furnace fan motor start capacitor

[osu69]

Need some advice on selecting the proper start capacitor for a 120v, 1/3HP motor. Similar motors listed on Amazon call for 5mfd, 377v capacitor; the existing fan motor has a 6mfd, 377v capacitor. The fan motor in my auto shop has a 14mfd capacitor.

Is the difference significant? Is there a range of capacitance that's acceptable?

I'm clueless on this one and need some direction.

 

[Super Scout]

You can go higher. You cannot go lower. I am a little confused as to what your fan motor has now, 6 or 14 ? If its 6, you can 7,8,9. 14 you can go higher as well.

 

[osu69]

I bought a new motor (1/3HP, 120v) and it didn't come with a capacitor-so I'm trying to find one. I'm not sure what value to buy and it appears there's a wide range of values that work with a 1/3HP motor...

 

[Bob C]

It really depends on the design of the motor. Some motors are split phase and do not require a cap. For your original question, yes you can go a bit higher. On the original capacitor, you will see a tolerance like +- 5%. That is the window you can choose from to stay within the designed specification of the motor. Always keep the voltage the same or higher. If a cap calls for 6MFD 377 Volt, either replace with same or for example go to 6MFD 450 Volt. Any electrc motor shop should be able to sell you a cap.

 

[Super Scout]

I would call an electric motor shop, you may not need a capacitor at all on the new motor.