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Thread: high micorns

  1. #1
    Join Date
    Mar 2012
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    8

    high micorns

    Ok guys, I will start by saying forgive me if this seems like a diy question. I have been out of the hvac field for 6 years and back in it for about 8 months. Im just trying to get back up to speed.
    I was hooking up an older rheem unit today (homeowner had some landscaping done over winter so they had it in a basment for awhile) and i put a new dryer on it and re brazed the line set. I pumped 368 lbs of nitrogen in it to check my welds and let it sit for about 4 1/2 hours while i went to check on another customer. when i got back it was still on 368 lbs of pressure, so i pumped it down to 430 microns, when i turned the pump off the microns never restabilzed and within 20 mins was back up to 1500 microns. Normally i would say there was a leak somwhere in the system. so i pumped it back up with nitrogen and checked all the welds and all around the system for leaks, never even got a small bubble. re-pumped it back down to 450 microns, and within 20 mins again it was back to 1500 and climbing. Anyone have any ideas of whats going on? All help is greatly appreciated.

  2. #2
    Join Date
    Dec 2011
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    108
    h20

  3. #3
    Join Date
    Dec 2009
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    maroon lazyboy
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    Quote Originally Posted by steveoo View Post
    h20
    that stuff..... what he said. keep on vacuuuuuuuuuuuuuuming. Good luck.

  4. #4
    Join Date
    Mar 2012
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    8
    yeah, thats kinda what microns tell you, how much moisture is in the system. Most of the time after you pump it down you kinda expect a rise right when you turn off the pump but then the microns usually stabilize around a number and don't go much higher or lower than that. this one never stabilized, but it doesn't appear to be leaking either? thanks

  5. #5
    Join Date
    Mar 2012
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    8
    wow, you guys are fast, you posted that before i could reply to the first one. Tomorrow when i get back out there ill change the oil in the pump, and let it pump for a few hours then. I appriciate it guys!! I don't remeber ever having to let it run that long before though.... I really need to stop jumping in and out of this field.. lol

  6. #6
    Join Date
    Dec 2009
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    maroon lazyboy
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    Well then.
    Just to double check, make sure you can pull a vac on your vacuum setup then. It's the little things that get us!

    Like one time the 1/4" ftg that I had hooked up to the nitrogen when press. testing... of course I valved it off for the pressure test... but then I hooked it up to the micorn gauge and it had a leak of course.

  7. #7
    Join Date
    Mar 2012
    Posts
    8
    lol, I once turned a suction line on a 410 unit into a small flame thrower... I would tell you what happened but you can probably guess... I think my vacuum pump is working fun cuase it doesn't have a problem getting 29.9, and it does drop the microns... but its a" just in case" thing... Ill let you know how it goes...

  8. #8
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    Dec 2009
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    maroon lazyboy
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    Quote Originally Posted by archie79 View Post
    Ill let you know how it goes...
    Do that! Good luck.
    Evan

  9. #9
    Join Date
    Jan 2004
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    PA
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    68,803
    Could be your hoses, or moisture, or the valves of the condenser are leaking through if you pumped the charge back into the condense instead of recovering it.

    Also, make sure the cover caps on the service valves are on tight and not leaking.
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  10. #10
    Join Date
    Nov 2006
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    Southeastern Pa
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    Make sure your hoses are new this year.
    Replaced that oil, so that's good now.
    New valve cores.
    Clean the sensor on your micron gauge. (Supco?)
    Let the pump run.

    Now, you asked "why?"

    Because the system was left open, and there is LOTS of moisture in there.

    Who removed the unit for the landscaping?
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    2 Tim 3:16-17

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  11. #11
    Join Date
    Mar 2012
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    8
    The customer removed the system himself. The system was empty when I started. I'm on site now changed oil in the vacum pump, going to turn it on and take off for a few hours

  12. #12
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    Mar 2007
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    NW AR
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    It could take all day or longer to boil the moisture out of the compressor oil.

  13. #13
    Join Date
    Mar 2007
    Location
    NW AR
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    ....and multiple pump oil changes..

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