I'm installing a mini-split, and in a moment of carelessness I slightly kinked the 3/8" copper line (the larger one). I repaired it using the 'wrench method' with some nylog to lubricate, and now it looks like this:

side view side view

enter image description here bottom view

The scratches you see are very shallow - I cannot feel them with my nail. I suspect that if I were to lightly sand the entire section they would all go away - I think it just took of the dull surface and revealed the shiny new metal.

I could cut this section off, and add a new section of line set, joining them with a flared coupling (same as used at either end of the line set). But that introduces two more joints as possible points of failure for the future. It's not clear to me which will have the better longevity - the unkinked section of tube, or an additional two flare joints.

If this were your house, what would you do?

(A third option is to replace the entire line set, but it was a big effort to wrestle this one into place through a crawlspace)

  • Any chance you have a picture of the kink?
    – KMJ
    Commented Feb 21, 2023 at 6:00
  • Sanity check: You haven't pressurized this system yet, correct?
    – keshlam
    Commented Feb 21, 2023 at 6:40
  • 1
    @keshlam That's a good point, most DIY mini-splits come with pre-charged lines. If so, OP would have to hire somebody to recover the refrigerant, and after the repair, purge, evacuate, then manually charge the system. At that point, you might as well have the tech do a brazed repair.
    – user71659
    Commented Feb 21, 2023 at 7:25
  • It does not look healthy, only a pressure test will tell.
    – Traveler
    Commented Feb 21, 2023 at 7:35
  • @KMJ those are the best photos I have. The kink is located at the fulcrum, where you can see I slight flat spot.
    – tom
    Commented Feb 21, 2023 at 12:41

1 Answer 1


Your question: "If this were your house, what would you do?"

I would leave it alone and use the line. A splice would be a greater interruption in flow.

Get the system up and running. Then you will find out if any other repair is necessary. Otherwise you may be spending money and time on unneeded repairs.

  • 1
    Upvoting this - it's where I would go too. If it's going to fail it's quite likely to fail during pressure testing.
    – KMJ
    Commented Feb 21, 2023 at 16:07

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