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Will a fan run with its capacitor?


Dennis Long
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I'm testing an Emerson pedestal fan I bought yesterday. The fan won't run unless I move the speed switch to 'high', and then it only budges about an inch. So, current seems to be reaching the motor in some capacity.

Is it ok to remove a capacitor from a fan and join the 2 leads together if all I'm trying to do is test the motor/switch for functionality?  Isn't the capacitor's function to store up enough power just to get the fan started?  The capacitor looks original and I suspect it's bad.

Edited by Dennis Long
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Could one of the administrators change the word "with" to "without" in the thread title? Or, is that something I'm supposed to be able to do? Thanks.

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11 minutes ago, Steve Sherwood said:

I don't think it will run without the capacitor.

Thanks Steve, you're right. I happened to find a spare capacitor, hooked it up, and the motor works, although I still had to kick-start it. But it ran - I'll have to compare ratings to the original capacitor.

Then, just for the heck of it, I directly connected the leads that go to the capacitor and it wouldn't run, even with a kick-start.

Learned something today............

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I had a similar issue recently with two Hunter (GE) BMY fans; the start coils in both were non-functional, so the fan wouldn’t spin up without a push start.  I was able to get both to run by connecting two of the head wires directly to a power cord and pushing the blades to get them going.  Once I got the proper capacitor, the one fan I put back together would start on its own. 

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Turns out my old capacitor is rated at 3.75 microfarads, 330 V, 60 cycles.  Will a 4 microfarad, 450V, 60 cycles capacitor work? Based on my readings, it would seem so, but wanted to ask before I ordered the cap.

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1 hour ago, Dennis Long said:

Turns out my old capacitor is rated at 3.75 microfarads, 330 V, 60 cycles.  Will a 4 microfarad, 450V, 60 cycles capacitor work? Based on my readings, it would seem so, but wanted to ask before I ordered the cap.

Yes. 

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You’re better off with one with a slightly smaller mfd value. The size you mentioned will be ok for testing however. Long term it might cause the motor to get hotter than normal 

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That is what I have Andrew, never run into a 3.75 unless it is a Deacon motor.

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On 9/1/2023 at 11:55 AM, Stan Adams said:

Dennis, you said Emerson pedestal. Is it a K60 & if so, what size?

Stan, this fan's data plate is a bit messed up (see picture below). The data plate seems to say 77648-AP, even though I was expecting to see 77646 since, as you can see in my picture below, it's a 12" fan. It's a bullet back with the krinkle paint. The cord was cut, but I hooked it up and all 3 speeds work, once I push-started the fan with my "test" capacitor.

I'm a little confused that the fan is a 12", since the data plate seems to say 77648 and it has the larger capacitor. I had the thought that maybe the fan was a 77648 originally, but the blade and cage were replaced with 12" blades and cage?  Are those interchangeable?

Brandon has one of these at his house 30 minutes away, but he's out of town. I will be going to his house later this week to do something for him, so I plan to remove the bottom plate and check his capacitor specs since his works perfect. I was planning to buy whatever his fan uses, but what if my motor was a 77648?  He also has a 77648 pedestal, so I might check that one too.

Data Plate.jpg

Cage.jpg

Full Size.jpg

Edited by Dennis Long
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On 9/1/2023 at 11:57 AM, Andrew Block said:

What size fan is this? The 16” uses a 2.5mfd and the 24” uses a 5. 

Andrew, see my response to Stan above. Thanks.

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Well Dennis this is a strange character. Yes that model number is a 16" motor, leads me to believe it got kicked over & someone put a different blade & cage on it. That cap still has me scratching my head though. A 77648 normally takes a 2.5 MFD.

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20 minutes ago, Stan Adams said:

........ A 77648 normally takes a 2.5 MFD.

So, do you think having the smaller 12" blades would call for something a little smaller than the 2.5MFD, or would you just go with the 2.5 if it were you?  I'm still going to check Brandon's fans' caps before I buy.

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