Bryan explains the difference between 3-wire and 4-wire condenser fan motor wiring configurations. The differences between 3-wire and 4-wire configurations are especially important when you're replacing an OEM condenser fan motor with an aftermarket condenser fan motor.
The main difference between the two wiring configurations lies in the utilization of the brown-and-white wire. The 4-wire configuration uses the brown wire as the capacitor lead and the brown-and-white wire as the capacitor common. Those two wires are actually the same; the brown-and-white wire is an automatic jumper with the actual connection inside the motor.
In many cases, you're also replacing the factory or OEM capacitor with a universal dual capacitor. In those cases, you can use the 3-wire configuration by cutting the brown-and-white wire back at the motor and putting a wire nut on it or running it into the cabinet and capping it there. The three-wire configuration requires you to run a jumper from the white wire to the other side of the capacitor.
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