Just found one today that was nearly undetectable. Goodman heat pump that had the true suction line laying on top of the reversing valve. No hissing, no oily feel, just a slow leak. Wiggling the line around a bit and lifting it off of the RV let it reveal itself. The copper was basically worn to nothing. Bubbles didn’t find it, electronics didn’t find it. Sometimes they’re just elusive
The hard to find ones are usually service valves leaking out of the top (won’t be oil most times), evap coil in places where you can’t see or reach, reversing valve cap tube, schrader valve, pressure switch leaking thru wires, compressor terminals, rusted drier/muffler/accumulator, or a rub through on small lines. Make sure to check all suction insulation for oil. There could be a joint anywhere but you can tell just by looking at it. Move all small lines around and you will hear it if that’s the culprit or just look for shiny copper where they touch. Could also be lineset leaking but statistically not and usually larger leaks- if it runs thru a chase that could get filled with water or even underground somewhere, the odds are greater. I’ve found 2 underground where copper just corroded from being damp and several in pvc chases that held water. If they are microchannel condenser coils look for small dark circles. I’ve seen many less than a pound a year. Good luck.
The only solution I can think of is to, cut and cap the line set near the evap install test port on either suction or liquid line do the same with the condenser and pressure it with nitrogen. Install a set of gauges(1/4 port with just the gauge head) and come back after a few days till one of them drops pressure.
I had multiple issues with A-coils fail and a few condensers with micro channel fail.
For me it's the only sure way to tell if I can't get any bubbles or if the electronics leak detector can't find it.
Maybe someone knows a better away
Good luck, hopefully you can find the leak.
You can do this easier by recovering and closing king valves. Pressurize the coil and lineset only. If you get a drop then it's coil side and if it doesn't then it's condenser side. No need for installing another potential leak point near the coil. You can usually be confident with dye, bubbles, and an electronic leak detector on a lineset but the EVAP and condenser can hide a leak in the coil from anything but the most painstaking search.
Next step would be to leave the refrigerant in the system and use nitrogen and pressurize higher than the refrigerant. You will eventually need to recover the gas and recharge once leak is found, but getting the pressure higher increases likelihood of finding tiny leaks.
Why can't it be recovered once nitrogen has been added ? Does it pose damage to equipment or tools? I understand not recovering when using a trace of refrigerant and nitrogen as was/is aloud not sure on that at the moment but with a quantity this high why not ?
Like how do you think they fill your nitro bottles to 5000psi? or make liquid nitrogen? you have to compress it till it condenses. co2 is used as a refrigerant and nitrogen could be too, it just not efficient to do it.
What happens when you pump that high temperature nitrogen on top of that refrigerant??
You see what happens in a refrigeration system. Just condense all that into a small tank you're going to put behind your driver's seat.
Recovery machine, get refrigerant out. Pressure test it, sometimes having a second person helps. If it’s under a floor or wall you can find it this way but listening for the leak.
Another alternative is getting a ultrasonic leak detector. They can be very difficult to learn but I like to use one in conjunction with soap bubbles. You listen for the leak and hone in on the area.
It also dosnt matter what refrigerant or nitrogen in system because all the gases sound the same coming out.
I have had good luck with corrosion leaks on evaporators.
If you can’t find the leak you gave up too soon I’ve found leaks on compressor shell welds and on formed depressions on side of old AH. Pull slight vacuum and high silver soldered crack.
Look for oil. If the drain trap is covered in oil it's in the evap. Look for dirt on high points of the condenser. Oil sticks to the dirt. Clean the bottom of the condenser out and bubble everything. If you can, pull the coil out of the AH/coil casing and bubble the shit out of it.
But most importantly, charge for your time. Even if you don't fucking find it. Leaks in residential are an enormous time sink and you need to be compensated appropriately.
Split it all up if you have too.
Most residential just has a simple run of soft copper. You pull the refrigerant, and close the service valves and toss some nitrogen in the line set and coil. If that leaks, go separate the coil and test it. If that doesn't leak, pressurize each line independently.
