With a big leak, yes - but I've found many "seepers" that read perfect when running. Leaks so small the old halide torch couldn't find them and electronic leak detectors have a hard time, but when you open up the heater box and expose the evaporator, the bottom corner is covered with oily dirt. Clean it up and squirt some soapy water on it, and you have bubbles. 1 pound a year leaks- sometimes half a pound - but leaks
And, eventually, the low side will read zero while the compressor is running. Except that car AC have a low side pressure switch.
OK I don't like to argue on the internet, but I agree with the others.
When the system is off, the pressure is equal and will leak the same high side or low side. When the system is turned on of course the pressure will be low because the charge is Low but the leak itself will not effect the pressure if it is small so there will be no difference if the leak was on the high side or low side.
thanks for listening, I'm done here.
Mark
leak the same high side or low side.
be low because the charge is Low but the leak itself will not effect the pressure if it is small so there will be no difference if the leak was on the high side or low side.
The question at hand: A low side leak (house central AC), produces zero PSI on the low side while the system is running. A high side leak (house central AC) can result in less than zero PSI on the low side while the system is running. I have found this to be the case. And, it's still permissible to ask me why this is.
agree with the others.
will leak the same high side or low side.
will be low because the charge is Low but the leak itself will not effect the pressure if it is small so there will be no difference if the leak was on the high side or low side.
Here is a chance for me to learn from you. So, tell me why (as with others) you believe that a low side leak of a central AC system on a house would not result in zero PSI on the low side while the system is running? I may very possibly be mistaken, and here is my chance to learn.
Stormy, you're correct! If the system refrigerant is low, the low side pressure could easily drop to atmospheric pressure when the compressor turns on.
You have to remember that there are some numbnutz here that think that a center-tap transformer can convert single phase into 2-phase, all because they got their oscilloscope leads mixed up..
But that will happen even if the refrigerant leak was a slow leak on the high side. An OPEN low side will give a 0psi reading, obviously. As woll a grosly undercharged system. If you recharge a system with a slow low side leak, you will NOT get a zero reading.
OK, we're talking about a system that has a very small leak. His point is that when the system is off, refrigerant is going to leak out essentially equally whether the leak is on the high side or the low side, because the system pressure is equal when it's off. You agree?
Now, you come back a week later like you did and it's lost a pound of refrigerant. By what physics does that produce zero pounds of pressure on the low side, if and only if the leak is on the low side? It would seem to me that the pressure is going to be independent of where the leak is, because the leak is small and has no observable differing effect on the system pressure, whether it's on the high or low side. The system just has less refrigerant and that affects the pressures, but without regard to where the leak is. The only way it could effect pressure to make an observable difference that I can see would be if it was a large leak, not a small one. And you're not saying just observable, you're saying a small leak produces 0 psi?
Something here we're missing?
But that isn't what Stormin is claiming. He's claiming that a low side pressure of zero while it's running means that the small leak is on the
*low side*.
And obviously you couldn't understand that thread either, because I provided plenty of cites including the IEEE and electrical eqpt manufacturers that fully agreed with my position. Just as ignorant about electricity as HVAC. Good grief.
low, the low side pressure could easily drop to atmospheric pressure when the compressor turns on.
that think that a center-tap transformer can convert single phase into 2-phase, all because they got their oscilloscope leads mixed up..
If the leak is on the high side, then a running system will show below zero on the low side.
Thank you. Nice to get something right, once in a while.
CY: Systems leak out, at leaks. So, the turned off system leaks... at the leaks. Disagree.
CY: If the leak is on the high side, eventually the system will get down to the point where the low side (running) reads below zero.
CY: Makes a big differnce, to me.
The system just has less
CY: I think it makes a difference.
The only way it could effect pressure to make an
CY: Small leak will behave same as big leak, just takes longer to get to that point.
And you're not saying just observable, you're saying
CY: A small leak on the low side will eventually result in 0 PSI on the low side while running.
CY: Must be!
. Christopher A. Young Learn about Jesus
More to the point, I stated that on the HO system I looked at, the low side (running) was below atmospheric so it was a high side leak.
The reverse is usually true.
Of course it leaks at the "leaks". The question was do you agree that with the system off, when it hasn't been running for hours, that the pressure in the system equalizes and it's the same on the high and low side? Apparently your answer is "no"? Must be some strange physics.
And why won't exactly the same thing happen if the small leak is on the low pressure side? Explain. The low pressure reading when it's running goes down because of the loss of refrigerant, without regard to which side the leak is on. That is all that Claire, Mark and I are saying.
But you haven't been able to explain why there would be any difference. Again, must be some strange physics.
Then explain how. By our laws of physics and how the system works, we can't see how there could be a difference with a small leak.
Not really true, plus I thought you were talking about taking readings over a few minutes, where a small leak doesn't have the time to leak any amount of refrigerant that would make a difference.
Define "eventually". We're not talking about a week, which is the timeframe of the leak you're talking about making a difference.
The only thing I see missing is any explanation to the alleged effect.
And eventually everyone on this newsgroup MIGHTagree with Stormy. The point is, when you are doing a test on a functioning system you can NOT assume there is no leak on the low side because you do not get a zero reading on the low side, and you cannot assume the high side is tight just because you do not get a below zero reading on the low side. I've worked on numerous systems that definitely had leaks, because they had been recharged several times over the last year, that had perfectly acceptable pressures when I tested them. At some point in the future, when the freon had all leaked out, there would come a time when the low side read zero, and even below - but I would not depend on those readings to tell me where the leak was, knowing it was one of those nasty hard-to-find "seepers".that even an utrasonic leak detector can't reliably detect. You just put in dye and run it for a while then lookk for the glow, or look for oily spots where oil should not be (the most reliable indicator of a leak in many cases)
In a virtually empty system, if forced to run, the low side will ALWAYS be below zero - even if it is a tight system (with no leaks)
CY: Did anyone say that till now?
and you cannot assume the high side is
CY: Did anyone say taht?
CY: I'd expect that, soon after the recharge.
At some point in
CY: I'd also not depend on that to locate the leak. Don't think I ever have.
In a leaky system, with low side leak, the low gage will read zero while the system is running.
ONLY if it has a big enough leak. a "seeper" won't show.
Maybe not exactly that, but you did say that the pressure on the low side can be used to determine whether a small leak is on the high or low side. That is the point of disagreement.
Stormin: "Saturday June 7, I went out and put the gages on. The low side was six inches mercury below atmospheric. This means the refrigerant leaked out, and it's a high pressure side leak."
Mark: "even if it was a very slow leak?"
Stormin: "Yes, even if. " "I've found low side leaks end up being zero, low side, while the compressor is running."
Clare, Mark and I obviously agree that whether a small leak is on the high pressure side or the low pressure side, it will result in the same readings while the system is running. Over days or weeks, some of the refrigerant leaks out. It leaks out whether the leak is on the high side or the low side, because with the system off, the pressure is equal. When the system is running, sure, the fact that it has less refrigerant effects the pressure readings. But the tiny leak has no different observable effect on those readings whether the leak is on the high or low side. You can't tell from the pressure reading on the low side whether the small leak is on the high side or the low side. That is what you claimed. If it's possible, then just explain the physics.
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