Leaks are crappy to find. I have pretty much went to only doing isolation tests... Reclaim freon, Cut the copper at the evap. condensor weld on a stem on the evap and lineset. Blaze all ends shut and pressure to 350, return next day and check levels... Bam, done son!!!! Good luck dude! I find dyes, and easy seal seem to cause restrictions.... Get a H-10, it's worth it

 

Thanks.

I felt bad I told the customer they had a leak and I just couldn't find it. Is it possible they could be at a place you just couldn't see? And shouldn't I be able to hear it?

 

There are plenty of places leaks can hide and not see them. There could be multiple microscopic leaks. It may not be just one. Old copper can fracture. Rubbed areas where tunes touch other metal parts, end sheets on coils.

 

I should also add that I didn't reclaim anything I just pumped the system down into the condenser

 

All good. It could be anywhere... I always ask if they have had any construction done lately and ask about someone hanging things... You know what the problem is, so that's half the battle... You can spend hrs. Or days trying to find a leak... Usually the evap metering device is a good place to check...take the panels off, if it's a a frame coil, open it up... I had a leak in a wall once I could t find.... Customer hung a pic in the bathroom, nail barley pierced the line. Then stayed in it and leaked really slow. Took ISO. Test and 3 days to find

 

I use the Dye in such cases.
99% of the time,it is in the Evap,coil,Finpack and,
may just be on the Inlet,Airflow side,which means,you will have to remove the Inspection cover,of the Evap to SEE It.
Then,again,you will have to be 'diligent and look for the 'obvious' such as a tiny 'hole' at a braze joint even on the Liquid line.
As to 'hearing it',Maybe,but no such Luck 'sometimes.
The Dye,Don't Lie....

 

What dye do you use?

 

This is just me, but The Lord has blessed me with great hearing. I usually fill with nitrogen to high side test pressure, and if it is a size able leak like that I can usually hear it if the kids in the next room are quite. I did install a Fujitsu one time that while pressure testing I couldn't find the small leak that showed on my gauges. Ended up being my low side ball valve.

 

Thanks I really appreciate your input.

Not going to lie just starting out I feel like a hack and I hate it. I can't wait till I get some confidence when it comes to diagnosing and repairing.

 

Gotta be confident in yourself....your always gonna be against you

 

If you have the time. The isolation test is the best way to find it. Pressurize the evaporator coil, each copper line and condenser separately. If it only takes an hour to lose 60 psi, then it should be pretty easy.

 

Thank you so much for your answers.

Discovering this site is invaluable having access to so much knowledge at my finger tips.

 

Not sure if you caught it, but someone mentioned H-10 in this thread. That's an electric leak detector. They're pricey, especially if you're new to the trade, maybe start saving for one now.

They will pick up one half of one ounce per year leak, so they are plenty sensitive. What you do is get good at using one of them babies, and there will never be a leak you won't be able to find. You sniff around with the leak detector on the most sensitive setting, then when it starts going off, you start looking for oil.

If you don't see any oil, then change the setting on your leak detector from small to medium, and sniff some more. Once you get closer, then you will know where to put the soap bubbles to confirm the leak.

I'm new to the trade been doing service for 4 weeks.

I went to a leak check on a residential unit yesterday and couldn't find the leak. I pressurized the system to 260 psi with nitrogen and soaked all the braze lines evaporate cool and condenser with bubbles. I couldn't find a leak anywhere. My gauge dropped from 260 to 196 after an hour which tells me there is a good size leak somewhere.

What am I doing wrong that I can't find it has anyone else not found a leak before? How can I improve my leak checks.

 

You say it dropped 60+ psi in an hour and this had refrigerant in it to pump into the outdoor unit? If you are looking for a leak that big chances are that refrigerant wouldn't be there.
Leak checks are easy. Pump up system with 200 psi of nitrogen with a trace charge of R22. Take your H10 out and quickly locate leak.

