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pressure testing refrigerant lines

Ted_9 Member Posts: 1,718
Guys, I'm having a hard time finding leaks in two lines that we ran. They are new copper line sets for R410A. The leaks are small and I notice the drop when I fill to 200 -250 psi.

And yes we use nitrogen to pressure test.

These are Unico sir handlers and we swapped out the R22 TXV's for R410A ones. So right there there could be a leak there.

I've never had such a problem finding leaks.

Any advice?


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  • Big Ed
    Big Ed Member Posts: 1,117
    Bubbles Bubbles will Cure Your Troubles

    Spray every thing with soap leak finder... Yes hit the txv but hit the coil and brazes too.. Could be a leaky manifold or worn hoses as well... Condenser shut off is also a good place to look.... Any fitting along the line set.....
  • clammy
    clammy Member Posts: 3,092
    ref leaks

    When they are real small try ritchie line flurencant dye using a uv light the kits are pretty cheap about 50 to 75 bucks and work very well for small leaks in locating them when they can't be located with bubbles it's saved me a few times on very small equipment leaks like on commerical air dryers peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • don_185
    don_185 Member Posts: 312

    Isolate the lineset from the condenser and the airhandler
    and pressure test all three.

    It sounds like you may be assuming that all is well with the evaporator and condenser.Sometimes that not the case.

    I have many of evaporator and condenser with leak in them
    right out of the box.

    Sometime a trace of refrigerant on top of the nitro and
    a good leak detector will do the trick.

    Happy hunting my friend...they can be a pain to find at times.
  • dmy hvac
    dmy hvac Member Posts: 33

    hi i run into this problem bout once a week all i pretty much do is refrigeration i have a d-tek electronic leak detector that works great can put you in the right area on high sensitive level if you stick it near the condenser or evap it will go off so you atleast know what area to look into then set it to low for a better pin pointing then use soap bubbles from there.if you can notice the pressure dropping while looking at your guage thats a descent size leak ive had them small where ive had to isolate (braze the lines to condenser and evap)and pressurize both to try to figure out which side was leaking.if i were you id buy a d-tex detector or borrow one just mix some r22 or 410 with the nitrogen.also shut off all noises in the area you are looking to see if you can hear hissing.after working in big super markets ive learned leak checking can be an art in itself "boring and frustrating"

  • I agree with the isolation method as a last resort, helps you narrow down your search. One thing I have discovered when mixing nitrogen and refrigerant for leak testing is that the nitrogen will push the refrigerant away from the point of entry so that in some cases only nitrogen is coming out at the leak site. I fill my system to full refrigerant tank pressure and then SLOWLY bleed in my nitrogen. Sometimes letting it sit idle overnight will allow it to mix better and even collect in the area of the leak so you can pick up a sign the next day. I've also heard of putting baggies or even garbage bags over suspected components overnight and then checking the bag with your leak detector the next day. Good luck!
  • Jim Bergmann
    Jim Bergmann Member Posts: 24

    Windex maks an excellent test solution, make sure to spray down your hoses and manifold I have traced a lot of leaks to there.


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