Jun Air compressor not filling to 10 bar

by horner
(san diego)

At work we use a Jun-air compressor with the Witschi ALC 2000 pressure tester for testing watches. The compressor model is 6-4 and it appears to be rated to 16BAR. The compressor will consistantly fill to 9 BAR for multiple tests in a row, but will not fill our pressure tester to 10 BAR (even for a single test). Honestly, maybe it is just as simple as turning a couple screws, but i am really a rookie here and know nothing about compressors. Please help, the more detailed the better. I have looked all through the manual and am still unable to figure this thing out. Thank you in advance for the assistance.

---

Bill answers...

Hey Horner, nice to hear from San Diego.

You know, I sold Jun-Air compressors for a few years when working with a fluid power distributor. They are an excellent product, with long life...and man, are they quiet!

If the unit is rated for 10 bar, and I'm sure it is, and all you get out of it is 9 bar, then you've got a problem with the mechanical end of it, a pressure switch that's failed or failing, or...your pressure switch is set too low.

Opt for fixing the last item first!

I don't recall exactly how to adjust the pressure switch on the Jun-Air compressors, but my memory tells me that they are adjustable.

First, make a note of the cut-out and cut-in pressures that you are seeing now.

Once you drain the air from the tank and lines, pull the power cord, and pop off the cover of the switch, you should see a couple of nuts at one end of the switch. These are the high and low pressure setting nuts. If they are sealed, don't touch them. Talk to Jun-Air first.

Many pressure switches will indicate which of the nuts adjusts the cut-out and the cut-in pressures.

If they are not sealed, then rotate one of the nuts one quarter turn to tighten the nut on the threaded stud.

Be careful. Now you are going to plug the unit back in and watch the pressure cut-in and cut-out to see how it varied from before you adjusted one of the pressure switch settings. Once you see a change, then adjust the appropriate nut accordingly.

I would very much recommend that you contact customer support at Jun-Air's local distributor here to confirm how to adjust the pressure switch, and to help diagnose your problem if the pressure switch isn't it.

Cheers,

Bill