. #8
    jpsmith1cm's Avatar
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    Quote Originally Posted by mwright View Post
    There is no evaporator tray. I've tried everyones suggestions and still can't find it. I'm getting frustrated. Lol
    Get a better leak detector?

    Pressurize the machine and dunk it in a tub of water?

    Heck, man, a 1#/minute leak is a pretty good leak. Run the pressure up a bit higher and listen...

  9. #9
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    I stand alone on this most likely, but I find only limited value with electronic leak detectors. When I was in the service, a line went trough a bunch of spaces, and it helped narrow down the leak check down to which space the leak is in, but for finding where a leak is exactly, IMHO nothing beats soap & water. I would start by charging the nitrogen into the high side to 125 psi and starting where you brased the compressor discharge start soap & water checking the system for leaks. It has been suggested that you use the R22, and if you do, once you fill the high side, you can start the unit while you charge up the low side. To be honest, I would spray leak compound(it's just soap and water) between the fins of the condensor and check even there to find that leak. Before I report a leak is unfindable, and I have gotten to that point, I would have checked every centimeter of line and every component with the compound under system pressure.

  10. #10
    jpsmith1cm's Avatar
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    Quote Originally Posted by Bobbycold View Post
    I stand alone on this most likely, but I find only limited value with electronic leak detectors. When I was in the service, a line went trough a bunch of spaces, and it helped narrow down the leak check down to which space the leak is in, but for finding where a leak is exactly, IMHO nothing beats soap & water. I would start by charging the nitrogen into the high side to 125 psi and starting where you brased the compressor discharge start soap & water checking the system for leaks. It has been suggested that you use the R22, and if you do, once you fill the high side, you can start the unit while you charge up the low side. To be honest, I would spray leak compound(it's just soap and water) between the fins of the condensor and check even there to find that leak. Before I report a leak is unfindable, and I have gotten to that point, I would have checked every centimeter of line and every component with the compound under system pressure.
    No leak is "unfindable"

    If you have the patience and the skill, you can find it.

  11. #11
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    It is rare, but there are times when a soap & water check of every single line and component fails to show a single bubble, anywhere. Sometimes, it could be a leak to small to detect, such as an old R12 reach in that had probably leaked for years at a rate that just wasn't detectable. On occassion, I am answering a call for a machine that is needing refrigerant. I obviously go over the system completely, before making the call, but sometimes it may not have had a full charge to begin with. That happened not long ago with a rooftop package air conditioner. I don't just skim over things, on this. I meticulously search every bit of line and every component, but, sometimes the leak, even if there is one, is not detectable. If you read the specs of those electronic leak detectors you will find that each is rated on how many pounds of leak annually the detector will detect.

  12. #12
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    Quote Originally Posted by Bobbycold View Post
    It is rare, but there are times when a soap & water check of every single line and component fails to show a single bubble, anywhere. Sometimes, it could be a leak to small to detect, such as an old R12 reach in that had probably leaked for years at a rate that just wasn't detectable. On occassion, I am answering a call for a machine that is needing refrigerant. I obviously go over the system completely, before making the call, but sometimes it may not have had a full charge to begin with. That happened not long ago with a rooftop package air conditioner. I don't just skim over things, on this. I meticulously search every bit of line and every component, but, sometimes the leak, even if there is one, is not detectable. If you read the specs of those electronic leak detectors you will find that each is rated on how many pounds of leak annually the detector will detect.
    0.1 ounce per year for the detector that I trust.

    My life isn't long enough for that kind of leak to matter all that much.

  13. #13
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    Someone has never used a good H-10.

    I find it more common to have a leak too big for the bubbles to find. It can just blow them off until the the pressure drops enough.

    If I can trace it down to a fixable coil, I pull it and dunk it. Just like fixing a tire.

    jim
    Common sense isn't very common anymore.

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