You plug it in, or turn it on, and the compressors runs but there is no pressure built. If this is the case with your air compressor, there are a few things to check.
The air compressor may be building pressure, or trying to, but it cannot due to a major leak on the compressor. One thing to check right away is the tank drain valve. If you leave your compressor tank drain open between compressor uses, as many folks do, make sure that the tank drain is closed before the compressor is started. Otherwise, air will drain out of the tank as fast as it goes in and you have a compressor that runs but there is no pressure built.
If there is an air line plugged into the coupler of the compressor, what’s on the other end of the air line? It is possible that an air tool or blow gun or some such is open and bleeding air out as fast as the compressor pump can compress it.
Often it’s the compressor pump that’s the problem
If could be a massive leak that is the reason why the air compressor runs but there is no pressure. But not typically. It’s the pump that’s the problem most of the time.
If an air compressor is running, and there is no pressure being built in the tank, and there are no major leaks, then it’s time to check the following:
Air exiting through intake valve?
While the pump is running, is there air blowing out of the pump intake? Whether that’s consistent or intermittent, if air is coming out of the intake, it’s a pretty sure sign that the valve or valves in the pump head are failing and it is time to tear down the pump and have a look. You may want to look for a rebuild kit for the make and model of compressor, as valves may be just part of the kit.
Pump piston rings failing?
The rebuild kit may also contain piston rings. Besides the fact that the compressor runs and no pressure is built, another indicator of piston ring failure is air blowing out of the oil fill tube.
If there is a serious piston ring failure, not only will there be air exiting the oil fill tube, quite likely there will be oil too, particularly if the sump is full.
Air coming out of the oil fill tube, whether a little or a lot, means that there is piston ring failure. A tear down is necessary, and when doing so, make sure the inside of the cylinder is inspected to make sure it’s not been damaged by metal-to-metal contact as the piston cycled with worn rings.
No air coming out of the intake port or out of the oil fill tube?
Consider the pump gaskets!
At the top inside of many air compressor pumps, along with valves or valve plates, there are gaskets. Depending on the pump, there may be one, two or many, all different shapes and sizes.
These gaskets are there to ensure that intake air stays on the low pressure side of the pump until it cycles, and then drives that air into the tank via the high pressure valve.
Over time, particularly with cheap, import compressors with questionable fit and finish inside the pump, a section of the gasket will let go. It may occur when the compressor is starting, or it may manifest itself when the compressor reaches a certain tank pressure, and the increasing force on the gaskets causes a breach. When that happens, air cycles back and forth inside the pump, but doesn’t get driven into the tank. The air compressor runs, but does not build any air.
If the symptoms related earlier about air exiting the oil fill tube or intake port is not happening on a compressor, yet the compressor continues to run with no build up of pressure, then it’s likely that there is a pump gasket failure.
Once again, it’s time to tear down the pump.
Your air compressor runs but there is not air built up in the tank? That being the case, I sincerely hope that when you Google a pump rebuild kit for your compressor make and model that you find one that’s not price prohibitive and, upon receipt, take apart and rebuild the pump with good success.
I am having the same problem that Killeen Conley mentioned about a year ago. Pressure builds to about 85 or 90 psi but never high enough to shut off. Porter Cable CFBN125-3a 150 psi 6 gallon compressor. Thanks in advance
My Porter Cable Air Compressor will reach 150 PSI in the Pressure Tank (gauge) but zero pressure on the regulated Pressure gauge. After about 20 minutes the 150 PSI will drop to 100 PSI without any use. There is no detectable leak on any of the fittings, connectors, etc. no Electrical problems evident and it’s plugged directly into a 20AMP outlet With a 20 AMP circuit breaker
I Have a speedaire 1nnf6b and the compress runs but no pressure is being builT, the pressure release DOESN’T leak bad enough and air doesn’t come out the intake, i thiNk my tank valve is bro but that isnt the issue, if i let it run then pull the purge valve nothing happens.
Kolleen, this page that I moved your post to offers some things to check when an air compressor runs but doesn’t build the pressure as high as it’s supposed to. Please have a read of the page and if you still have questions, add a further comment.
My compressor only gets as high as 90 PSI and not 150 PSI. I have checked various places where there may be an air leak and tightened all values. Any suggestion of how to raise the PSI. I am trying to fill a tubeless tire.
Larry, did you check the things referred to on the page where you left your comment? Just wondering?
My Craftsman compressor worked fine yesterday, today will only pump to 30lbs
Anyone know what to chexk? Oil is
Alan, if the compressor is making air pressure, but neither gauge registers that pressure build up, how do you know the compressor is building air? What is the make and model number too, please.
My compressor does build up air but neither air gauge registers. alan
check if there is enaf oil in your oil chamber and also make sure there is no dirt and some carbon accumulated on the flap valve , I’m sure that will help
Make and model of air compressor? So, the compressor runs and runs but builds tank pressure up to but not past 30 PSI, is that right?
The compressor still runs but pressure build is 30 Lb/in2(PSI) and goes below that point too and never regain the pressure while using.
Your suggestion would be highly appreciated.
Hello Michael. I moved your question to what I believe to be a better location on this site. I doubt very much if it is the pressure switch or the “regulator valve”, assuming that what you mean by regulator valve is what I call a pressure switch, that is the issue here. The pressure switch is a dumb device. This means that it is either passing power to the motor circuit or it is not, and that is based solely on the pressure it is experiencing from the air in the tank. It does not modulate air pressure from the… Read more »
I have a speed aire model nbr 4B217 it will only pump up to 80 lbs of air no higher and takes about 10 minuets to get up to that. is this due to the fact that I might need a new compressor regulator valve ? Or dose the compressor need rebuilding? Of course I do not know if it will shut off once it reaches a certain psi. because it never reaches that high. Any help will be appreciated.