40400 Compressor Hums

by Richard
(Falls Church, VA)

My 40400 hums when turned on. I opened the shroud looking for the reset switch and could not find it. However, the fan blades will difficult to rotate.


I have reviewed the trouble shooting section on this forum and cannot find my problem and the solution. Any thoughts?

Also, it is possible the compressor ran with no oil by the previous owner.

Cooper

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What capacitor for a 40440?

by alan
(texas)

What size needed to be compatible?

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intermittent issue with shut-off

by Booten
(St. Louis, MO.)

I run my compressor with the regulator set at about 100 pounds to supply air to a pneumatic framing nailer. The automatic shut-off will sometimes work when the compressor reaches 100 pounds and other times the relief valve blows. What am I missing?

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The overload protection has to be reset frequently to build pressure

by James Waldron
(Pierre Part, LA USA)

The overload protection button has to be reset frequently to build pressure. It will run for approximately 10 to 15 seconds and shutdown. I can reset and the unit will run again. The pressure will increase approximately 10 PSI each time I reset. The oil level is good. The motor does not feal or bind when rotated by hand.

This unit was given to me because of this problem. I do not know how this unit has been handled or maintained.

Can you give me any suggestions of things to check or parts you think could give me this problem?

Thanks,

James Waldron
__________________
Hi James. If by "overload protection button " you mean the thermal cut out that protects the motor, it is popping, presumably, because the motor is overheating.

By resetting so frequently, you are quite likely harming the motor.

You don't indicate in your post how your air compressor is powered? By that, I mean, are you using an extension cord or power bar into which you plug the compressor cord? If so, stop!

You need clean power to run an air compressor effectively, and that means if not a dedicated plug of, preferably, a 20 amp circuit, at least one that has no other applicances pulling power from the same circuit as the compressor is trying to run.

If the power supply is good, then I would next suspect the start / run capacitor is failing.

There is a page on this site explaining how to test a capacitor.

Cheers,

Bill

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