How can you tell if your ac compressor is really locked up?

To determine if your AC compressor is locked up, listen for unusual noises like grinding or clunking when the system is running. You can also check for signs of overheating or if the compressor is excessively hot to the touch. Additionally, if the compressor's clutch isn't engaging, this might indicate a lock-up. Finally, a lack of cold air from the vents despite the system being on can also suggest a problem with the compressor.