Try to turn the compressor by hand. It should be possible to turn it around. It should turn around smoothly, without any ‘hiccups’ (be sure to completely shut down the air compressor!). Check the isolation of the motor winding.
[pdf] The quickest way for direct results is to get my Air Compressor Troubleshooting Guide. You press the start button but nothing happens. Either an electrical problem, or the compressor has tripped on a safety device. Check supply power. Check for errors on display. Check emergency stop is out.
[pdf] If your compressor is experiencing loading or unloading issues, check the electrical components, such as the solenoid valves, and inspect mechanical components like the air filter, intake valve, and pressure switch.
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