# Ceiling Fan Capacitor



## A Little Short (Nov 11, 2010)

How do you check a capacitor for a ceiling fan?

Used to you could just pick one up locally, especially at the "Box" 
stores. They weren't very expensive so it wasn't a big deal to just buy one and try it. 
Now I can't seem to find them. Often I find a customer is in love with their fan and just wants it repaired. So how do you go about checking to see if it's the capacitor or not?


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## RIVETER (Sep 26, 2009)

Fluke tester with that capability. Other than that...Grainger's..


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## Semi-Ret Electrician (Nov 10, 2011)

Best, using a DMM if you have a capacitance scale..read the meter.

1) measure the DC resistance and watch it charge up, or read some low value, if it's shorted.
or
2) set your DMM to DC volts and put it across a 9 V battery, watch it charge to near 9 V.

3) replace it with a known good one and watch the fan spin.

Short the leads on a charged capacitor and look for a spark.


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## 8V71 (Dec 23, 2011)

You can check it in circuit with an amp and volt meter. Amps x 2,650 divided by voltage = microfarads.


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## RIVETER (Sep 26, 2009)

8V71 said:


> You can check it in circuit with an amp and volt meter. Amps x 2,650 divided by voltage = microfarads.


Guess I am STILL learning.:no:


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## A Little Short (Nov 11, 2010)

Semi-Ret Electrician said:


> Best, using a DMM if you have a capacitance scale..read the meter.
> 
> 1) measure the DC resistance and watch it charge up, or read some low value, if it's shorted.
> or
> ...





8V71 said:


> You can check it in circuit with an amp and volt meter. Amps x 2,650 divided by voltage = microfarads.


Ok I have 5 leads, fan is 3-speed. Leads are:

(2) orange which I assume are the input. One goes to speed control and the other goes to the directional switch
(1) yellow which goes to the speed control
(1) purple to the speed control
(1) red that goes to the motor

So I should check between either orange lead and one of the other three (red, yellow, or purple)?


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## bkmichael65 (Mar 25, 2013)

Check between orange and the two leads that go to your speed control. Lowest cap value is low speed, higher is medium and the two in parallel are high speed.



Edit- I think that's right. It's been years since I messed with ceiling fans


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## rookie sparky (Nov 6, 2014)

Resistance reading on an analog meter works too. Not as precise as a meter with capacitance, but if the needle swings all the way over to infinity, the slowly drops back as the capacitor charges, it's working fine.


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## 8V71 (Dec 23, 2011)

A Little Short said:


> Ok I have 5 leads, fan is 3-speed. Leads are:
> 
> (2) orange which I assume are the input. One goes to speed control and the other goes to the directional switch
> (1) yellow which goes to the speed control
> ...


To be honest I'm not familiar with the colors but I can give you general information. On a simple non-electronic speed control the 3 capacitors limit voltage and current to the run winding. The higher the cap value the faster the fan will run.

If a fan is humming but not turning chances are the problem is in the speed control section or the run winding is burned up but you should be able to smell that. I would only suspect a bad cap if the fan is missing a speed or two because it would be rare for all of them to fail.

The formula that I mentioned will not work if you have an open run winding. It would not work if the cap is shorted but the run winding would probably be burnt up as well. The voltage in the formula is meant to be taken across the 2 leads of the capacitor, so use whatever wires that will make that happen or go directly across the cap if you have access to it. So basically the formula (or capacitance meter) is good for checking the value of caps but I would use a multimeter and amp clamp for troubleshooting.


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## A Little Short (Nov 11, 2010)

8V71 said:


> To be honest I'm not familiar with the colors but I can give you general information. On a simple non-electronic speed control the 3 capacitors limit voltage and current to the run winding. The higher the cap value the faster the fan will run.
> 
> If a fan is humming but not turning chances are the problem is in the speed control section or the run winding is burned up but you should be able to smell that. I would only suspect a bad cap if the fan is missing a speed or two because it would be rare for all of them to fail.
> 
> The formula that I mentioned will not work if you have an open run winding. It would not work if the cap is shorted but the run winding would probably be burnt up as well. The voltage in the formula is meant to be taken across the 2 leads of the capacitor, so use whatever wires that will make that happen or go directly across the cap if you have access to it. So basically the formula (or capacitance meter) is good for checking the value of caps but I would use a multimeter and amp clamp for troubleshooting.


