I think refrigerator compressor motors are single-phase motors. It’s cheap, and it can run right off the mains single-phase supply.
But single-phase motors don’t start very well - depending on what the position the motor is in, it might start rotating in the wrong direction for the pump to work; or it might just sit there, oscillating, not generating enough torque to even make the first rotation.
So most single-phase motors actually start with two-phases, the second phase helping give the rotor the torque vector it needs to start spinning in the right direction.
Once the motor is spi