Refrigerators keep food cold only when all of their parts are working together properly. If you hear a clicking sound when the compressor runs, or if you suspect the compressor is running too often or too infrequently, the refrigerator's run capacitor could be faulty and in need of replacing.
Many refrigerators have wiring diagrams located on the back of the appliance. This diagram will tell you where the parts are located. The run capacitor is located in a white or black box near the compressor. The wiring in this box tells the refrigerator's compressor when it needs to run to cool the refrigerator's contents. Normally, a compressor should run only a few of times an hour, but it may run more often if the refrigerator is opened and used frequently. The run capacitor is a part of the appliance's start relay. The run capacitor powers up the compressor when the PTC — another piece located inside of the box — gets hot. This heat turns the capacitor on, which makes the compressor run, and it cools down the refrigerator.
An electrical issue usually is what causes the run capacitor to malfunction. When the PTC doesn't correctly indicate the refrigerator's temperature, the run capacitor won't know when to turn on. It could turn on too frequently or not at all. When the capacitor is not working properly, usually you'll hear a clicking sound either before or after the compressor turns on. When you're checking whether the run capacitor is working properly, you can use a power meter to gauge how much energy is being passed between the PTC and the run capacitor. Your owner's manual should tell you the amount of energy that should be passed if it is functioning properly.
Keeping the area near the compressor and the run capacitor clean can help prevent problems. Unscrew your refrigerator's grate, which usually is located below your refrigerator or at the bottom back. Wipe down the compressor and the run capacitor box with a water and mild soap mixture. Regularly vacuum any dust that accumulated near the refrigerator's hardware with your vacuum's brush attachment.
Because refrigerators run on electricity, repairing, cleaning or assessing any part of the refrigerators hardware can be extremely dangerous. Before you begin any inspections or repairs, unplug the refrigerator and turn off the breaker that controls the power in that part of the house. If you're not comfortable around large household appliances, contact a professional instead of risking ruining the refrigerator's hardware or injuring yourself.