Fan makes a strange noise


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Old 09-02-23, 06:47 AM
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Fan makes a strange noise

My outside Goodman house AC unit makes weird noises when the fan is running. My guess is either run cap or fan motor. I tested the run capacitor rated 65/5 uf. My readings show 60 and 3.7. Clearly both are a bit off the rated values. The cap looks good no leaks or bulging etc. Could this cause the fan to make these noises or should I proceed with testing the motor ? Many thanks
 
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Old 09-02-23, 07:00 AM
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Capacitors almost always have a pretty wide tolerance range so it's unlikely a problem with the cap.

Most likely it's the condenser fan motor's shaft bushing making the strange noise. Maybe the fan motor is about worn out and it's time to replace it.
 
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Old 09-02-23, 08:07 AM
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"Weird noise" really doesn't tell us anything. What type of noise is it? Humming, clicking, rattling, buzzing, grinding, metal on metal scraping...

Where is the sound coming from? Is it coming from the fan or it's motor? Is it coming from the compressor or something in the controls area?
 
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Old 09-02-23, 10:56 AM
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I have a short video showing the fan running with the noise, but I am unable to attach it here. The noise is very regular and sounds like a grinding noise.
 
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Old 09-02-23, 11:51 AM
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You need to upload it to YouTube then post the link here.
 
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Old 09-02-23, 02:09 PM
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It sounds like a defective motor bearing. No way to oil them effectively.
Usually requires motor replacement.
 
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Old 09-02-23, 03:39 PM
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Thank you guys so much ! Iíll replace the motor and update you.
 
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Old 09-02-23, 03:48 PM
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Be sure to replace to replace the capacitor too.
It may or not be the same value.
 
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Old 09-02-23, 06:08 PM
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Are you referring to the run cap ? Or, does the condenser motor have its own capacitor ?
 
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Old 09-02-23, 06:20 PM
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There is a compressor cap and a fan cap or a combo dual cap.

Sometimes when replacing the fan motor and new single cap is connected regardless if the existing is a dual cap.
 
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Old 09-09-23, 10:36 PM
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So I replaced the original 3 wire motor with a universal motor with same RPM and horse power. The replacement motor has 4 wires. I capped off the white wire since it is the same as the white and brown wire. I connected white and brown wire to FAN on the also new dual capacitor. I connected purple wire from motor to C on capacitor, and I connected black wire to power side. The replacement motor has a green ground wire which I screwed to the AC unit metal cover. Now the unit seems to work as it should when I turn it on but the metal cover of the unit gets very hot. I believe it is because the motor heats up a lot. I donít think this is normal but I turned the unit off right away. Is it possible this has to do with grounding the green wire ?
 
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Old 09-10-23, 02:12 PM
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Normally when a motor gets replaced.... it's running amperage is checked to make sure it's within motor rating. Did you verify that the required new motor capacitor size is the same as the one you currently have ?

Nothing to do with ground wire.
 
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Old 09-10-23, 04:34 PM
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Iíll run some more testing and post back. Yes, the cap is exactly the same. I even measured it with a cap meter just to be sure. Values are on the money 60/5. Advice to the wise : if the difference in price is small between a universal and OEM motor, go with OEM ! I had to do a few things to this motor to make it fit. The threaded 4 legs were too long. I had to screw them back and then cut off the other ends so they donít hit the fan. The motor shaft is longer than the original and Iím debating if I should cut it off to same length as the original.
 
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Old 09-10-23, 04:42 PM
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Universal motors can require modifications.
You can cut the shaft if it's going to hit something.

Make sure fan is on the shaft so that it's located in the fan opening properly.
 
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Old 09-10-23, 07:20 PM
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Make sure the motor is spinning the fan the correct way! Seriously!

The fan should be properly positioned in its shroud, typically with 1/3 of the blades above the shroud and 2/3 below. This should cup the air and push it out the top.

 
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Old 09-13-23, 07:42 AM
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Problem solved !! A BIG thank you to all the professionals here who responded and helped with their valuable advice. The motor current draw was fine. But the outside would get very hot in two minutes. The problem was the fan. For some reason, this motor was designed to spin the fan clockwise. In my case, that would pull air down inside the unit instead of out. I followed some tips and switched the two motor wires to the cap. I placed the purple wire on fan terminal and brown wire on C terminal. Fan started spinning counter clockwise and moving air out. No more noises. No more heat. Only beautiful cold air is blowing in my house
 
 

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