Does your compressor start up hard after it has been running?
Is there a constant hissing from the unloader valve?
Do the belts squeal on a restart?
Do the breakers trip while the compressor is running?
These are all symptoms of a bad check valve.
The check valve is usually located between the discharge line and the tank. This valve keeps the compressed air in the tank and lets the compressor do its job. When this valve goes bad, and they all will, damage can happen to your compressor or your motor quickly.
If this sounds like something going on with your machine, call us at 1-864-877-3515, and we can walk you through this problem.