# Air Compressor-No Pressure above 25 psi



## redbeardbrad

Hello! I bought a compressor off of craigslist awhile back. Craftsman 5hp, single stage, 240 volt, 20 gallon 9.3 @ 90 psi. 11 @ 40. From the start, pressure would not go above 25. After I replaced the switch (it was beat up) I got into the manual. Turns out the factory set cut off is at 25 psi. It said that I would need to put a regulator on to adjust the pressure. After i connected a regulator, nothing has changed. Do I need to switch the regulator I just bought for the factory installed gauging device? If so, can I screw my electrical switch into the pressure gauge port on my regulator and throw in a gauge somewhere else? Or will I have to buy a new device? (My regulator has air intake, outtake and pressure gauge ports). Please reply with anything and everything that I could be doing wrong here!!!! Thanks a bunch.
-Brad


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## SonnyT

Not sure what to say. I would think you would need a different cut-off swtich that is adjustable.


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## redbeardbrad

Can I put an adjustable cut off switch with a psi range of say 90-150 on it even though the compressor is factory set to cut off at 25? Is that safe? Thanks!


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## cedgo

Hello. Don't know why an air compressor would have a cut-off at 25psi. A single stage machine should at least make 100psi. Generally, most machines have an adjustable pressure switch. The regualtor will drop the main pressure to what ever you need, but the tank pressure should still reach the 90-100 psi range. That would be a safe pressure range. You need to make sure the safety valve is present and in working order. A pressure guage can be installed just about anywhere on the tank, as can your pressure switch. the switch needs to know the pressure in the tank, not the regulated air. Hope some of this will help.


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## rhenning

Are you sure you are not looking at the hose outlet pressure. Some of those are limited for questionable safety reasons. The tank itself usually is a lot more pressure than the hose. Roger


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## redbeardbrad

Thanks for the input so far guys, it has led me to check lots of things out, and, I think, has led me closer to understanding the problem. The new pressure switch that I installed says ON 100 PSI and OFF 125 PSI. I assume then that my pressure range from the tank should be getting to 100-125, and with 240 volts and 5hp it should have no problem getting there. But for whatever reason, the compressor still shuts off at 25 PSI (and that is the tank pressure!). So its not the switch....


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## 89yt12

is the circuit breaker ON the motor triping????


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## cedgo

Are you sure the pressure guage is reading the right psi?


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## pawon

Did you fix it already?

It also could be something else. Normally there would be some kind of motor temperature or current protection. Either one of these could trip... 

check carefully where the electrical power is cut off. Sometimes there's a temperature safety device installed INSIDE the electro motor... after stop, does it take some time, before you can start it again?

It could also be the circuit breaker as 89yt12 suggests. They usually have a overcurrent protection build-in. It will trip when you draw too high current for a too long time.

Good luck!

Pawon


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## FloridaGuy32

Don't understand why any compressor would be rated at 9.3 SCFM at 90 psi if it only goes to 25 psi, that's not even logical. Could be either a very low psi safety switch similar to the ones they put on oil less machines, in place of blowout valves, to prevent over pressurization or a faulty pressure switch (even "new" ones can be faulty). Outside of that it could be a bad motor or a leak that's causing it to overwork and trip the motor's reset. Lastly the pressure switch could be installed improperly or with an obstruction causing false readings... Good luck with that (10 years later 😅)


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## stevon

FloridaGuy32,

First of all this thread is ten years old:
Discussion Starter • #1 • Nov 18, 2011 
If I had a similar problem like this now I would start a new thread.
second I'm getting that compressor stops or trips at 25 psi in the original post although that is not stated.


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