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Old 08-29-2011, 06:24 PM   #16
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a hard start kit is a start capacitor and relay.......... again, in order to test a start capacitor you must remove the bleed resistor... if it were good then you would need to resolder the resistor back on. Better off to just replace the start capacitor.... You do understand that a start capacitor is not a run capacitor?

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Old 08-29-2011, 09:37 PM   #17
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Ok. But can you explain the technical aspect of why that would be? I was taught that you check the microfarads coming off the capacitor and as long as it meets the requirements then its good. Am I missing something?
Normal check would be to read the uFs. However, no mete reads uFs under load. Check the voltage.

Full check/test. Check amp draw on start winding. Multiply by 2650, then divide that by the voltage(voltage across the cap). that will give you the uF of that cap.
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Old 08-30-2011, 12:48 AM   #18
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Normal check would be to read the uFs. However, no mete reads uFs under load. Check the voltage.

Full check/test. Check amp draw on start winding. Multiply by 2650, then divide that by the voltage(voltage across the cap). that will give you the uF of that cap.
Whoa you're taking me back to school here where does the 2650 come from? Also why do you need to test the uFs under load? In school they made us pull all the wires off and test it like that... of course we had to neutralize the bleed resistor by tapping a piece of metal across the terminals...
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Old 08-30-2011, 03:00 AM   #19
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Actual microfarads = [ amp (start winding) X 2650 (constant) ] / Voltage

Finding capacitance from measured volts and amps
When testing motor starting capacitors to check the rating when markings aren't readable, the formula often stated is that capacitance in microfarads equals 2650 times the measured amperes divided by the applied volts. Where does this 2650 figure come from?
When an a-c voltage is applied across a capacitor, the resulting current equals that voltage divided by the reactance of the capacitor. That reactance is:
1/[(2)(pi)(frequency)(capacitance C in farads)]
or, for 60 Hertz, 1/(377C). Converting farads to microfarads, then solving for capacitance:
C =[(1,000,000)(amperes)]/[(377)(volts)]
and the value of 1,000,000 divided by 377 is 2650.
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Old 08-30-2011, 06:57 PM   #20
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Many things can test good under a no load condition. but when it has to perform under a load, it fails, or becomes weak.
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Old 08-31-2011, 01:23 AM   #21
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So how do I test the relay to make sure it needs to be replaced? Cause that one is like $50 where as the cap is only $5. I don't wanna waste money...
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Old 08-31-2011, 01:32 AM   #22
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Normal checking of a regular capacitor would mean removing ALL wires from the cap so it is standing alone and not connected to anything and then and only then checking between herm and common for it's rating and fan and common for it's rating, being a dual run cap if so. Plus or minus the given percentage of either rating would be considered within range.
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Old 08-31-2011, 01:38 AM   #23
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In other words if you have a 45/5 dual run cap with a percentage range of 6% than being that the bigger number of any dual cap relates to the compressor and the (much) smaller number relates to the fan motor, 45 multiplied by 6 percent will give you a number. Add or subtract that number from 45 and within those numbers would be considered acceptable. The same on the fan side, the 5. 5 x's 6% will give you the number to add or subract from the original 5 mfd. That's your range, plus or minus.
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Old 08-31-2011, 01:44 AM   #24
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45 multiplied by 6 percent is 2.7.

45 plus 2.7 is 47.7.

45 minus 2.7 is 42.5.

45 plus or minus 6% acceptable range would be 42.5 to 47.7.

I think that's right.
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Old 08-31-2011, 04:46 AM   #25
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So how do I test the relay to make sure it needs to be replaced? Cause that one is like $50 where as the cap is only $5. I don't wanna waste money...
Ohm the contacts and coil. Then check if its opening under load before it should. Or staying closed.
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Old 08-31-2011, 03:20 PM   #26
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and the value of 1,000,000 divided by 377 is 2650.
The formula looks correct. But you need to change the constant to 2652
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Old 09-08-2011, 05:09 PM   #27
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Ok this is where we are at... I replaced the relay and the start cap like beenthere said. There is one problem, there is no run cap... the compressor schematic shows a run cap (I can post a pic when I get to my computer) I called traulson and they told me that they lost all their recrds of all of the units that were manufactured in california when the company moved to new york... how do I determine what run cap to put on this sucker???
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Old 09-08-2011, 05:26 PM   #28
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post a picture of what you are working on as well..... What is the start leg of the compressor currently wired to? other than the start capacitor.....
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Old 09-08-2011, 05:45 PM   #29
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The compressor manufacturer can tell you what size run cap to use.
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Old 09-08-2011, 05:56 PM   #30
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It's usually on the sticker o the actual compressor, not nessisarly the unit

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