Persistent Freon Leak

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Old 06-03-13, 08:28 AM
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Persistent Freon Leak

Our upstairs central AC system has a persistent Freon leak. The system was manufactured by Goodman and apparently installed by someone whose last name was not Einstein, or anything even close to it. The system is installed backwards: the access panel to the evaporator coil, the refrigerant lines, and the condensate drain outlet all face the back. The unit is snugged up against the rafters so that access to any of these items is next to impossible. Great planning.

This system is 5 years old, the same as the house. Every spring when we turn the system on it doesn’t cool adequately, so I call a service person. They come out, “find a leak”, presumably fix it, recharge the system, and we’re OK for the summer. We live in Massachusetts so our air conditioning season is mostly just June to August. Next spring the same cycle repeats. So far, the following “leaks” have been identified and addressed: leaky Schrader valve, leaky solder joint in a refrigerant line, and a loose fitting where the refrigerant line attaches to the coil.

This spring is no different than the previous. I turned on the AC, it blew cold air for a while, and then after maybe two hours it blew no air at all. So I’m assuming I’m once again low on Freon and the coil has iced over inhibiting the air flow.

It’s hard for me to believe I have more than three leaks in this system. I’m led to the conclusion that none of the service techs that have worked on this system have found the real problem. They find something but stop right there.

I’m tired of playing this game. I see I can buy an inexpensive Freon leak detector on eBay for $20 or $30. Will those things find a slow leak like I have? I was thinking of buying one of these and completely scoping out the system: take the cover off the compressor unit, take the access panel off the evaporator unit, sniff along the lines, etc. Are there certain things that tend to fail most often? I assume I need to do this when the system is operating and under pressure—correct? Obviously I can’t test the compressor when it’s running. What else can I do to track down this annoying leak?
 
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  #2  
Old 06-03-13, 08:46 AM
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Had to chime in soon as you said the unit iced up. I had mine do the same thing, turned out it was a dirty air filter. Is it possible that due to the weird install on the handler, there is a filter located somewhere that is not apparent?
 
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Old 06-03-13, 10:09 AM
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Small leak is hard to find. If you use the same AC tech every year, suggest you call a different tech, depends on where the leak is, it can be very hard to detect. detector may help, but most time not for small leaks, I prefer soap water (the old fashion way), or you can check to see if you can find oil spots which indicate leaks. If I were you, I get a big bottle of soap water, spread it all over the coil, pipes, valves, joints and see if you can find anything. good luck to you.
 
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Old 06-03-13, 07:17 PM
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Where have the leak repairs been done exactly?
 
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Old 06-03-13, 07:26 PM
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Repair Details

The repairs were as follows: Replaced internals of Schrader valve, replaced a short section of refrigerant line and straight coupling and resoldered, tightened loose nut that connects refrigerant line to evap coil assembly.
 
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Old 06-03-13, 07:35 PM
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I would suspect you have an evaporator coil leak. You would need access to it to confirm and is likely why it has nor been pinpointed yet. It may be a good time to have the evap coil replaced and installed for easier access in your attic.
 
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Old 06-03-13, 07:46 PM
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A tech can do an isolation test - pump all the refrigerant into the outdoor unit and fill the lineset and coil with nitrogen. If pressure goes down after a few days - the coil is probably leaking but it should be pinpointed.

I can't see how a lineset can leak easily unless there are lots of joints or a nail/screw was put into it.
 
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Old 06-04-13, 05:59 PM
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In order to access the coil I was thinking I could cut a fairly large access port on what would normally be the back side but in my case is the front. I would then cut a panel from sheet aluminum or galvanized steel somewhat bigger than the access port. I would apply some kind of self-stick gasket material to the cover panel and fasten the cover with a bunch of sheet metal screws all around the perimeter to make an air-tight seal. The access port could be almost the full size of the air box around the coil which would give me plenty of room to work.

If I do that, what is the best thing to locate the leak with: soap and water solution or one of those inexpensive Freon leak detectors?

If the coil turns out to be bad then it probably would make sense to put the new one in a way to provide easier access in the future.
 
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Old 06-04-13, 07:51 PM
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It is still doubtful you find the leak with out an electronic leak detector and you have to be extremely careful when installing screws into your makeshift door.
 
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