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3-Wire and 4-Wire Condensing Fan Motor Connection

This tech tip 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, but it's actually very simple once you see it. Now, keep in mind that wire colors ACTUALLY MEAN NOTHING, but the colors tend to be consistent on service replacement motors. 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 the 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 the 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.

As you can see, the only difference is that there is no jumper from the contactor to the capacitor. That is because the brown + white and the white are 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 ohmmeter 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.

P.S. – If you would like to understand 3- or 4-wire connections within the entire process of replacing a condenser fan, please check out this article.

Work through this with the trade.

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Comments

Kent Jones
Kent Jones @bryanorr

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.

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9/30/17 at 12:49 PM

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.

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Joe Valentino
Joe Valentino @bryanorr

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

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10/1/17 at 04:53 AM

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

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philip
philip @bryanorr

I often use and recommend the three wire connection when wiring to a dual cap

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3/16/21 at 06:32 PM

I often use and recommend the three wire connection when wiring to a dual cap

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Mo
Mo @bryanorr

Thanks for posting! This is great!

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5/6/21 at 08:59 PM

Thanks for posting! This is great!

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Serena Willis
Serena Willis @bryanorr

ya looks good .

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6/29/21 at 02:12 PM

ya looks good .

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