3 wire and 4 wire Condensing Fan Motor Connection

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Diagram courtesy of Emerson

How to wire a condensing fan motor for 3 vs. 4 wires is a common question by new techs. Jesse Grandbois submitted this tech tip to help make it simple. Thanks Jesse!.


This is a quick one on the difference between wiring universal condenser fan motors and why brown+white is the same wire as white. This one seems to confuse even experienced technicians and really is very simple once you see it. Now keep in mind that wire colors ACTUALLY MEAN NOTHING, but on service replacement motors the colors do tend to be consistent. As always, refer to the wiring diagram on the particular motor you are using.

I’ll provide a diagram and explain the wires below.

Here’s the 3 wire method:
– White wire from the condenser fan motor to one side of power on the contactor (T1) and jumped to one side of the fan capacitor. This is AC power and not a dual capacitor, so the terminal side does not matter
– Black wire from the condenser fan motor to other side of power on the contactor (T2)
– Brown wire from the condenser fan motor to the other side of the capacitor opposite the jumper wire.
– Cap off brown+white (unused)

Now for your 4 wire method:
– White wire from the condenser fan motor to one side of power on the contactor (T1)
– Black wire from the condenser fan motor to other side of power on the contactor (T2)
– Brown wire from the condenser fan motor to the capacitor. Again, this is AC power and not a dual capacitor, so the terminal side does not matter
– Brown+white wire to the other side of the capacitor

Now as you can see the only difference is there is no jumper from the contactor to the capacitor. This is because the brown+white and the white is the same wire. They’re joined inside the motor. The brown wire with the white stripe is only there for convenience.

If you want to prove that the white and brown w/ white stripe are the same, take an ohm meter and test between the two. You will find that it either reads Zero or very low ohms proving that they are directly connected within the motor.

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5 comments

  1. Kent Jones says:

    Usually choose the 4 wire method and have always trained guys that way. Is there a difference in operation between methods? It’s always been my understanding that it doesn’t make a difference. I teach the four wire method because it is impossible to get confused.

    1. Jesse says:

      In my opinion it would make no performance difference. I don’t see how it could.

  2. Joe Valentino says:

    Good morning,
    You can also just jump common from original cap. Correct?

    1. Jesse says:

      That’s the 3 wire method you’re talking about like this http://i.imgur.com/Yk5JRdn.png (which is the same as http://i.imgur.com/C06Hzap.png 4 wire) because the brown+white and the white is the same wire.

      Here’s another diagram I found on google imageshttp://photobucket.com/gallery/http://s151.photobucket.com/user/Houston204/media/MotorWiring.jpg.html

      1. Joe Valentino says:

        Yes, my comment was for the 3 wire & what I was saying was instead of jumping from the starter/contactor you can also jump common direct from the cap.

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