The following is from the owner's manual for my Sears Craftsman 3 HP 12 gallon oil-less compressor (model 919.153030 or 919.153130).
Seems to me it might be better to just open the drain valve while running the compressor during break-in, instead of adjusting the regulator. Note that your regulator may not turn the same direction as mine.
Have fun!
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Break-In Procedure
1. Set the pressure switch OFF/AUTO lever to the "OFF" position.
2. Plug the power cord into the correct branch circuit receptable.
3. Turn the regulator clockwise, opening it full, to prevent air pressure build-up in the tank.
4. Move the OFF/AUTO level to "AUTO". The compressor will start.
5. Run the compressor for 15 minutes. Make sure the regulator is open and there is no tank pressure build-up.
6. After 15 minutes, close the regulator by turning it counter-clockwise. The air tank will fill to the cut-out pressure and then the motor will start.
