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-   -   I want to test a whirlpool capacitor 270-324mfd with a multimeter (https://www.askmehelpdesk.com/showthread.php?t=343394)

  • Apr 19, 2009, 10:22 AM
    jose lora
    I want to test a whirlpool capacitor 270-324mfd with a multimeter
    How much ohms it will read if it is good, or what can of reading I should get if not good
  • Apr 19, 2009, 10:41 AM
    Perito

    A capacitor doesn't really have any "resistance". It does have an "impedance" but not a resistance. With a direct current applied to it, after the capacitor has fully charged, you'll see a near-infinite resistance. You might see an apparent low resistance at first, but the apparent resistance will quickly rise to at or near infinity. Appliance capacitors do have some leakage, so you might see a finite, but high resistance.

    If the capacitor shows a low resistance, it's shot. However, most capacitors fail "open". They basically lose their capacitance. If you don't have a meter that reads capacitance, you probably won't be able to tell the difference between a good capacitor and a bad one -- at least not with an ordinary multimeter.
  • Apr 19, 2009, 01:32 PM
    hkstroud

    To test a capacitor.

    Set multimeter to OHMS or continuity.
    Touch meter leads to capacitor terminals. This charges the capacitor.

    Reverse leads and touch leads to capacitor terminals again. This discharges capacitor.

    If you get a momentary current flow the capacitor is good. If not, the capacitor is shorted.
  • Apr 19, 2009, 02:49 PM
    KISS

    The "good" that hk mentions, I'd change to likely good. You really need to measure ESR or effective series resistance. A cap checker measuring capacitance USUALLY indicates out of tolerance values, but not always.

    "bad' is easy. Good is a little harder to tell.

    I've even had ~0 ohms for a fuse out of circuit, only for the fuse to fail in circuit.

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