Troubleshooting an air compressor depends on the exact problem of the compressor. Common air compressor problems include faulty electrical system, as well as oil and air leaks.
To fix the electrical system, plug in the compressor if it's unplugged, and turn it on. If the compressor fails to turn on, locate and press the reset button usually located at the back of the motor casing. If the compressor still fails to turn on, unplug it and test the outlet for power by plugging in another electronic. If the electronic fails to work, repair the power supply system. If it works, seek the services of a professional to fix the internal problems of the compressor.
Air leakage can either occur at the compressor's fittings or in its tank. To troubleshoot the leaking fittings, detach the tools and hoses, switch on and allow the compressor to charge. Saturate the fittings with soapy water, and check them for bubbles. If bubbles appear, release the pressure by pulling the stop valve, wrench out the fittings that show bubbles, wrap plumber's tape around them, and replace the fittings. For tank air leaks, spray the tank with soapy water, check it for bubbles, and replace the tank with a new one if the bubbles appear.
To repair oil leaks, disconnect the compressor, allow the engine to cool, and check the oil level and cleanliness, and if it's the right oil. If needed, replace the oil, tighten or replace the gaskets, and unblock or replace any damaged hoses.