 

The service valves might not hold, and some of your 260psi probably bled by the valves into the condensing unit.

 

service valves might not hold, and some of your 260psi probably bled by the valves into the condensing unit.

Not 'likely' but 'possible'.
Your 'under the gun' and 'Expectations are a reality,so, just 'do' what you need to do,with in Reason and let IT roll.
Get the Cool on and 'deal with this as you can because,Tomorrow is another Day and the 'problem' Will present,Itself.
WE are not magicians and some times,IT takes Time for the Truth to Come forth.
Be patient and Wise in your Choices.
No 'sense in cutting and ripping things apart when you just need to slow down and start over.
You have an Obvious LEAK.. Use your skill's to Find IT.
IT will be something 'done' to the System as in a braze joint or God forbid,a nail thru the s'rock or as I found,the Roofer's in the attic lineset with Their 2" nails..

 

Don't forget the possibility of the line set if placed underground being the leak location. If your sniffers, dye, and bubbles don't show it, it is time to isolate the line set at the service valves and evap. Make a u connection and pressurize them.

 

He doesn't have a sniffer. All he has is soap bubbles. Probably doesn't even know what we are talking about when we say sniffer.

 

Get an electronic leak detector. As said use a trace of r22 and nitrogen. I pressure test at 400psi and I have written instructions from trane to go that high (I'd go that high anyway if needed but if anyone wants to argue...)

If you have an out of warranty coil that has a leak and some free time strip it down and visually find the leak. You will then know why soap bubbles on a coil is a waste of time. When you strip it down to the tube and the leak is so small it turns the soap bubbles into shaving cream you'll know how you'd never see that otherwise.

 

Are you introducing nitrogen through both liquid and suction line? Correct me if I'm wrong but only going through the liquid line might cause nitrogen to leak through txv causing pressure drop?

 

I think on a non heat pump if you pressurize the evaporator through the suction side only.

 

Just a good practice- soap your hose and manifold connections when doing a pressure test, especially if its going to be a long (hours or overnight) test. You may see some settling of the pressures between the two sides, I usually wait 15 min or so before making my baseline reading of the standing pressure.

 

Thank you all for the advice. I will invest in a leak detector. How much r22 is needed for a trace gas when using a leak detector.

 

10% will do. Put the freon in first (i.e., 250 psi? put in 25 psi of freon first, push nitrogen in to 250psi). Use gas, not liquid.

Also, if you're interested a detector that fits your budget, post in the Tools & Test Equipment forum first to get opinions. Could save you money and heartache.

 

To find leaks, you must first have the proper tools. Soap bubbles are only a very limited part of what's needed.
If I need trace gas, I only use a very small amount. It sounds like your leak is rather large so you'll probably only need a shot. And you'll be good.

 

It's probably buried in the coil. Or in the rear u-tubes where you can't see unless you pull it. Dye doesn't cause restrictions and is also an excellent tool.

 

Maybe it's the people I come behind then. I swear they put a leak check dye. 2 weeks to a month I'm out there and findin. A restriction or comp. failure... But then again, I always pull a vacuum after I am messing with the lines.. What do I know

 

I would recommend using a dye, then come back and check it

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

A 1/2# or so.A 'sniffer will only detect the 'Freon' and not any Nitrogen,so you have to 'introduce' enough Freon to circulate thru the whole System.
You have a 'bad' enough leak to Find.And as I said,get up on your toe's son,LOOK for the Obvious.....
Weld joint's that is......Mechanical,Anything that was,
Installer,Installed.....

 

That fast of a leak use a ultra sonic leak detector, quick and easy. Keep reading on here, there is many tricks and tools to find leaks.

 

I've been getting some dye calls also. Some of the newer dye has a sealer in it

 

:eek2:

 

If you have the refrigerant isolated in the system, you never want to pressurize with nitrogen above the refrigerant pressure in case a valve is leaking by.