Can you help me ID this capacitor?

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Old 06-19-15, 12:13 AM
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Can you help me ID this capacitor?

Can somebody help me identify this capacitor? As you can see it does not say how many uF it is.

AC fan stopped running (as I posted a few days ago) but fan starts if I give it a push. So Id like to change the capacitor first? But read on








However I tested the capacitor using my tongue to charge it through a 9V battery and I can feel a brief jolt when charging, and then again when discharging.

I also used a digital multimeter set on 2M resistance to charge the capacitor one way and then reverse (I assumed it was charged when the resistance reached over 2M and the meter went off scale.
Here is how long it took:
C to Herm terminals: 64 seconds
C to Fan terminals: 7 seconds

I have no way of telling if this is correct as I imagine it depends on both the capacitance (which I dont know) and the effective internal resistance of my cheap digital multimeter.

However both tests seem to show that the two sides of the capacitor can hold some charge. Not?

So perhaps the capacitor is not bad. Perhaps its the motor which I noticed has developed a little bit of resistance; but not much really, seems like it should be able to overcome that, even with its initial lower torque, not?

Its from this air conditioning unit.




And here is the schematic. No capacitance mentioned on schematic either.




From the schematic seems like this is a combo start capacitor for the fan and run capacitor for the compressor? Or start capacitor for both? Or run capacitor for both? I dont understand, if someone could explain Id appreciate.

Thanks.
 
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Old 06-19-15, 04:58 AM
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Capacitor Education

That seems to be what you want. Click on the images to enlarge them.
 
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Old 06-19-15, 06:12 AM
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The uF should be listed on the compressor and fan motor.
 
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Old 06-19-15, 09:15 AM
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Many times it can be determined from the make which is Rheem and the model number.
 
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Old 06-19-15, 09:37 AM
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Pulpo: Thank you for the link with the photos. They were very useful.

skaggsje: Yes indeed! The fan motor does say 3 uF capacitor.
I cannot find anything on the compressor though. There is a tag with the model which is "Model CRL3-0350-PFV". I googled the model and "capacitor" and nothing definitive came up, but I'll look again.


I guess there is no way to tell if these are start or run capacitors. I see on the schematic that the compressor motor terminal that is connected to the Herm cap is labelled with an "S". I guess that means the compressor uses a start cap?
I guess it does not matter whether they are start or run caps, so long as I find the same caps and rewire them as I found them.

==============================

There may be a complication though,

...since I now think it's the motor bearings that are bad. I better observed what happens when the unit tries to start: The fan motor turns about 1/2 turn and then it seems to get stuck. If I spray it with WD40 then it starts and seems to run at normal speed.

This looks like the original motor, which would make it 25 years old. I think I'll try to change it today if I can find it locally...
...Then I'd have to find the appropriate cap with the correct compressor sister cap in the same oval package, otherwise I'll have to find a way to put an additional cap for the new fan motor...
 
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Old 06-19-15, 09:42 AM
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You could just use that existing cap for the compressor..... purchase a new fan motor and a single cap in the size that the new motor requires.
 
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Old 06-19-15, 10:08 AM
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You can often tell if the bearings are worn by feeling for side to side movement in the motor shaft.
There is usually noticeable movement if the bearings are bad enough to prevent the motor from starting.
 
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Old 06-20-15, 02:35 AM
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Excellent idea . He has a value for the fan capacitor . And if he has to replace the fan motor , it may require a different value capacitor any way .

But I would buy a 3 mfd capacitor and try it . Inexpensive fix . If it works . If not , he is not out a lot of $$$ .

http://www.grainger.com/product/TITAN-PRO-Motor-Run-Capacitor-30D581?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/30D572_AS01?$smthumb$

God bless
Wyr
 
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Old 06-20-15, 02:43 AM
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Running 2 capacitors is a simple deal .

Take digital photos so you can use them for reference , if needed .

Unplug the wire going to the fan terminal of the dual capacitor . Plug it into one of the two terminals of the new , single capacitor . Either terminal , makes no difference .

Make a new wire with the appropriate crimp on connector on each end . Plug one end to the C - Common terminal of the old capacitor . Plug the other end of the new wire to the other terminal of the new single capacitor . Mount the new capacitor securely . Put it all back together , turn the power on & give it a try .

Best of luck , :-)

God bless
Wyr
 
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Old 06-20-15, 03:18 AM
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I have found a little information that indicates the compressor uses a 440 VAC capacitor . Either 40 mfd or 45 mfd . There is a little confusion , conflicting information .

God bless
Wyr

PS

https://opi.emersonclimate.com/was.e...web/OPIServlet

This indicates 40 mfd .

TITAN PRO Motor Run Capacitor,40 MFD,4-9/16 In. H - Capacitors - 30D585|TOCF40 - Grainger Industrial Supply

or a dual capacitor

ProductFinder-CapacitorMatch
 
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Old 06-20-15, 06:49 AM
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The voltage rating of the capacitor has no effect on it's motor starting function.
It is the capacitor's ability to withstand the voltage spike that occurs when it discharges.
440 volts is normally the highest rating readily available and is good to use if it will fit.
 
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Old 06-20-15, 06:58 AM
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Very true .

Best I remember , some A/C capacitors are rated 370 VAC , I think . Electrically , the higher voltage rating hurts nothing .

My 4 ton condenser unit had a dual capacitor . Half went bad . Bought a single capacitor for the load of the half that went bad ( can not remember if it was for the fan or for the compressor ? ) . Ran fine .

A year or two latter , the other half went bad . Bought a second , single capacitor to replace the old one . So , it now has two , single capacitors .

Went ahead and bought a spare motor , seems like stuff goes bad on the weekend , when I can not buy parts . :-(

So far , I have not needed the spare motor . :-)

God bless
Wyr
 
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Old 06-20-15, 12:29 PM
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Thanks everybody for your help. I think its fixed now.

I ended up changing both the motor and the capacitors.

I changed the capacitor first, got two capacitors because I could not find the original dual one in the same type of package, and the original was mounted on a precise oval hole with the capacitor body outside the electrical wire enclosure, sticking out into the condenser area.

It worked for a while, but after a few starts and stops, it was not starting again. So I got the motor too, one of those multipurpose motors that have dual armature for high and low RPM and installed it. The motor was a little bigger and I had to drill a couple of holes on the cover to get it to fit but I'm happy to report that it works now.

The unit makes a smoother sound too.

Now encouraged by this fix, perhaps I can tackle our second AC unit which had a leak and we have not used in a long time. But I'll start a different post for that.
 
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