Tag: fan motor

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.

In this 60-second tech tip video by Brad Hicks with HVAC in SC. he shows us how and why to remove the weep port plugs on a condensing fan motor. I know from experience that motors can fail prematurely when this practice isn’t followed. Remember that motor orientation dictates which are removed. It (generally) the ports facing down that need to be removed and the ones face up stay in place.

Transcript

What’s going on guys here is a quick 60-second tech tip is on changing condenser fan motors. Whenever you’re changing them, most all condenser fan motors have plugs that are supposed to be removed depending on the orientation of the motor. Since this shaft is facing down into the unit these need to be removed and basically what they do is, they open the weep holes so any condensation or moisture that can get into the motor doesn’t stay in there to corrode the windings and in turn prematurely make the motor fail. So make sure you take those plugs out, if you don’t, like that motor over there you’ll be back within a couple years to replace it again. Just a quick tip make sure you take those plugs out like I said this motor is oriented this way so you want to take the plugs out of the bottom like I just did and your motor will last much longer. There you go thanks for watching.
— Brad Hicks

 

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