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  1. #14
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    That's considered a False Positive.

    Dust dirt other chemicals and yes just straight air flow can give these false readings!

  2. #15
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    For what it is worth, leak detection is part art and part science. And it can take awhile to get good at it. There are a few factors that come into play. That being said . . .

    There are many facets to our trade, many trades combined into one trade. Not all of the younger techs coming up in the HVAC/R trade today have had, or do have, a well experienced mentor. Or employer who is looking for their techs to excel. Combine that with the techs who don't have a highly motivated drive to become the best there is.

    Where I work, we have techs from the entry level on up. It's often a difficult balancing act.

    I started doing this almost 40 years ago, and one reason I come on this forum it to keep up with the trade and pick up pointers. I'm pretty darn good at what I do, near the end of my career, and still learning stuff and various tips.


    Quote Originally Posted by jas001 View Post
    Right, that makes sense now. But the fact that it went off at all while the unit was on does indicate it's detecting refrigerant, correct? Guy #2 stated that air simply blowing on the device would make it go off, which didn't seem right to me. I think there is refrigerant leaking in the unit, but neither tech precisely located it yet. I guess I expect 100% competence with these guys (or close to it), but it seems neither guy was.
    I do a triple evac with nitro to remove non condensables.

  3. #16
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    Quote Originally Posted by pecmsg View Post
    That's considered a False Positive.

    Dust dirt other chemicals and yes just straight air flow can give these false readings!
    Ah, ok - thank you for that clarification. So maybe there really isn't a persistent leak (now, at least), and perhaps it was just a loose valve that had since been tightened.

  4. #17
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    Quote Originally Posted by BBeerme View Post
    For what it is worth, leak detection is part art and part science. And it can take awhile to get good at it. There are a few factors that come into play. That being said . . .

    There are many facets to our trade, many trades combined into one trade. Not all of the younger techs coming up in the HVAC/R trade today have had, or do have, a well experienced mentor. Or employer who is looking for their techs to excel. Combine that with the techs who don't have a highly motivated drive to become the best there is.

    Where I work, we have techs from the entry level on up. It's often a difficult balancing act.

    I started doing this almost 40 years ago, and one reason I come on this forum it to keep up with the trade and pick up pointers. I'm pretty darn good at what I do, near the end of my career, and still learning stuff and various tips.
    Thanks for that perspective. I guess I shouldn't say I expect near perfect competence, but I guess a combination of competence and honesty. It's hard to know when that's happening as a layman, so I really appreciate the feedback I'm getting here.

  5. #18
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    If legitimately refrigerant had to be added then yes there is a leak. Refrigerant is circulated not consumed. Unfortunately your system is not like a car tire that can be removed and submersed in water to find even a pin hole. There are literally 10's of thousands of Brazed or Soldered connections that can develop leaks as well as well as how many ft or miles of straight copper. Again any ware is suspect.

  6. #19
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    If the system is 4 lb low there has to be a leak somewhere. I have to assume that the system was fully charged when the coil was replaced so about 1/3 of the charge in a year + is a lot. If the service ports were leaking one of the 2 techs should have picked it up. Depending on temperature the system may not have had enough pressure to do a good leak test which may be why the supervisor asked about N2.

    Generally with the electronic you can get false positives but if you go over the same area multiple times and get a reading every time there is a good chance something is there. Yes wind can affect a leak detector which is why you hit the spots you pick up something several times. If wind is causing a false positive it will not be blowing the same every time you make a pass.

    I have seen compressors leak but very few and most have been catastrophic (terminal blow out) where there is no question. I have also seen Rev. valves leak in locations that are not repairable but again not often.

    At this point I can not fault either tech with technique but fault them both for effort as it doesn't seem like either did enough to verify their diagnosis. You have a leak somewhere and at the size it should not be hard to find. It may come down to pulling the remaining charge and do a pressure test with N2+ refrigerant and component isolation. They should be able to pump the refrigerant into a clean drum and put it back when done to minimize cost if it turns out to be a repairable leak. If the system needs changed the refrigerant needs to come out anyway.