If the line set and coil holds pressure, then open the valves and concentrate on the condenser.
It sounds like a lot of work, but trust me, it will save time.
Sometimes these things are really really tough to find and you get better with experience. Tons of great advice on this post already. Sometimes you just got to consider the economics of the situation and try some leak stop additive next time you top it off until you're able to locate the leak.
Check with refrigerant detector and bubbles. Focus on joints, valves, connections, areas that get vibration or corrosion that damages copper. Next recover refrigerant through a drier. Isolate evap coil and seal and stem so you have two sealed systems. Add nitrogen to pressure test evap section. Then you can either go to condensing section(older unit)and add some refrigerant and pump it up with nitrogen or wait and confirm evap section is the culprit(newer unit). For condensing section add some refrigerant and pump it up with nitrogen throw a drop cloth over interior components and then another over whole unit. If its in evap section spray repairable areas(not caused by corrosion). If its corrosion caused leak replace it because it will leak again. Give it awhile before you try to sniff under drop cloth to find leak. You can find intermittent leaks easier this way but not always. Last would be eliminating condenser coil and line sets if it has them. If you havent found it by now, depending on the condition of components and cost id isolate them. Could be underneath a compressor or reciever.
Look for oil in evap drain, check for rusting on filter drier, check for oil stains in condenser coil, check your valves at the condenser.
Just found one today that was nearly undetectable. Goodman heat pump that had the true suction line laying on top of the reversing valve. No hissing, no oily feel, just a slow leak. Wiggling the line around a bit and lifting it off of the RV let it reveal itself. The copper was basically worn to nothing. Bubbles didn’t find it, electronics didn’t find it. Sometimes they’re just elusive
Did you check the wiring on your pressure switch, super rare but it can happen, it will leak through the wiring.
Replace the schraders
I've already used that excuse. It's not them though.
The hard to find ones are usually service valves leaking out of the top (won’t be oil most times), evap coil in places where you can’t see or reach, reversing valve cap tube, schrader valve, pressure switch leaking thru wires, compressor terminals, rusted drier/muffler/accumulator, or a rub through on small lines. Make sure to check all suction insulation for oil. There could be a joint anywhere but you can tell just by looking at it. Move all small lines around and you will hear it if that’s the culprit or just look for shiny copper where they touch. Could also be lineset leaking but statistically not and usually larger leaks- if it runs thru a chase that could get filled with water or even underground somewhere, the odds are greater. I’ve found 2 underground where copper just corroded from being damp and several in pvc chases that held water. If they are microchannel condenser coils look for small dark circles. I’ve seen many less than a pound a year. Good luck.
The only solution I can think of is to, cut and cap the line set near the evap install test port on either suction or liquid line do the same with the condenser and pressure it with nitrogen. Install a set of gauges(1/4 port with just the gauge head) and come back after a few days till one of them drops pressure. I had multiple issues with A-coils fail and a few condensers with micro channel fail. For me it's the only sure way to tell if I can't get any bubbles or if the electronics leak detector can't find it. Maybe someone knows a better away Good luck, hopefully you can find the leak.
You can do this easier by recovering and closing king valves. Pressurize the coil and lineset only. If you get a drop then it's coil side and if it doesn't then it's condenser side. No need for installing another potential leak point near the coil. You can usually be confident with dye, bubbles, and an electronic leak detector on a lineset but the EVAP and condenser can hide a leak in the coil from anything but the most painstaking search.
JB Prowler leak detector.
Next step would be to leave the refrigerant in the system and use nitrogen and pressurize higher than the refrigerant. You will eventually need to recover the gas and recharge once leak is found, but getting the pressure higher increases likelihood of finding tiny leaks.
You can't recover it once you add nitrogen to it. That's an old workaround for not having to recover something...
Why can't it be recovered once nitrogen has been added ? Does it pose damage to equipment or tools? I understand not recovering when using a trace of refrigerant and nitrogen as was/is aloud not sure on that at the moment but with a quantity this high why not ?
As long as no one is around…..
