AC System Noisy

PROBLEM: Indoor AC fan making noise during operation [high pitch].
FIX: Replaced fan. Cost=$400.00
Wife complained that the AC fan was making an abnormal noise, I ignored the client for a few days but then the noise became louder. I contacted an AC service and diagnosed the problem without even doing any troubleshooting. [I guess this is a known issue]. No, the AC does not need to be replaced as some AC guys will tell you. It’s been 3 months now and everything is working fine.