3 or 4 Wire? Condenser Fan Motor Wiring

    I wanted to give a visual of why there are motors that can be wired as 3 wire or 4 wire applications. It is not as mind-twisting as it seems once you can see it laid out visually. So here are 2 diagrams of a condenser fan motor wired first in a 4 wire configuration and next as a 3 wire configuration.

    As you will see, the "white" wire and the "brown/white" wire are connected internally and are really the same input into the main winding and capacitor.

NOTE: Please don't be confused by OEM wire colors. Wire colors actually mean nothing, but are "usually" consistent on service replacements motors.

    If the original OEM configuration was a 4 wire configuration, then there is no jumper wire going from the contactor to the capacitor. Power travels from the contactor to the main winding through the "white" wire and on to the capacitor through the "brown/white" wire. The "white" and "brown/white" are joined internally inside the motor.

    If the original OEM configuration was a 3 wire configuration, then there is a jumper wire going from the contactor to the capacitor. Power travels from the contactor to the capacitor through the jumper and on to the main winding through the "white" wire. The 2 wires are joined at the capacitor terminal. So the "brown/white" is not necessary, and is therefore capped off.

    You can test this by ohming between the "white" wire and the "brown/white" wire. You will see there are zero ohms or very low ohms (1 ohm or less typically) between them. This is because they are essential the same wire.