How to Check or Test a Capacitor

A capacitor is an electronic device that can store energy in the electric field between a pair of conductors (called "plates"). The process of storing energy in the capacitor is known as "charging", and involves electric charges of equal magnitude, but opposite polarity, building up on each plate

Method #1
You can use your multimeter as an ohmmeter to test the capacitor.

Discharge the capacitor by shortening its leads. That is - use a wire and connect the leads of the capacitor together. This will discharge it.

Put your multimeter in the high ranges 10K-1M

CONNECT MULTIMETER TO CAPACITOR LEADS(OBSERVE THE POLARITY IF ELECTROLYTIC). AT SOON AS THE LEADS MAKE CONTACT, THE METER WILL SWING NEAR ZERO. IT WILL THEN MOVE SLOWLY TOWARD INFINITY. FINALLY THE METER WOULD COME TO BE INFINITE OHMS BECAUSE THE CAPACITOR IS BEING CHARGED BY THE BATTERY OF THE MULTIMETER.

IF THE CAPACITOR IS BAD, IT WILL GO TO ZERO OHMS AND REMAIN THERE. THIS IS CALLED A SHORTENED CAPACITOR

IN THE CASE OF AN OPEN CAPACITOR THERE WILL BE NO OHMMETER INDICATION.

SOME CAPACITORS HAVE A LOW DIELECTRIC LEAKAGE. YOU WILL KNOW THIS IF THE OHMMETER COMES TO REST AT A POINT LOWER THAN INFINITE. TEST A KNOWN GOOD CAPACITOR OF THE SAME TYPE TO BE SURE .

Method #2

Remove the suspected faulty capacitor from the unit. If it's a high powered capacitor, it will still hold a high charge. Discharge the capacitor by using a metal screwdriver with a handle that's insulated. Touch the metal end of the screwdriver to both metal terminals at the same time to discharge any power left in them.

Turn on the capacitor tester and make sure it's getting power. Plug in the tester probes according to the instructions on the meter. Set the selector to an OHM scale before testing the capacitor. Some meters will have an OHM setting pre-set for you.

Touch the leads together so that the meter will zero out by adjusting the wheel on the meter.

Note where the meter points to before touching the wires to the capacitor. Then touch the terminals of the capacitor with the red probe, which will go on the left, and the black probe which will go on the right.

Watch the pointer on the meter. The needle should move away from the left side, or the infinity, and veer toward the right before returning to the infinity. It should move further to the right when the probes are reversed. This means the capacitor is good. If the needle goes all the way to the right side and doesn't return to the left, or infinity side, the capacitor is bad, or it has shorted out