I have a small air compressor that I am trying to figure out how to adjust the pressure switch. There is an example diagram but either the thing is broken/worn out, or I am just doing it completely wrong.

It can be adjust for both cut off pressure and then the differential pressure.

A while ago I noticed that it did not want to stop pumping, so for a while I would let it pump up to 120-125psi then I would turn it off. I did manage to make it stop pumping at the correct pressure. But now it is all messed up, it will run down and empty the tank but now it would kick back in at about 60psi.

So after messing around with it for a long time yesterday and today it will not stop pumping nor start pumping.

I want to know if the pressure switch is faulty or if I am faulty!

From what I can gather and have seen so far. The black plastic nut adjust the cut out pressure ie 125psi.

Then the diagram shows to loosen off the small nut, and then adjust the Delta up or down.

After I have loosened off that nut, from what I understand you have to use the spanner on the same black plastic nut to then adjust the cut in pressure.

But, by undoing that little nut then adjusting the larger black plastic nut what is supposed to happen? Because sometimes the whole threaded shaft turns, and some times it does not.


I think that either the threaded rod has to turn (with the black plastic nut) to adjust the differential, and then to adjust for maximum pressure the you turn the same black plastic nut but this time the threaded shaft must not turn. Or it is the other way around.


This pressure switch is not the same style as ones I have seen on the internet, and I don't think I have seen it on this website either. So I wonder how exactly do I adjust this, is it broken, is something slipping when it is not meant to? Would it be fixable, and what is a compatible pressure switch to fit in case this one is no good?

Where is the differential adjustment? The photo just shows the high-end adjustment nut.

Yeah that is what I want to know too. From the sticker that is on the side of the cover I think you have to adjust the big nut for the max cut off PSI. When you do this that lock nut should hold the whole assembly together and both the plastic nut and the threaded shaft would spin.

Then to adjust differential, you would unscrew that locking nut. Then adjust the differential by spinning the same black plastic nut, but I think now this time that threaded shaft is supposed to not turn as you do it. If it turns now it will just be the same as adjusting max pressure.

This is how I am understanding that it has to be done. Would you agree. It sounds like you have never seen a switch like this before either?