Does not cut off and on as advertised

by Steve Lynn
(Anacortes, WA)

I installed a Square D 9013 pressure switch which is suppose to cut off at 125 and on at 95 psi. But it doesn't.

I've tried adjusting the springs per instructions but only the big spring does anything.

I can adjust the pressures up and down but I can't spread them out. I'm getting a cut off of about 115 with a cut on of 95. And not consistant.

I did not hook any pressure line to what looks like a check valvue on the pressure switch. I only hooked the bottom of the switch to pressure.

Do I need to add a hose on check valve to tank in order to get the pressure range I want?

This is a 4 cylinder compressor with 35 CFPM at 90 psi using a 5hp motor with 220V @ 24 amps. I'm at sglynn@us.ibm.com.

Thanks for your help.

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Bill says...

Steve, I don't everything about every compressor, but I some about a few. Unfortunately, I, and all of the readers, don't know what type of compressor you are referring to.

The range in the pressure switch is to build lag into the system, so the compressor isn't cycling on and off too often.

If you are able to adjust the two at the same time, and not widen the gap, why not set the cut out at 125 PSI? Wouldn't that solve the problem.

I don't know what the check valve is you refer to, and I cannot envisage what the supply air line to the switch is. The pressure switch obviously has to be connected to the tank so that it can "read" the pressure.

The think the valve you are referring to might be the Unloader Valve but cannot be sure.

Bill