Jun Air 6 not maintaining air pressure

by Premasiri
(Dubai U.A.E.)

Jun Air 6-25 air compressor

Jun Air 6-25 air compressor

Dear Sir,

We are using jun air 6 in our work shops and having same of 6 units.

two days back we relocated one unit.

after relocating we find this unit is not working as before.

Our require presser is 10 bar continuously and before relocating it was automatically maintaining the same.

after relocating the tank presser is going up to 15 bars stopped and air leaks from small outlet below on and off switch and come down to 12 bars and again goes up to 15 bars leaking the air runs again without stopping.

Please explain how to re adjust the machine, we want to have 10 bar presser all time and the this unit should maintain the same presser automatically as before.
Hello Premasiri... First off, 10 bar is 150 PSI. When I look at the Jun Air 6 series of air compressors, I see that there are a number of models:

6-4 Base Unit 1.77 cfm 2.12 cfm 120 psig 1.1 gal
6-10 Base Unit 1.77 cfm 2.12 cfm 120 psig 2.6 gal
6-15 Base Unit 1.77 cfm 2.12 cfm 120 psig 4.0 gal
6-25 Base Unit 1.77 cfm 2.12 cfm 120 psig 6.6 gal

I do not know which you have.

However, all of the current 6 series have an upper pressure rating of 120 PSI, or about 8 bar, so I am puzzled how you can be getting your air compressors to deliver 10 bar consistently.

Typically, if you require a consistent stream of 10 bar air, you would have an air compressor that would both cut out and cut back in at a pressure higher than 10 bar, and then use an air regulator to take the air stream to the air tool or application to the 10 bar pressure needed.

As to the continual cycling of the Jun Air compressor between pressures, what I suspect has happened is that, in the moving of the air compressor, tank debris has compromised the working of the tank check valve, and when the air compressor shuts off at cut out, and the unloader valve opens to dump the air over the piston, after that air is gone, air then continues to leak out past the tank check valve and out the now open unloader valve.

Dump all the air in the compressor, power it down, remove, clean and replace the tank check valve.

If that doesn't work please post a response as a comment here.



Comments for Jun Air 6 not maintaining air pressure

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Apr 19, 2016
Check Valve it is
by: ZG1000

Air was blowing out of the Unloader Valve on my Jun Air Model 6 when unit shut off so I followed your advise and pulled the Check Valve. Upon taking it apart I found debris on the O-ring...cleaned it up and now everything is nice and tight and not leaking air. Thanks!

(You are welcome! :-)

Jun 30, 2014
Jun Air model 6-25 Compressor leaking air
by: Peggy

My Jun Air compressor is leaking air from underneath the on off switch. I believe I have model 6-25. In reading other posts I believe it is the check valve that is leaking. The compressor runs but I can hear it leaking air. If left running it eventually overheats and cuts off and the air all leaks out. How do I fix this?
Thank you
Remove, clean and reinstall the tank check valve. If that doesn't work, and the check valve continues to leak, replace it.


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