Unloader valve is leaking air when the air compressor reaches the normal cut out pressure and stops but you notice while the air compressor is off that air is leaking out of a valve attached to or perhaps inside of the air compressor pressure switch.
Compressor drain valve leaking.
You can try to clean out the old one.
Which i ve never seen done on any compressor tank.
Makita mac700 air compressor.
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The valve on the outside of the pressure switch may look something like the one in the image.
To fix the air leak caused by a faulty drain valve there are three choices.
They usually use a high strength thread locker on the drain valves so it may just be very very hard to remove.
Drain the air tank from the drain valve.
If the check valve is now.
How to fix it.
Product links below in order of appearance.
1 unplug the compressor 2 drain all the air from the tank 3 remove the lines connected to the tank check valve 4 remove the tank check valve inspect clean re install the same one or install a new one 5 reassemble and test the compressor operation.
After cleaning replace the parts.
Remove the regulator body from the manifold with a wrench.
Besides the drain valve is relatively easy and inexpensive to fix.
Clean the regulator 4.
I would recommend replacing the valve and using some thread locker when you install the new one.