Q&A for How to Check a Start Capacitor

The capacitor may have a bulge on top if it's faulty. Otherwise, when you're checking the capacitor with a multimeter, the readings will be far above or below the listed range on the unit.

Remove the start capacitor from the AC unit and look for a bulge on the top of the capacitor. Otherwise, use a multimeter to check.

You can use a DMM for this purpose. Connect the probes to the terminals of the charged capacitor. If the reading shows a minus sign then you've connected the positive probe to the negative terminal of the capacitor.

A capacitor is created out of two metal plates and an insulating material called a dielectric. The dielectric can be made out of all sorts of insulating materials, including paper, glass, rubber, ceramic, plastic or anything else that will impede the flow of current.

By using a bridge rectifier . You could add a noise-filtering electrolytic capacitor on the bridge output. The voltage that you rectify should should be 3/4 of the maximum capacitor operating rating. Example: 12v AC bridge 12v DC out 16v 1000uF capacitor (for this example, using a capacitor with less than 1000uF may not give you adequate noise filtering).

You can find them in larger hardware stores; the price (depends on quality) ranges from $15 to $30 and up.

The capacitance can be measure with a multimeter with a capacitance range. Since the label is missing, the maximum working voltage (max WV) of the capacitor would be unknown. The capacitor should be replaced with the same or higher max voltage. Find another of the same appliance and see if the capacitor has a label. Or get another one from the manufacturer of your appliance.