  7. #20
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    Quote Originally Posted by BNME8EZ View Post
    If the system is 4 lb low there has to be a leak somewhere. I have to assume that the system was fully charged when the coil was replaced so about 1/3 of the charge in a year + is a lot. If the service ports were leaking one of the 2 techs should have picked it up. Depending on temperature the system may not have had enough pressure to do a good leak test which may be why the supervisor asked about N2.

    Generally with the electronic you can get false positives but if you go over the same area multiple times and get a reading every time there is a good chance something is there. Yes wind can affect a leak detector which is why you hit the spots you pick up something several times. If wind is causing a false positive it will not be blowing the same every time you make a pass.

    I have seen compressors leak but very few and most have been catastrophic (terminal blow out) where there is no question. I have also seen Rev. valves leak in locations that are not repairable but again not often.

    At this point I can not fault either tech with technique but fault them both for effort as it doesn't seem like either did enough to verify their diagnosis. You have a leak somewhere and at the size it should not be hard to find. It may come down to pulling the remaining charge and do a pressure test with N2+ refrigerant and component isolation. They should be able to pump the refrigerant into a clean drum and put it back when done to minimize cost if it turns out to be a repairable leak. If the system needs changed the refrigerant needs to come out anyway.
    Thanks for the feedback. I called company #2 and spoke with a service manager. They are sending a more "senior" technician out next Tuesday. The manager basically said what you (and others) said: there's a leak and we need to find it and address it. Sounds like they are going to do the nitrogen test and go from there. Will post an update afterwards.

    Thanks again for all the responses. Gave me a little more confidence to have that conversation with the manager and some peace of mind I'm going the correct route.

  8. #21
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    [QUOTE=jas001;25850105]Thanks for the feedback. I called company #2 and spoke with a service manager. They are sending a more "senior" technician out next Tuesday. The manager basically said what you (and others) said: there's a leak and we need to find it and address it. Sounds like they are going to do the nitrogen test and go from there. Will post an update afterwards.

    If they find a leak ( using a electronic leak detector ) , have them identify afterwards with soap and show you! as in post #4. If the soap is a creamy foam then the leak is tiny, if it’s bubbling even a little your leak is more pronounced. I would not accept a leak prognosis without a soap suds and visual.

    No running of equipment to disturb air movement as already mentioned, couple of the 1st places I would have them check is the bottom of the accumulator, if it goes off with a electronic, then I would have them smash that area with a punch of soap as it’s hard to get to it with soap as it’s butted so close to the frame for a visual.

    Other area would be the service valve access cap ( where they unscrew the cap to front seat the valve ) and the Schrader cap ( where they hook up the gauges ) other area are by the metering device. Especially if there are threaded screw in connections, and especially if there are any field install screw in TXV.

    Have them compare what the recovered charge is compared to the outdoor unit data plate factory charge says. They should know how much to add to the factory charge if your lineset is over a certain run to get a close factory charge to compare to. When all is said and done ( leak finding and repairs are made ) new drier is a good thing, if outdoor temperature is below what the manufacturer says for subcooling charge have them weight in charge, until a warm day where they can check and adjust charge to manufacturers spec. in cool mode. Heat Pumps are what they call critically charged system, you need to dial in the charge as closely as possible....At least that’s what they told me in Tech. School some 45 years ago...
    Last edited by Bazooka Joey; 04-03-2020 at 05:36 PM.

  9. #22
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    [QUOTE=Bazooka Joey;25850114]
    Quote Originally Posted by jas001 View Post
    Thanks for the feedback. I called company #2 and spoke with a service manager. They are sending a more "senior" technician out next Tuesday. The manager basically said what you (and others) said: there's a leak and we need to find it and address it. Sounds like they are going to do the nitrogen test and go from there. Will post an update afterwards.

    If they find a leak ( using a electronic leak detector ) , have them identify afterwards with soap and show you! as in post #4. If the soap is a creamy foam then the leak is tiny, if its bubbling even a little your leak is more pronounced. I would not accept a leak prognosis without a soap suds and visual.

    No running of equipment to disturb air movement as already mentioned, couple of the 1st places I would have them check is the bottom of the accumulator, if it goes off with a electronic, then I would have them smash that area with a punch of soap as its hard to get to it with soap as its butted so close to the frame for a visual.