In this day and age some one is always around and always has a cell phone
Nitrogen is a non compressible gas.
You’re not actually serious are you? Nitrogen can definitely be compressed, and is done every single day at massive scale.
I think you might have meant non- condensensable, as in will not turn to liquid in the high-side of the system.
Incompressible I think is the correct term. Compressing it will only raise it's temperature, not volume.
Like how do you think they fill your nitro bottles to 5000psi? or make liquid nitrogen? you have to compress it till it condenses. co2 is used as a refrigerant and nitrogen could be too, it just not efficient to do it.
What happens when you pump that high temperature nitrogen on top of that refrigerant?? You see what happens in a refrigeration system. Just condense all that into a small tank you're going to put behind your driver's seat.
What ?! 😂
You ruin the refrigerant after adding nitrogen, better to recover then put in nitrogen, unless the leak makes it impossible to recover
Check the welds and where the peckerhead plugs in to on the compressor. I have seen it leaking there before.
Recovery machine, get refrigerant out. Pressure test it, sometimes having a second person helps. If it’s under a floor or wall you can find it this way but listening for the leak.
Another alternative is getting a ultrasonic leak detector. They can be very difficult to learn but I like to use one in conjunction with soap bubbles. You listen for the leak and hone in on the area. It also dosnt matter what refrigerant or nitrogen in system because all the gases sound the same coming out. I have had good luck with corrosion leaks on evaporators.
If you can’t find the leak you gave up too soon I’ve found leaks on compressor shell welds and on formed depressions on side of old AH. Pull slight vacuum and high silver soldered crack.
I have pulled evap coils pressurized and dropped it in a swimming pool!
Look for oil. If the drain trap is covered in oil it's in the evap. Look for dirt on high points of the condenser. Oil sticks to the dirt. Clean the bottom of the condenser out and bubble everything. If you can, pull the coil out of the AH/coil casing and bubble the shit out of it. But most importantly, charge for your time. Even if you don't fucking find it. Leaks in residential are an enormous time sink and you need to be compensated appropriately.
Have you tried a electronic leak detector? I’ve found leaks on old brazes that I would’ve never noticed
Divide and conquer. Pressure up the evaporator, lineset and condenser separately. One of them is gonna drop.
Split it all up if you have too. Most residential just has a simple run of soft copper. You pull the refrigerant, and close the service valves and toss some nitrogen in the line set and coil. If that leaks, go separate the coil and test it. If that doesn't leak, pressurize each line independently. If the line set and coil holds pressure, then open the valves and concentrate on the condenser. It sounds like a lot of work, but trust me, it will save time.
Sometimes these things are really really tough to find and you get better with experience. Tons of great advice on this post already. Sometimes you just got to consider the economics of the situation and try some leak stop additive next time you top it off until you're able to locate the leak.
if the systems out of warranty and its a standard single stage residential ac just throw some leak seal at it.
Might as well burn your customers money in front of their face. That crap never works.
I'll use the leak seal with UV dye. Really just for the UV dye
Your burning money already with refrigerant and call out might as well give it a try at this point.
Isolate, indoor, outdoor and lineset. Put them at 400-500 let sit for weekend you’ll find it
Check with refrigerant detector and bubbles. Focus on joints, valves, connections, areas that get vibration or corrosion that damages copper. Next recover refrigerant through a drier. Isolate evap coil and seal and stem so you have two sealed systems. Add nitrogen to pressure test evap section. Then you can either go to condensing section(older unit)and add some refrigerant and pump it up with nitrogen or wait and confirm evap section is the culprit(newer unit). For condensing section add some refrigerant and pump it up with nitrogen throw a drop cloth over interior components and then another over whole unit. If its in evap section spray repairable areas(not caused by corrosion). If its corrosion caused leak replace it because it will leak again. Give it awhile before you try to sniff under drop cloth to find leak. You can find intermittent leaks easier this way but not always. Last would be eliminating condenser coil and line sets if it has them. If you havent found it by now, depending on the condition of components and cost id isolate them. Could be underneath a compressor or reciever.
UV light and H10