Although all in info everyone has given me will help in the future, turns out I don't need it in this instance.

I found the hot lead to the fan motor was burnt/rubbed through. The leads were left too long and were rubbing against the fan housing. Over time it rubbed enough to cause it to arc and burn through. It was hard to see on the black wire. Only reason I did find it was I saw tiny burn marks around the housing.

I only suspected the capacitor or something in the motor because the light worked but not the fan. I should have realized that probably would only have lost a speed or two if it was the cap.
Thanks!


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## Dennis Alwon (May 9, 2009)

Good job Bill. My guys would probably test for power at the ceiling and then say they need a new fan. I would be tempted to do the same after a quick investigation.


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## LGLS (Nov 10, 2007)

Dennis Alwon said:


> Good job Bill. My guys would probably test for power at the ceiling and then say they need a new fan. I would be tempted to do the same after a quick investigation.


Which is exactly what should have happened. Since when is it the job of an electrician to diagnose and repair utilization equipment? And in this case, if the fan repair doesn't outlive the customer's memory, the fans next failure will be your fault.


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## Big John (May 23, 2010)

Good gravy, we ain't talking about rewinding the motor by hand on the customers coffee-table. He found a short in a hot conductor and patched it up. Next job.


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## Semi-Ret Electrician (Nov 10, 2011)

We build our reputations with customers based on results.

While our responsibility may end at a connector explaining that to a client and saying you will try to help them if they understand it's "above and beyond" your job description, insurance coverage, training etc. and they will not hold you or your company responsible if things don't turn out well.

I understand what Island Guy is saying - I've had it backfire on me also.
I found a bad photocell on a really old area light. Told the HO I wasn't there to fix the light, which should be replaced, but would give her a new photocell if she didn't hold me responsible. I even noted same on my invoice.

Short ending..it failed, I was called back and the HO expected a free fix.


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## bkmichael65 (Mar 25, 2013)

IslandGuy said:


> Which is exactly what should have happened. Since when is it the job of an electrician to diagnose and repair utilization equipment? And in this case, if the fan repair doesn't outlive the customer's memory, the fans next failure will be your fault.


I'm not sure how replacing a burnt lead on a piece of equipment is outside the scope of an electrician.


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## A Little Short (Nov 11, 2010)

Big John said:


> Good gravy, we ain't talking about rewinding the motor by hand on the customers coffee-table. * He found a short *in a hot conductor and patched it up. Next job.


Well, that is my forum name!:jester:


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## dronai (Apr 11, 2011)

Guys, while were on the subject of Capacitors. I just replaced a Metal Halide wallpack ballast with a new kit.

The old stuff looked new still, but after I replaced, the light worked. I tested the ballast from each tap to common, and had continuity. I tested each tap to ground and nothing. I also bench tested hot, and it hums like a MH ballast does. Customer paid done deal.



I suspect it just the capacitor. It's a 15 uf cap, but my meter reads .31 nf ? and .23 nf with nothing on the leads ! 15uf = 15000 nf

Meter is a Klein CL3000 shouldn't it zero out ?


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## Big John (May 23, 2010)

Eh, my first answer is "What do you expect from a Klein?" but a more serious note, _maybe_ you've got normal capacitance between the leads. Unplug the leads, your capacitance value should read OL. If it don't, well, what do you expect from a Klein? :whistling2:


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## dronai (Apr 11, 2011)

Big John said:


> Eh, my first answer is "What do you expect from a Klein?" but a more serious note, _maybe_ you've got normal capacitance between the leads. Unplug the leads, your capacitance value should read OL. If it don't, well, what do you expect from a Klein? :whistling2:


 Yeah, I tested the meter on known values on electronics caps, and it's all messed up ! Brand new too ! No it does not zero out


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## PenncoStudentDre (Dec 18, 2014)

*My opinion*

You should just check for current going through the capacitor by putting your ammeter in circuit. If no current then its dead.:jester:


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## bobelectric (Feb 24, 2007)

bkmichael65;1372755
Edit- I think that's right. It's been years since I messed with ceiling fans[/quote said:


> Lucky! I still get sucked into doing them. *Gas Money.*


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