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  1. #1
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    Feb 2019
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    unstable pressures

    Suction Pressure: 107-117
    SLT: 61
    VSAT: 35-39
    SH: 26-21
    Head Pressure: 305-312
    LLT: 88
    LSAT: 96-99
    SC: 8-9
    ODA: 85

    So I came to this unit and the compressor was making a nasty noise. The unit right next to it(same exact unit, only 1 ton larger) was quite as a mouse, just a slight hum to let you know it was running. My pressures were all over the place and originally my SC was at 16* upto 19* and the unit calls for 9* SC. I took it as the unit was full of non-condensables and that it was overcharged by the last technician who was out, because after talking with the h/o, they mentioned that the tech stated that the unit was undercharged and added refrigerant. He may have brought in the non-condensables into the system at that time. I pulled the recovery machine and tank from the van, along with a scale. I don't have an extra hose yet, only a larger one for pulling a vacuum, so I removed my suction line hose and used that because I needed the liquid line hooked up to read my SC. As I removed my suction line hose, my hand got saturated in oil, not just a little bit of oil, but full saturation from the suction port. So now I'm wondering if the evaporator is oil logged??? I understand that could happen from an overcharged system, or is there any other way it could happen with this much oil. So, what I want to do is evacuate the system, pull a vacuum, and put virgin refrigerant into the system and start from scratch. I was going to do this from the beginning, but the system was factory charged with 9lbs 13oz and I was shy that from what I had left in my r410a tank. So I didn't want to do this if I couldn't properly charge the system back up. Now my question is, am I approaching this correctly or should I be looking for something else?

  2. #2
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    Jan 2004
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    While your at it, replace the existing LLFD. It could be restrictive and caused it to look like the system was low on charge when the other tech was there.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

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  4. #3
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    Mar 2015
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    Medford, N.Y.
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    I think that I thought that I read somewhere about a "test" that you could do to determine if there is/was NCG in the system.Before all of that "repair work" is accomplished,maybe

  5. #4
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    Now my next next question is after doing all of this, because I have this job lined up in my schedule for tomorrow. After evacuating and pulling a vacuum, the oil that I'm finding in the suction line is obviously migrating from the compressor correct? Now when pulling that oil out with the vacuum, wouldn't my compressor be hurting with that oil missing? How would I be able to, if at all, prevent that from happening?

  6. #5
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    Aug 2002
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    Southold, NY
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    Oil migrates with the refrigerant All the Time!

    Don't worry about a few oz's!

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  8. #6
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    Thread Starter
    Quote Originally Posted by pecmsg View Post
    Oil migrates with the refrigerant All the Time!

    Don't worry about a few oz's!
    I only ask because it seemed like a lot, more than usual but definitely not like a cup(8 oz) of oil or anything crazy, but a good puddle sitting in my hand after removing my suction line. Maybe like a good tablespoons worth.

  9. #7
    Join Date
    Dec 2014
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    Whys the comp making a nasty noise?
    What's the amp draw and RLA?
    Head is low for 85 ...unless it's a high seer unit?
    Suction is lowish too tho.

    What are the indoor conditions?

    Has the comp been previously changed? If that's the case, might be extra oil in the system, causing the compressor some problems.

    Sent from my SM-G950U using Tapatalk

  10. #8
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    Mar 2015
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    I think that somehow NCG got into the system, I think that I had better remove those damn NCG and now no good freon, I think the customer now owes me $5 bananas for doing a good job,BUT WAIT,hang on a second or two here, I think I have the same readings as I did before .I think the customer still owes me $5 bananas,anyways.

  11. #9
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    Feb 2019
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    Quote Originally Posted by icy78 View Post
    Whys the comp making a nasty noise?
    What's the amp draw and RLA?
    Head is low for 85 ...unless it's a high seer unit?
    Suction is lowish too tho.

    What are the indoor conditions?

    Has the comp been previously changed? If that's the case, might be extra oil in the system, causing the compressor some problems.

    Sent from my SM-G950U using Tapatalk
    I don't know why the compressor is making a nasty noise, it just sounds really loud compared to its twin brother right next to it. Amp draw was low at I believe 5.some amps and RLA was 21amps. Yes, it's a higher seer unit, 17 seer to be exact, the unit itself is only 2 years old. Indoor DB was 75 at the return with 58 at the supply. No, the compressor hasn't been changed out, but has had charge added to the system. And shortly after is when the noise started.

  12. #10
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    Quote Originally Posted by TechmanTerry View Post
    I think that somehow NCG got into the system, I think that I had better remove those damn NCG and now no good freon, I think the customer now owes me $5 bananas for doing a good job,BUT WAIT,hang on a second or two here, I think I have the same readings as I did before .I think the customer still owes me $5 bananas,anyways.
    With the pressures fluctuating the way they are, non-condensables are at the top of my list of culprits. But if I'm not mistaken, I believe you can disconnect the compressor from the system and run only the condenser fan motor for about 15 minutes and the refrigerant in the condenser should be at ambient temperature and then the pressure should be the same as the p/t chart for that temperature. And if it doesn't then that confirms non-condensables.

  13. #11
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    If I'm approaching this wrong Terry, speak up, let me know. That's why I posted on here to get some insight. My crew is not the greatest when it comes to getting answers, sometimes it'll take hours or even days to get a response. And even sometimes not at all. So I'm pretty much left to myself on things and so I look to the best resources I have at my disposal.

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