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.



Comments for Jun Air compressor not filling to 10 bar

Click here to add your own comments

Nov 26, 2010
10bar compressor ,pumping only 8bar now
by: Anonymous

hi i did notice that my compressore recntly start pumping only 8Bar but before was solid 10Bar, but now is really freezing and wondering is that ambient temp my reflect that?

May 05, 2009
Thank you!
by: Anonymous

Thank you Bill. I greatly appreciate your help. We will give this a try and i'll let everybody know how it turns out.

Click here to add your own comments

Add your own question or comment. It's easy to do. How? Simply click here to return to Jun-Air Compressor Issues.

Jun Air model 40BD3 doesn't build pressure

by Jason
(Inman,South Carolina,USA)

Hello I just purchased a Jun Air compressor model 40BD3. I wanted to use this unit in my home garage for one I got a good price and its compact. Once I got the unit hooked up and tried to test it the unit came on and sounded great. As the compressor was running I was watching the gauge to see how it was pumping up and it seemed to be coming up slow so I let it run and eventually I just turned it off. It reached around 80psi when I turned off the switch. Once that happened I contacted Jun air about this unit and they were very helpful in telling me more information about this unit. However the cost of repairing the pumps if that is the issue is way more then Id be willing to spend for my application. I was going to try and test each pump to see what the pump up time was for each one to see if it was the pumps or if mabie the dryer system has a block somewhere in it. I wanted to get an opinion on what this unit is worth in this condtion and just try and get out what I have in. It has around 7000 hrs and is a 2000 year model. If it was a easy fix I would attempt it but I cant afford to replace pumps its just not realistic. If you could help give me some idea's here I would greatly appriciate it. Thanks Jason

Bill says...

Jason, maybe you got a really good deal because it wasn't running right.

Check out this page for reasons as to why a compressor will not build pressure.

The unit you purchased is expensive, I'm sure, as all Jun-Airs are pricey. What you are paying for with that price is reliability and quiet. Sometimes applications are such that you can't have a compressor making noise, and Jun Air builds very quiet compressors.

Check their website for their local distributor to ask them the price.

The cost to fix will depend on what's failed.



Click here to post comments

Add your own question or comment. It's easy to do. How? Simply click here to return to Jun-Air Compressor Issues.