    Other area would be the service valve access cap ( where they unscrew the cap to front seat the valve ) and the Schrader cap ( where they hook up the gauges ) other area are by the metering device. Especially if there are threaded screw in connections, and especially if there are any field install screw in TXV.

    Have them compare what the recovered charge is compared to the outdoor unit data plate factory charge says. They should know how much to add to the factory charge if your lineset is over a certain run to get a close factory charge to compare to. When all is said and done ( leak finding and repairs are made ) new drier is a good thing, if outdoor temperature is below what the manufacturer says for subcooling charge have them weight in charge, until a warm day where they can check and adjust charge to manufacturers spec. in cool mode. Heat Pumps are what they call critically charged system, you need to dial in the charge as closely as possible....At least thats what they told me in Tech. School some 45 years ago...
    Oh, I'll be watching them like a hawk. Thank you for the feedback - I will keep it all in mind.

  10. #23
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    Just a quick update. Company #2 (ARS, btw) came back with a new tech, pumped the system full of nitro (500 psi) and found the leak (says it was on the "high switch", I think?). Since the unit was still under the parts and labor warranty, no charge for finding and fixing the leak, but I had to pay to refill the entire unit with refrigerant. He said he couldn't refill with the old refrigerant since it could be dirty, which sounded a little fishy to me. The leak did look to be close to where the first company said there was a small leak - but I'm fairly certain there is no leak on the compressor. They guaranteed that this was the only leak. So in the end, I'm satisfied with the solution and should have a working system for at least a few more years.

    On a separate note.... this is the second time they tried to sell me on the whole UV light/Air Scrubber deal. He showed me a little bit of mold in the duct work. Probably a subject for a different thread, but are those things worth the cost?

  11. #24
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    On your last note, I see a little bit of mold everywhere I go. You should see the window my sweetie pointed out to me yesterday. I couldn't believe how bad it was. Like a three day or more project. Been spending all morning on it today. It's the spare bedroom, which she gets. I get the garage.

    On your other note, regarding bad refrigerant, unlikely. They were probably just trying to cover some expenses. And on a personal note, I keep this one recovery bottle on my truck just for that purpose, to re-use the customers refrigerant.

    Other companies / techs will fill a bottle with mixed refrigerants, and that would not be suitable for re-use.


    Quote Originally Posted by jas001 View Post
    Just a quick update. Company #2 (ARS, btw) came back with a new tech, pumped the system full of nitro (500 psi) and found the leak (says it was on the "high switch", I think?). Since the unit was still under the parts and labor warranty, no charge for finding and fixing the leak, but I had to pay to refill the entire unit with refrigerant. He said he couldn't refill with the old refrigerant since it could be dirty, which sounded a little fishy to me. The leak did look to be close to where the first company said there was a small leak - but I'm fairly certain there is no leak on the compressor. They guaranteed that this was the only leak. So in the end, I'm satisfied with the solution and should have a working system for at least a few more years.

    On a separate note.... this is the second time they tried to sell me on the whole UV light/Air Scrubber deal. He showed me a little bit of mold in the duct work. Probably a subject for a different thread, but are those things worth the cost?
    I do a triple evac with nitro to remove non condensables.

  12. #25
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    “and found the leak (says it was on the "high switch", I think?) “

    Prooobbably he was referring to the high pressure ( refrigerant ) control? Hopefully he replaced it with another one of similar Refrigerant Pressure opening/closing ratings or a OEM to your unit, if it was a HPC ( High Pressure Control ) and not just removed it.

  13. #26
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    Quote Originally Posted by Bazooka Joey View Post
    “and found the leak (says it was on the "high switch", I think?) “

    Prooobbably he was referring to the high pressure ( refrigerant ) control? Hopefully he replaced it with another one of similar Refrigerant Pressure opening/closing ratings or a OEM to your unit, if it was a HPC ( High Pressure Control ) and not just removed it.
    Yep that's it - the high pressure switch. They were able to repair it. He said it was a very small leak, since they had to pump it to 500 psi to find it.

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