A newbie question

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Hi, Once in a while AC unit needs refrigerant top up at the beginning of season during annual check up. Are they consumed or if there is no leak, how come it needs top up? Where does it go?
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On 5/16/2012 11:56 PM, Tony Hwang wrote:

There is a microscopic black hole in every AC compressor that sucks in Freon molecule by molecule expelling the Freon into another universe parallel to our own. ^_^
TDD
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Well, that explains a lot about freon. The parallel universe sends wasp nests, and birds nests back to our universe?
Christopher A. Young Learn more about Jesus www.lds.org .
wrote in message
There is a microscopic black hole in every AC compressor that sucks in Freon molecule by molecule expelling the Freon into another universe parallel to our own. ^_^
TDD
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Slow leak, some where. The system is under pressure, after all. Goes into the atmosphere. The sunlight breaks the chemicals into simpler chemicals, where they are absorbed by plants.
Christopher A. Young Learn more about Jesus www.lds.org .
Hi, Once in a while AC unit needs refrigerant top up at the beginning of season during annual check up. Are they consumed or if there is no leak, how come it needs top up? Where does it go?
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Stormin Mormon wrote:

So is this quite usual thing? In three years they topped up once so far. (Puron system which has higher pressure?)
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Yes, it's usual. Most systems I've worked on, need top off now and again.
Christopher A. Young Learn more about Jesus www.lds.org .
Stormin Mormon wrote:

So is this quite usual thing? In three years they topped up once so far. (Puron system which has higher pressure?)
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A/C refrigerant systems are sealed systems.... if they need topped off, then there *IS* a leak. If the system is correctly installed, and a proper 400 micron vacuum is pulled, and holds for 30minutes, you should never need to "top off" the system unless there is a leak.
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Thanks for agreeing with me.
Christopher A. Young Learn more about Jesus www.lds.org .

A/C refrigerant systems are sealed systems.... if they need topped off, then there *IS* a leak. If the system is correctly installed, and a proper 400 micron vacuum is pulled, and holds for 30minutes, you should never need to "top off" the system unless there is a leak.
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wrote:

contractors purchase nitrogen test guages of 0-250lbs. This is not enough even for an R-22 system let alone a 410A. The high side should be isolated (not always possible) and tested at 450lbs (R-22) A small piece of debris can be sucked into a hole and provide a satisfactory vacuum only to be blown back out when positive pressure is on the system. The only idea that "nature abhors a vacuum" does not apply to our situation. Should always be careful testing a unit with a high pressure guage. A low side test of 100 lbs should be enough for a satisfactory test. I've found leaks in condensors that held 100lbs but at 200 lbs began to leak.
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I pressure test R22 systems to 350psi, and R410a systems to 500psi with N2 before I pull a vacuum. Only twice in 17 years have I found any leaks in a condenser that were not caused by stupidity(dropping crap in the fan when it was running), and only once have I had a leak in a *NEW* condenser.
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wrote:

I doubt it was hit by anything. The leak was on the weld itself. I spent hours on a 450T Dunham Bush machine where 95/5 solder was used instead of silver. Over the years, we run into many interesting things manufacturers let slip by.
A pebble in a shrader valve is what used to irritate me.
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FWIW, if you have to repair any braze joints or unsweat/ resweat anything in a Rheem/RUUD condenser, the factory uses 45% silver. Silphos is not gonna do it for repairs.
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That's worth knowing. Thanks.
Christopher A. Young Learn more about Jesus www.lds.org .
FWIW, if you have to repair any braze joints or unsweat/ resweat anything in a Rheem/RUUD condenser, the factory uses 45% silver. Silphos is not gonna do it for repairs.
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On 5/18/2012 8:47 AM, snipped-for-privacy@rhosos.not wrote:

