Check the motor nameplate first to see if they are rated for 50/60. The main problem with running refrigerant compressors at abnormal speeds is that it changes the compression ratio drastically. This leads to lubrication problems and major differences in the design performance of the system.
Also check the units for control circuit transformers. If the unit has them to drop the 220 down to 115 or 24 volts you may have a problem with the voltage on the secondary dropping too low. Some devices will not operate if the control power drops too far. We have certain digital controllers that will simply deactivate themselves rather than run on errant voltage.
You might try to contact the Orignal Equipment Manufacturer and ask them to run a balance on these units at 208/50 and see if it should run on that and what effects that operating voltage and hertz will have on your performance.
