Why Compressor Does Not
       Build Pressure

With so many questions and responses about why an air compressor does not build pressure, I am adding a number of pages of information to address this issue. This is another in this series of information pages.

Here is where you can post question of your own, or offer advice or a comment.

All new postings will be live on the forum for about a week to allow the original poster and others to comment. After that, if the content is relevant to the many visitors to this web site, I will make that post permanent, and move it to the appropriate page.




Air compressor does not refill?

by anonymous

Question:Compressor turns on fills up to proper pressure shuts off but will not refill with air unless i shut off the power and restart.

Response: When you say it will not refill, are you saying that when you use some compressed air, and the air pressure in the tank drops to the normal cut in pressure, the compressor does not start, or are you saying it tries to start and cannot? If the first, it could be the pressure switch not tripping to on when the pressure drops to cut in start level. If it tries to start and cannot, could be a bunch of things. Which is it, please? Bill

Comments: Jan 04, 2012 - air compressor does not refill - by: Anonymous

The tank does not even try to start back up while using air unless you shut it off and turn it back on.

Jan 02, 2012 - Kobalt unloader valve - by: Randy

At the pick up point when the pressure switch cut's in, the main breaker trips pulling 93 to 101 amps. But it's not consistent, it works for three or four hours good. Then it will trip, after resetting the breaker- it'll work for a while again. Normally a motor is good or bad. I wouldn't think bad capacitors seeing it operate normal for hours even when it's full or at normal cut in. Can't put my finger on the problem.


An intermittent problem at cut in might point to the pressure switch failing and shorting out... or, it could be an intermittent cap or motor issue. Depending on what is failing, you can get an intermittent motor or cap problem as the unit is failing. Did you test the cap?

A Pro Source air compressor model 1110C willl not build pressure.

by anonymous

Question:When turn on the pressure will not build up. It has oil. There is no water in the tank.

Response: So, your air compressor starts fine, runs, but there is zero, absolutely no, air pressure build up in the tank? Or, does a little pressure build up, and then, even though the compressor runs and runs, no more pressure builds? I need to know which, please. Post your response as a comment on this post please.

Suggestion: Are you feeling a vacuum at the intake port when the compressor is running? If it's just pulling, and not puffing back out, it's likely not your valve. If you are feeling a puff of air in between intakes, then it possible is a leaky or failed intake valve.

Comments: Jul 09, 2011 - pro source compressor model 1110c will not build pressure - by: Anonymous

it build a little pressure and the motor keep running. it build about 50lb.

Jun 20, 2011 - no air - by: Anonymous

have a 2 horse air comp, pro source, builds up pressure to abot 8 or 10 lbs no more, what can be wrong please?


First checks are always for air blowing back out of the intake port on the pump. If not that, and no audible leaks elsewhere, then it may be a gasket inside the pump has let go. See the TROUBLESHOOTING pages relating to air compressors that will not build pressure.

Wont reach cutoff pressure. no leaks.

by David Dollarhide (Montezuma de Cobano, Costa Rica)

Question:Hi. Just a working guy in the boonies of Costa Rica. Second details attempt. Stood up to grab my camera to upload a couple pics and tripped on the charger cord, kicked my laptop onto the (lucky) carpet. Restart. Perhaps I was going to get a little nip from the freezer too.

Problem #1: My buddy bought a p.o.s. chinese thing called a Gladiator CE 350 but to be honest, has served fine for 3 years. Keeps our motorcycles pumped up and runs an impact chisel or small paint rig okay.

I am painting the new gutters with an airgun. I made a homespun gasket to replace one under the pressure switch from an innertube, and it works fine. Parts are hard to get out here, and there isn't anyone within 80 miles I trust to take it apart except myself.

So now it doesn't reach the cutoff pressure, which is set at 100psi and it always did before. I run it up a while, with the output valve closed, shut it off, and it holds its pressure fine. No leakage. It's on its own circuit. Oil level is good, ( a little bubbly perhaps?) No water trapped in the ballast. Air filter is clean. Just runs. It's not reaching, and not cutting off. Did I just notice that air is coming out from the oil fill nipple (little orifice on the cap) while it is running? Didn't notice that before. So.. ask the computer, your site is first up, appears intelligent and worthy. I read and learn about a 'reed valve'? Is it located at the top of the piston where that tube winds over to from the tank?

Response: Delighted to hear from you David. Your compressor symptoms point to either a reed valve issue or an internal gasket failure. Please have a look at www.about-air-compressors.com/compressor-will-not-build-pressure.html page, which is linked from the troubleshooting section on the site map page, among other places. These pages will provide tips to help you check and determine what is causing your air compressor to run, but not build pressure.

Pressure won't build ~ Now it does! A success story.

by Charlie Dunn (Houston TX)

Question:2HP PANCAKE AIR COMPRESSOR BY CENTRAL PNEUMATIC: i want to thank you and your site for helping me solve my problem. after reading all entries in this section, i was able to fix my problem by simply removing the air intake filter and head to expose the reed valves. then a simple cleaning of the (2)reeds and flipping them in case one was distorted completely fixed the problem. cycles perfectly with compressor pressure switch set at 90psi. thanks again, charlie

Response: You are most welcome! Glad to have been at least a little help. The thanks needs to go too, to all the folks that write in with compressor problems and solutions. B.