While what you say is quite true... A deep vacuum in the 15 micron range or thereabouts will usually indicate at tight system. 5 Microns is used for airborne attack radar modulators. They are cooled with liquid refrigerant that loves to leak. Most good vacuum pumps can attain 15 microns. Don't do that to automobile systems though. sucks the seals out of them.
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"PaxPerPoten" wrote in message

http://www.jbind.com/technical/faq-micron-gauges.aspx
//Some manufacturers have a micron range that they want their system pulled down to, so therefore, JB can only suggest a micron reading. Our suggestion is to pull a system down to 250-300 microns only if you are also pulling a vacuum on the compressor. Going below 250 microns, you will start degassing the oil in the compressor and it will not be the same lubricating oil as it was originally. The oil will only degass and will not suck up into the vacuum pump.\\
===================== http://www.refrigeration-engineer.com/forums/showthread.php?10919-vacuum-timeline
//This is from CPS: 2000 microns lowest average industrial requirements for A/C systems 1000 microns medium average industrial requirements for A/C systems 600 microns highest average industrial requirements for A/C systems 400 microns lowest average industrial requirements for refrigeration systems 200 microns medium average industrial requirements for refrigeration systems 100 microns highest average industrial requirements for refrigeration systems 25 microns deep vacuum for special requirements and for testing of vacuum pump efficiency\\
=================== http://www.jbind.com/pdf/Deep-Vacuum-Principles.pdf
//There are many evacuation level recommendations including the statement “evacuate the system to below 200 microns.” This should not be considered. Note we say “system” because it is possible to evacuate piping or some component other than the compressor to below this level. Refrigeration oil has a vapor pressure and by going below 200 microns, you will degas particles of the refrigeration oil. By changing the makeup of the oil, it will no longer be a true lubricating oil. Remember, hydrofluoric and hydrochloric acids, and their pal, moisture, do collect in the oil. Having nothing but time on their hands, they effectively destroy pull down and act as an abrasive on internal surfaces. If left sitting in an idle pump, these culprits keep busy by rusting and corroding internal surfaces. Deep vacuum pumps need a fill or two for every job. In order for your pump to pull a near perfect JB\\
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http://www.refrigeration-engineer.com/forums/showthread.php?10919-vacuum-timeline

Some of guys answers of pulling vacuum on systems got me interest and what got me most that you believe what manufacture tell you, well gents those that believe are fools, first of all you need to work for manufacture and go on seminars to manufacture and see for your self what is done and how is done. Vacuum should be pull down to 50 microns on any new refrigeration system. If refrigerant was already in the system refrigerants that use POE oil it may take hours are days to get down to 50 microns so it is acceptable if you can get down to 100-300 microns, However it is also necessary to have system pressurize because there are times that system may leak in one direction but not in the other. Thec. At site most determined how he/she will proceed and what he/she will need to do the job right. If system lost gas on the high side or low side it makes large difference and if system has pressure safety switches that will shut down system if refrigerant is lost. There is another phenomena how cold this system is use for we must remember that all material shrinks with low temperature and expand with high. These phenomena may cause unit to leak at one temperature but not the other, I have seen and experience these problems on my own, as some of us may say it will drive you to drink even so I don't drink. Pressure testing is necessary but one most take precaution, up to 300 PSI any system can be check, sealed units you can go up to 400 PSI. Semi hermetic unit I would not advise any one to go above 300 even so I have. By the way I never heard of 45% silver on less is on special order so that Manufacture will need to sit bare assed on fire before I would believe them!!
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On 5/21/2013 1:31 PM, Tony944 wrote:

Pressure testing and pulling a deep vacuum seem to be 2 different animals. A deep vacuum seems to insure no leaks ..Where-as many times a pressure test seems to miss them.

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On 5/18/2012 7:38 AM, Steve wrote:

I often replace the Schrader valves with the highest quality valves I can find. I've been using those having a polymer seal instead of rubber. The valves are inexpensive and I often find leaks at the service ports. Anyone who services AC/refrigeration should have the tool to replace the valves when a system is under pressure. ^_^
TDD
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Earplugs + left thumb? Hah, ha.
Yes, I've got one of those, some where.
Christopher A. Young Learn more about Jesus www.lds.org .
I often replace the Schrader valves with the highest quality valves I can find. I've been using those having a polymer seal instead of rubber. The valves are inexpensive and I often find leaks at the service ports. Anyone who services AC/refrigeration should have the tool to replace the valves when a system is under pressure. ^_^
TDD
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Core tool and replacement cores are standard equipment on my truck. With a lot of new customers, I also routinely find cores that are just plain loose so the previous "tech" has job security. Yes I tell the customer all of the things I find when I do a complete system assesment as I do for any seasonal service.
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