Bostitch Air Compressor Model CAP2000P-OF won't shut off

by Noel Ilao
(Calgary, Alberta Canada)

I have replaced the Pressure Switch 4X already with brand new ones from Bostitch OEM Parts.

What are the chances that all 4 of them are defective?

The compressor still won't stop running after reaching the 150 PSI Cut Off. It reaches 160 PSI then the Pressure Relief Valve open up. I have checked for obstruction making sure that the pressure reaches the desired setting.

The location of the Pressure switch is just below the Gauge so I am sure the pressure is going higher than 150 PSI until it blows the relief valve.

Please advise as I am stumped.

Thank you.

Comments for Bostitch Air Compressor Model CAP2000P-OF won't shut off

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Jul 17, 2018
Bostitch Air compressor
by: Noel

Thank you for your responses. I have done all the things that you guys had recommended from turning it off manually and even replacing the pressure switch with a different brand to adopt.

I made sure that the pressure gauge is reading it right also.

I called the Service centre here in Calgary AB and they only advised to check any obstruction which
is not very clear.

I hate to just throw this compressor out because it is in great shape.

I know in the US, these pressure switches are only $15 but here in Canada, they cost $45.00 ea. So I am already out $180 almost the price of a new one.

Jul 14, 2018
CAP2000P-OF pressure switch
by: Ron W

I had the same issue but my problem was not the switch it was the diaphragm, wich is just neoprene gasket material, I don't know how a bostitch is built but some sort of a device has to read the pressure. My compressor is an older Ingersol Rand. a picture of your compressor and switch would be helpful

Jul 14, 2018
CAP2000P-OF won't shut off
by: Bill

If the pressure switch was a manual switch, to stop power flow to the compressor motor, you would switch it off, thereby cutting power from the wall socket to the compressor motor and the motor would stop.

If you switched it off manually, and power continued to flow across the switch to the motor even when switched off, you would correctly conclude that the switch was broken, replace it, and ensure that when you turned if off, power would stop flowing.

It is the same with an "automatic" pressure switch, except you do not have to manually turn it off your self. It's the pressure fluctuation inside the switch, as it monitors the tank pressure, that allows either the flow of power or shutting it off, depending on the pressure that the pressure switch "sees".

If the tank pressure reaches the normal cut out pressure and the compressor motor does not stop, then it has to point to:

1) The pressure switch is not monitoring the actual tank pressure and cannot react

2) The pressure switch has fused shut, is broken, has failed, and power continues to flow regardless of the tank pressure it is "seeing"

3) The pressure settings on the pressure switch are not as advertised and the cut out pressure is higher than the displayed rating

4) The pressure switch is wired incorrectly into the circuit and as a result the switch does not work as intended

I share your frustration, Noel. Yet, if power continues to flow through the switch after the tank pressure reaches the cut out setting, then it has to be the switch that isn't shutting the power off at the correct pressure for some reason.

"What are the chances that all 4 of them are defective?" There are such things as "bad batches" in parts manufacturing, just as there are switches that are mislabeled as to the pressure setting.

What can you do?

Temporarily replace the pressure switch with a simple ON/OFF switch to prove that the motor will shut off when the power is cut.

Acquire a similar switch with the same pressure range (of which there are many) from another source which is, hopefully, from another batch of switches and try it.

Continue to request info of Bostitch to ensure that the switch they are providing actually works the way it is supposed to.

I believe these switches cost in the range of $15 to you. That means that at the manufacturing level they may only cost $1 or so. You don't get a lot of quality in an electrical device that costs essentially pennies to make.

Good luck and keep us posted, will you?

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