Obvious Signs:
* The motor is running: This is the most basic check. Is the motor turning? You should hear the motor humming or whirring.
* Pressure is building: Check the pressure gauge. The needle should be rising as the compressor pumps air into the tank. If it remains at zero or doesn't increase, there's a problem.
* You can hear the compressor cycling on and off: Once the tank reaches the set pressure, the compressor should shut off automatically. After a while, as air is used, it should cycle back on again to repressurize the tank. This on/off cycling is a key indicator of proper function.
* Air is coming out when you use a tool: The most definitive test: connect an air tool (like an impact wrench or nail gun) and see if it works.
Subtle Signs (if the above are unclear):
* Feel for vibrations: While running, the compressor should vibrate slightly. A lack of vibration *could* suggest a problem (but could also be a very quiet motor).
* Listen for unusual noises: Clunking, banging, squealing, or other unusual sounds can indicate problems with the motor, pump, or other components.
* Check for leaks: Inspect the hoses and connections for leaks. A significant leak will prevent the tank from building pressure.
If your compressor isn't working, consider these possibilities:
* Power supply: Make sure the compressor is plugged in and the circuit breaker hasn't tripped.
* Low oil (if it's an oil-lubricated compressor): Check the oil level. Low oil can severely damage the pump.
* Pressure switch issues: The pressure switch controls the on/off cycling. A faulty switch might prevent the compressor from starting or stopping correctly.
* Unloading valve problems: The unloading valve allows air to bypass the pump when the tank is full. A faulty valve can cause the compressor to run continuously.
* Pump problems: This is a more serious issue, possibly requiring professional repair.
If you've checked these things and your air compressor still isn't working correctly, it's best to consult a repair manual or a qualified technician.
