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Old 07-31-2011, 12:35 PM   #1
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Capacitor size differences


I had to put a 30/5 mfd on a condesner that had a 35/5. I'm going back in a few days to put the right cap in and to finish the duct work but I was wondering how much of a difference does slowing down that compressor 5 mfd's ( which equates to how many rpm's?) is it?

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Old 07-31-2011, 12:39 PM   #2
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Capacitor size differences


Would it be better to go up 5 or down 5 to get someone by for a few days? For next time.

Thanks.

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Old 07-31-2011, 12:52 PM   #3
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Capacitor size differences


The ideal phase shift is 90 degrees.Run Capacitor will make the motor running like 2 phase. Motor will loose toque.
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Old 07-31-2011, 02:17 PM   #4
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Capacitor size differences


I know that but would faster or slower be better for a few days. I guess neither is advantages
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Old 07-31-2011, 02:29 PM   #5
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Capacitor size differences


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I guess neither is advantages
That would be the correct answer.
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Old 07-31-2011, 05:28 PM   #6
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Capacitor size differences


If I'm not mistaken a run capacitors function is to supply a higher starting voltage to assist in getting the motor to start.
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Old 07-31-2011, 06:16 PM   #7
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Capacitor size differences


http://en.wikipedia.org/wiki/Motor_capacitor
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Old 07-31-2011, 06:28 PM   #8
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Capacitor size differences


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If I'm not mistaken a run capacitors function is to supply a higher starting voltage to assist in getting the motor to start.
That would be a start capacitor.
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Old 07-31-2011, 07:17 PM   #9
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Capacitor size differences


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That would be a start capacitor.
I stand corrected. You are absolutely correct. Sorry Guys. Where is that Crow??
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Old 07-31-2011, 07:55 PM   #10
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Capacitor size differences


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Would it be better to go up 5 or down 5 to get someone by for a few days? For next time.

Thanks.
Either way you are putting an abnormal stress on the motor windings which lead to deterioration.You will be well advised to go back the next day with the right cap.This also gives you the chance to check and make sure that the last guy put the right one in there.
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Old 07-31-2011, 08:15 PM   #11
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Capacitor size differences


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Either way you are putting an abnormal stress on the motor windings which lead to deterioration.You will be well advised to go back the next day with the right cap.This also gives you the chance to check and make sure that the last guy put the right one in there.
Which brings up a very good point, without calling the model and serial number of a condenser or a compressor in to the manufacturer's supply house, how would one determine the correct size cap for a unit?
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Old 07-31-2011, 10:22 PM   #12
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Capacitor size differences


Well a lot of time the UF value will be on the motor or wiring diagram.
The other thing is that most of the wholesale houses will not sell to the home owner for liability and warranty reasons but most will give you the info on a cap.A lot of times the manufacturer will give info like that if the homeowner says they question if the repair was made correctly.
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Old 07-31-2011, 10:39 PM   #13
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Capacitor size differences


Copeland has a book that tells you the cap they recommend. But, the OEM will sometimes use a different one, depending on the coil configurations they are using.
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Old 07-31-2011, 11:28 PM   #14
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Capacitor size differences


I understand both the Copeland Scroll book (which I've never seen) and the stated info on a motor concerning it's respective cap (which I see daily) but if all the data was sun dried off of the unit, the compressor and the condenser fan motor as well as the capacitor and you had no idea what make the unit was, what then?

New unit?
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Old 08-01-2011, 05:00 AM   #15
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Capacitor size differences


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I understand both the Copeland Scroll book (which I've never seen) and the stated info on a motor concerning it's respective cap (which I see daily) but if all the data was sun dried off of the unit, the compressor and the condenser fan motor as well as the capacitor and you had no idea what make the unit was, what then?

New unit?
I don't run into too many 1940s units, so I'm not sure what I would do.

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