I recently purchased a 6 gallon 175 PSI compressor from Harbor Freight. The compressor works correctly, but I can't get the fitting on the hose to index the quick connector fitting on the compressor. I compared the quick connector to another one I have, and it appears that the collar does not have enough travel for the male 1/4" connector to engage it. Has anyone else had this problem, or does anyone have a solution? Thanks.

4 Answers 4


There are 2 common types of connectors. Unless your female quick disconnect is a universal one, and you will need to get the other type of connector. This is assuming that you are pulling back on the sleeve on the female while pushing the male into the connector. The automotive type has a wide band close to the end of the male and the standard or generic is a taller narrow bump.

  • I was going to suggest a picture to confirm, but this was my thought as well. There's more than one kind, but I've only ever used "the more common" one (not sure what the names are!).
    – JPhi1618
    Commented Feb 20, 2020 at 16:02
  • 1
    "Industrial" and "automotive". In construction everything was of the industrial type that I encountered. That's also what comes on most compressors, in my experience.
    – isherwood
    Commented Feb 20, 2020 at 16:38
  • I did find industrial as the name also but you beat me two it, I believe all of my Compressor’s did come with industrial also.+
    – Ed Beal
    Commented Feb 20, 2020 at 17:06
  • Classic H.F. product, owners manual says it comes with "Air Hose Plug Style Automotive (M) or Industrial (A)". manuals.harborfreight.com/manuals/56000-56999/56829.pdf . Maybe look for sticker or checked box on packaging? Commented Feb 21, 2020 at 16:03

I have found that the Fortress has a different type than what I am used to. Mine work but if I leave connected the tank will lose pressure over a short period of time. I have the automotive type. They say to buy new matching male female and the issue will go away.

  • Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, you should probably take our tour so you'll know the details of contributing here. Commented Jun 7, 2020 at 19:22

I once paid $10 for a couple hundred pneumatic connectors at an auction. I sat down to match them up, and painted them by type. There are at least four types to say nothing of different pipe sizes.

So it is not a surprise to find almost compatible air fittings.


I had the same issue, but figured it out. It is a push to connect female adapter, so shove the male piece in with a bit of force and it should snap it.

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