How to Check a Run Capacitor

By Charles Poole

Start, or run, capacitors are used in motors to help the motor get started. Start capacitors are found in HVAC units, refrigerators and other appliances. If your appliance will not start, you might have a dead start capacitor. You can test these capacitors with a voltage meter to help figure out whether or not you need to replace the start capacitor. This procedure is safe, but you need to take precautions when dealing with any electrical device.

Things You'll Need

  • Safety glasses
  • Gloves
  • Screwdriver
  • Voltmeter

Step 1

Disconnect the power going to capacitor. Put on safety glasses and gloves.

Step 2

Discharge the capacitor by place a screwdriver on top of both terminals on the top of the capacitor. Hold the screwdriver by the insulated handle so you don't shock yourself.

Step 3

Disconnect the capacitor from the appliance by using a screwdriver and pliers.

Step 4

Place the positive (red) lead of the voltmeter onto the negative terminal of the capacitor. Do the same with the negative lead. Look for the needle of the voltmeter to go all the way to the right. If the meter is digital, it should say "out of range" or something similar.

Step 5

Replace the capacitor if you do not yield these results.

Tips & Warnings

  • If the capacitor is bloated or oozing, you need to replace it.
  • Always wear safety glasses and gloves when dealing with electrical appliances.