I shipped/installed US fans (120v @60hz) in Montego Bay, Jamaica. Jamaica uses 12v @50 hz). Though the fans work they make lot of noise like they are laboring/straining to turn. Is there any fix (preferably inexpensive) other than replacing the fan motors.
Can you recommens a manufacturer that makes 120v @ 50hz fans
No real easy fix. While 50Hz equipment can pretty much always run on 60Hz, the opposite is not true. The fans are experiencing "saturation", where the magnetic field in the motor is too high because the frequency is too low for the voltage. Aside from using a 60Hz fan motor, the only good solution would be to use a transformer to drop the voltage down to about 100V. This will bring the volts/Hz ratio back to where it should be and prevent saturation. The fans won't turn very fast, though.