I have an old air compressor (1970s/1980s vintage) that has recently started tripping the circuit breaker that it is on. I hooked up a clamp meter and found that when the compressor motor is running with no load (belt removed) it is drawing 12 amps and when the belt is in place it is drawing 27 amps.
The motor is a 1hp unit with a listed FLA of just over 17 amps @ 120v. I've checked for any loose connections as well as looked it over with a thermal camera while it's running and see nothing that stands out as obviously abnormal.
The motor can be wired for either 120 or 240 volts, and is currently wired for 120 volts. There are four wires inside of the connection box on the end of the motor.
What would cause such a high current draw and what should I check next?