Hi, I think that you have 2 problems here.
The lower voltage is more a bit of a problem because at the lower voltage the motor hasn't got all the torque available to start into the load.
It may stall and humm and eventually burn out or get very hot till the insulation fails at some stage.
Check with the nameplate as the higher frequency has the motor run at a higher speed and the compressor may not be designed for it. e.g. a 1500 RPM motor at 50 Hz will run at 1800 RPM at 60 Hz and may cause the compressor to run hotter.
good luck Ray
