Refrigerant Leak Detection

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Old 06-20-14, 06:48 AM
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Refrigerant Leak Detection

One of our two Goodman central AC systems has a slow refrigerant leak. Three times HVAC "professionals" have "repaired" the system but each following year the system is back to a marginal cooling condition. They do some diagnostics, find a problem (supposedly), fix that problem, and refill the system. Things are good for the remainder of that season but then the next year we repeat that cycle.

Since the pros haven't found the root cause of the problem I thought I'd take a crack at it. I asked the HVAC company if I could borrow their refrigerant sniffer. They said no. I see you can buy sniffers on eBay for $25 or so. I'm wondering if they'd likely be adequate for a slow leak. What kind of sniffer should I be looking for? Do I need to have the AC compressor running the whole time I'm looking for a leak? That's not a problem except for when I'm sniffing near the compressor unit.

Some additional info. We live in Massachusetts near the ocean so our AC season is not all that long. Problems found and supposedly fixed: loose fitting at evaporator unit, leaky Schraeder service valve, leaky suction line (section of line replaced). Unit is a Goodman CRT36-1A. System is about 7 years old. Any help much appreciated.
 
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Old 06-20-14, 04:05 PM
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Don't waste your money on a $25 detector.
 
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Old 06-20-14, 06:34 PM
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I don't even trust the $200 range.
$415 will get you a good Inficon Dtek Select.
 
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Old 06-21-14, 03:32 AM
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On my system , I would replace both Schrader valves ( high and low pressure service valves / fitting ) as SOP . Once you buy the device to change them out without discharging the system , a cheap repair / preventative maintenance . Be sure to coat them with the appropiate refrigeration oil or Nylog .

Same with automotive A/C systems .

Next , I would inject some florescent dye into the system & try a UV light , at night or in the dark ( for inside components ) .

Same with automotive A/C systems .

God bless
Wyr
 
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Old 06-23-14, 05:41 AM
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Hey Mister Twister,

I happen to have a battery operated UV LED light I used to track down some oil leaks on my car engine. It's small and portable and seems like it would be great for what you suggest.

How do I go about injecting the UV dye into my AC system? Do I need some special tool to do that? After I inject the dye I assume I'd run the system for a while and then start the Easter egg hunt. I assume this dye is a liquid. Do I need to catch it when its actively leaking (when the compressor is running) or can I look for it anytime? If it evaporates does it leave a fluoresecent residue?
 
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Old 06-24-14, 03:00 AM
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I use the UV dye method for automotive A/C . Others are probably mor familiar with the best method to inject the dye into a home A/C system ?

On a car , I run the A/C for a day or two & then check for leaks . The engine does not need to be running . Probably safer if it is not .

The little kit I bought has some plastic " glasses " that look like safety glasses , that look silly but do help . I try to do my investigating at night . Shine the UV light at every nook and cranny that the system could possibly leak from .

First place U would look / check is the Schrader valves on the service valves . You may need to " wash " them to remove any dye left from when you introduced it into the system ?

I would look at any " mechanical " connections / joints , first . Then those that are brazed .

Do not forget the A-Coil and the metering device near the A-Coil .

God bless
Wyr
 
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Old 06-24-14, 05:30 AM
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One very simple, effective, low tech., low cost method of leak detection has not been mentioned. -Bubbles-
I have an expensive refrigerant sniffer that I go to first but there are times I will use spray or bottle bubbles that are specifically made and sold for the purpose. In a heavy wind when checking outside, or when my batteries die, it's bubbles. For very small leaks you may have to apply then wait a few minutes for indication. Obviously they are useless on a system completely uncharged, but so is a sniffer or dye. They can still be used on evap/condenser coils, but it can be difficult in the actual finned area.
 
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Old 06-25-14, 01:51 PM
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Do not add die to your system! It will kill it plus tech's will hate you for it.
 
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Old 06-26-14, 03:37 AM
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I have heard Super Seal will kill a system . Have not heard that about dye ?

God bless
Wyr
 
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Old 06-26-14, 07:43 AM
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Soap bubbles is the way to go for me. I've found most of my leaks that way
 
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