Question about Hitachi EC12 Portable Electric 2hp Air Compressor, Oil Lubricated

1 Answer

Compressor builds pressure, but does not shut off

My compressor will operate just fine, I just have to babysit it and shut it down when it gets fully pressurized, if not, the pressure will go through the roof. The auto shut-off and start up are not working.

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  • twistedgrip Feb 10, 2009

    I'm not sure how and where to adjust that.

  • robert sanko May 11, 2010

    When you say the auto switch isn't working have you tried adjusting the cut-in/cut-out inside of the controller?


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  • 1,378 Answers

Hitachi builds a very nice compressor, however suffers from the same problem that all brands will eventually encounter. Failure of the pressure switch. The pressure switch is a very hard working component of the unit. Depending on use, the pressure switch may cycle from as little as two or three cycles a day to as many as dozens per hour. The pressure switch has springs, contacts and unloader features that eventually wear out. The two most common failures are the contacts and the rubber diaphragm that acts against the springs to shut the unit down. Sometimes the screws securing the base of the switch the inlet port come loose and cause the problem that you are having. (The rubber diaphragm is between the base inlet port and the switch) Simple test is to spray soapy water around base of switch to check for leaks. Replace the switch as necessary with a SquareD brand available at instead of factory unit to save money and increase life. You may have to make simple modifications however the money saved will be worth it. Choose a pressure switch with cut-off range between 120-139 psi. The higher the cutout switch setting you choose the shorter lifespan for your compressor. Your compressor works harder and gets hotter when achieving higher pressures. Try to use either no extension or shortest cord possible to max life of unit and compressor oil instead of motor oil to prevent carbon deposits. Good luck and email if you have questions about your Hitachi.

Posted on Feb 11, 2009

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