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

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Air compressor problem

My Hitachi EC12 builds air presure the motor stops then the pin valve behind the control that is conected by small air line to the tank check valve begins to bleed off air till the compressor starts again. It is no stop, I changed the control and still have the same problem.

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  • Anonymous Mar 13, 2014

    Small valve on my compressor leaks air once it's full it stops but compressor gets really hot



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  • 135 Answers

Cheap oil-less compressor, normal.
If you don't like it, buy one that uses oil and a drive belt.

Posted on Oct 07, 2008


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1 Answer

My EC12 will start up and hold air, after use the unit will not recycle on. Is this the regulator?

No, this would be the pressure switch. One pipe or small line to the tank, with power cord coming in and cord to motor. It is adjustable so try reducing tension on the spring first. If still no change replace pressure switch.

Dec 07, 2011 | Hitachi EC12 Portable Electric 2hp Air...

1 Answer

Air leaking out the top..not building any pressure

Sounds like theres either a piece of debris in your pressure switch where the 1/4" line enters it. Or you have debris stuck in your check valve or a bad check valve. Remove the pressure switch line and check valve and try cleaning the valve and the switch where the line was disconnected. with solvent and compressed air. Unfortunitely you'll need someone elses air source.

Aug 08, 2010 | Hitachi EC12 Portable Electric 2hp Air...

1 Answer

After my Hitachi ec12 compressor pumps to maximum pressure it shuts off and immediately starts dumping air out of the part name "Joint" which is item 60 in the parts list. It will dump until the motor...

The problem that you describe is most likely the in-tank check valve (brass or chrome valve where air enters tank ). Easy to check. Run compressor till you have about 60-80 lbs in tank then shut-off / unplug for safety. Remove the small hose (1/4) at the check valve and verify that air is leaking from valve. If leaking remove cap from checkvalve and look at inner plastic valve for cracks. Replace as needed then re-test for leaks. You can be creative in making the inner plastic valve (teflon or nylon ball 1/2 - 5/8 ) or replace the whole valve. (inner part not sold separately) Good luck with your repair and post again if you have a question.

Jun 24, 2010 | Hitachi EC12 Portable Electric 2hp Air...

1 Answer

My Hitachi EC12 builds pressure, shuts off, then air escapes

I have the same compressor with the same problem. I have temporarily eliminated the thermal reset with a piece of 12 gauge hard wire and it runs just fine. However, I do want to replace it before the warm weather come to the north. I tested the draw at 15.5 amps and the reset was a 17 amp. I am told by someone with superior electrical background that I need to install a 20 amp thermal reset in it's place. I have found that mine runs best when plugged directly into a 20 amp circuit and when using an extention cord I have a 10 guage cord that will carry the load needed to run the EC12. I have also changed to 100% synthetic oil.

May 15, 2010 | Hitachi EC12 Portable Electric 2hp Air...

3 Answers

My Hitachi EC12 builds pressure, shuts off, then air escapes through the relief valve for a period of time, sometimes shorter sometimes longer. If longer, the compressor switches on again, but has trouble...

the problem is in the check valve where air enters the tank.when leaking it lets air pressure up to the air piston causing the motor to stall upon restart.replace check valve.average cost of part 15 to 30 dollars.simple fix

Mar 29, 2010 | Hitachi EC12 Portable Electric 2hp Air...

5 Answers

I have a Hitachi compressor EC12. Sometimes when

you may have some water build up pull the cover apart look at yor pistons for build up

Jan 07, 2010 | Hitachi EC12 Portable Electric 2hp Air...

1 Answer

Ec12 hitachi air compressor will not build pressure higher than 40psi

most likely the the reed valves are stuck or miss aligned. Worse case senerio your piston seal blew causing this not to build pressure. Read manual on how to disassemble head. to remove should be 4 bolts and your copper line, just be careful of the reed valve plates, they are thin steel that sit into the head. Put back the same way you took it apart.

Feb 28, 2009 | Hitachi EC12 Portable Electric 2hp Air...

2 Answers

Hitachi ec12 motor hums after drop in pressue

There should be a pressure switch adjustment under the cover of the switch remove the cover and reset.

Feb 03, 2009 | Hitachi EC12 Portable Electric 2hp Air...

1 Answer

Hitachi EC12 Compressor- weird hum

The burst of air you hear as the compressor shuts off is the cylinder unloading so it will not have to restart against a high pressure load. If the unloader is electrical it would explain the hum that you hear. This could be a normal function.

Aug 24, 2008 | Hitachi EC12 Portable Electric 2hp Air...

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