Older big Sullair will NOT kick out at normal cut out

by Charley
(Dallas, Texas)

We have a big Sullair electric compressor that builds air right on past 160 p.s.i.

The adjustments on the Allen-Bradley control do not control.

I have metered the control and see that the voltage to the normally open solenoid valve is normal and as I watch, the voltage does shut off at the desired setting allowing the valve to be open again.

I have had the solenoid valve off and apart and it looks okay and the coil does actuate the valve.

I'm thinking the valve may be bad and I'm missing the problem.


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Apr 10, 2015
Does it vent?
by: Carl

As you have tested the load solenoid it sounds like your compressor isnt venting from the seperator? When the compressor reaches the desired pressure it should activate a vent valve which vents the excess air through the air filter. Can you hear it venting? If not then look in your manual for the vent valve or trace the small pipe from the air filter (or near the inlet valve) and see if you have a problem there.
To confirm whether it is working or not, after it has reached pressure, swith the machine off, does the pressure in the seperator tank drop? How quick?
Let me know by replying on here

Hope this helps


Apr 10, 2015
stops, but not really?
by: Doug in s.d.ca

Near as I can tell:
You refer to the "solenoid valve", apparently connected to the pressure switch.
Where is this "valve"? Or is it a relay with contacts that power the motor?

Maybe post pix and/or a model number?

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