1. Compressor not turning on
2. Blowing hot air
3. Circuit breaker tripping
4. Outdoor unit vibrates when starting
5. Strange noise

Cabin temperatures higher than normal. One of the first signs that a compressor may be having trouble is the AC no longer blowing as cold as it once did. …
Loud noises when the compressor is running. …
Compressor clutch is not moving.
Should You Replace the System when noticing these?

If your system is old enough, the answer might be yes. Either way, you should have the system looked at by a professional as soon as you notice an issue. Get a thorough recommendation to find out whether it’s worth it to fix the failing A/C compressor or if you’re better off investing in a whole new unit.