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  1. #1
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    Frown Can't read start capacitor on hardstart kit

    My meter is very accurate but it won't read the capacitance on start capacitors in hardstart kits. Sometimes it does. Usually it does not. I am thinking it is because of the resistor between the terminals on the start capacitor. My meter has auto ranging. Instead of uF it reads mF and it is wrong anyway in uF even after the conversion from mF to uF. It just will not read it. Otherwise, it is a very good meter. What could be wrong?

  2. #2
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    Are the wires disconnected from the capacitor?


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  4. #3
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    You are reading the resistance of the resistor.
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  6. #4
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    Quote Originally Posted by comfortdoc View Post
    You are reading the resistance of the resistor.


    If the resistor is mounted across the terminals, you are reading capacitive reactance and resistance converted to capacitance.

    Remove the resistor, and it should read normal.
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  8. #5
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    Thread Starter
    Yes, that is what I thought. But on those start capacitors on those kits, the resistor is not removable unless you cut the wire. But then you have destroyed the kit. Also, David Jones on You Tube says that you just read them like other capacitors. Nevermind the resistor.

  9. #6
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    Quote Originally Posted by hvactrekkie View Post
    Yes, that is what I thought. But on those start capacitors on those kits, the resistor is not removable unless you cut the wire. But then you have destroyed the kit. Also, David Jones on You Tube says that you just read them like other capacitors. Nevermind the resistor.
    We all know youtube is infallible.
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  11. #7
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    Quote Originally Posted by hvactrekkie View Post
    But on those start capacitors on those kits, the resistor is not removable unless you cut the wire. But then you have destroyed the kit.
    You can buy 2 Watt, 15,000 Ohm resistors that have 1/4” female terminals on each end for about $2 each.

    That way if you are questioning the start capacitor’s capacitance, you can cut the old resistor off, test the capacitor and reinstall a new bleed resistor by slipping it on the extra terminals on the capacitor.

    A solder Iron will work too, but more time consuming.

    I'm sure it happens, but I haven't seen any weak start capacitors, that weren't already blown apart because the potential relay failed.
    Instead of learning the tricks of the trade, learn the trade.

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  13. #8
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    I’ve found about 6 weak start caps this spring. I was taught to always replace the relay with the cap. If it’s still running when you find it, you’ll have the time to get the oem relay and cap. As others have said, remove the resistor or you’ll get weird readings on your meter

  14. #9
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    I was discussing this with another tech recently, and the only way to get an accurate reading is to remove the resistor. I did an experiment on a cap the was rated 135-162uF. Fluke is the only meter I know of that will read close even if the resistor is still attached (I use a 902 and 87V). Anyway with the resistor attached I read 158uF and with is unattached I read 135uF. It made me wonder if the manufacturer put the tolerance as 135-168uF just to accommodate reading it with and without a resistor.

    Since the fluke is pretty accurate with the resistor attached it makes me wonder if seeing a reasonable capacitance is good enough to verify that the cap is good. There's a lot of debate on the purpose of the bleed resistor and whether or not it should be removed. If you look online you'll see equally credible people saying completely different things about the purpose of it and whether or not you can remove it. At this point the only opinion I think I'll trust is the opinion of the electrical engineer that actually designed the circuit.
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  15. #10
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    My understanding was that the resistor was there to bleed off the charge once it was done starting the motor. That the charge could mess up your heart beating if it discharged into you. I’ve never been sure if that was true or not so I still religiously scratch a screw driver across the terminals as I dont plan on finding out the hard way. I should probably look that up one day. Seen guys cut the resistor off and not replace it with no discernible impact on the motor. Guy that taught me always replaced it for the next guy

  16. #11
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    Cant say ive ever had a problem reading them with the resistor in place... hmm niver even occurred to me


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  17. #12
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    Quote Originally Posted by Makeitcold View Post
    My understanding was that the resistor was there to bleed off the charge once it was done starting the motor. That the charge could mess up your heart beating if it discharged into you. I’ve never been sure if that was true or not so I still religiously scratch a screw driver across the terminals as I dont plan on finding out the hard way. I should probably look that up one day. Seen guys cut the resistor off and not replace it with no discernible impact on the motor. Guy that taught me always replaced it for the next guy
    It prevents excessive arcing across the relay points.

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