Air Compressor won't fill past 52 psi!?

Question

I have an 8 gallon Central Pneumatic air compressor. Recently it started running continuously. When I checked it I noticed that it wasn't building pressure past 52 psi, though the motor never switched off. The tank will hold the 52 psi indefinitely so it is not leaking. I let it run for 30 mins. two days ago and it still did not fill past 52 psi. What could be causing this?

Answer 1

There are two adjustment screws inside of your air compressor switch, one turns the pump on below the set pressure, the other turns it off when the high pressure setting is reached, it sounds as if your high pressure switch is bad, you can sometimes clean them up with emory cloth.  The screws can be adjusted, be sure that you unplug the unit first as these are very near the electrical contacts.

Do a few things before this.  Make sure that you drain the tank completely of water, I've seen compressor tanks half full of water, this not only effects the compressor performance but also the life of the tools attached to it.  The other thing that you should check is that the relief valve is working properly.  It should pop off at a preset pressure to ensure that the tank doesn't become over pressurized.   You should also check to see that all fittings are sealed with teflon tape or pipe dope, including the tank to switch and the little tube that runs back to the switch.  Good Luck on fixing your problem.

Answer 2

The valves in the compressor are leaking by.

You would find them in the head of the compressor.

Probably reed valves.