This motor start capacitor 40uf is applied to start a single-phase motor
The Capacitor 40uF is widely used for washing machine, air conditioner, cooling fan, refrigerator, water pump, air compressor, bandsaw, saw, pressure washer, generator, HVAC, drill, splitter, grinder, etc.
This 40uF capacitor has no positive and negative poles, it can be wired at will. If the capacitor of your motor and air compressor is burnt out or weak, you need to replace it with a new one.