Compression fitting won't fit on evaporative cooler supply line

There's a section of my supply line to my swamp cooler (1/4" copper) on the roof that had a small crack in it. So, I figured I'd just cut out that small piece and use a compression union fitting to connect it back together. I got the compression fitting from HD, in the section with all the swamp coolers and cut my line. However, the compression sleeve is too small to fit the copper tubing, and so is the threaded part of the fitting that the copper line is supposed to go into. It's not just a tight fit, either - there is no way it's going to go on.

Am I doing something stupid here, or is there something I'm not getting? I've used compression fittings before (on bigger pipe), so I know how they're supposed to work. I cut the tubing with a hacksaw and then cleaned up the ends, so I don't think I deformed the tubing significantly.

Thanks for any ideas.

some times they can be a pain.

your pipe is not round. plain and simple.

use the compression fitting [without the nut or ferrell] as a resizer/reform,

shove the pipe into the fitting to "reform" it.

if that does not work, use a flaring tool block ,,,to reform he pipe.

if that does not work

use a cresant wrench,,, place on a "good" pipe,,,adjust wrench to that size,,place on your pipe and reform it


i have, set the Ferrell onto the pipe, then "GENTLY" tapped it onto the pipe,,,then, tapped the pipe into the fitting
driving it thru the ferrell...finesse is the word here,,,force it onto the pipe with out fugg'n it up


in my opinion, the small crack, on the roof, was where the pipe swole up from being froze....right?

Yeah, it just turned out that a bigger section expanded than I realized. I just replaced that whole section, and everything's good! Thanks for the input.

Try rubbing some water on the outside of the tube or on the inside of the compression fitting part that you screw in. I had a very snug fit with my tubes also, but I got them on there in the end.

sparrow4 said:

Try rubbing some water on the outside of the tube or on the inside of the compression fitting part that you screw in. I had a very snug fit with my tubes also, but I got them on there in the end.

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