If you're lounging out in the yard and keep hearing an odd humming noise, you should check if it's coming from the AC condenser. Humming could mean the capacitor is dying and you need to have it replaced.

You'll want to take action since the capacitor could die soon, and then your air conditioner might not function; but even worse, the compressor or condenser fan motor may be damaged from trying to start with no power from the capacitor. Here's how the condenser capacitor works, why it goes bad, and what an AC repair technician might do for the problem.

The Capacitor Supplies Extra Power To The Motors

The purpose of the capacitor in the AC condenser is to provide extra power to the fan motor and compressor when they start up. The motors struggle to start unless they get enough power. The capacitor stores power so there is plenty on reserve to get the motors going.

The fact that the capacitor holds power makes doing AC repairs yourself dangerous. A capacitor can give you a serious shock even if the power to the AC is shut off. The capacitor needs to be discharged before trying to replace the part.

Capacitors Can Wear Out Due To Age And Heat

It's fairly common for a condenser capacitor to give out during a heatwave. When it's excessively hot outside, the temperature in the condenser soars even more since the refrigerant releases heat inside. This causes the capacitor to overheat and fail. Old capacitors have a higher risk of failing too, so if your AC is old, it's possible the capacitor might fail during the hottest days of summer.

A Bad Capacitor Needs To Be Replaced

An AC repair technician can test a capacitor with a multimeter to verify it's bad. The only solution for a bad capacitor is to replace it with a new one of the same rating.

The AC repair technician has to remove the condenser panel to access the capacitor. It's usually right on the side of the condenser in an accessible location. The capacitor is held in with a bracket, and it's attached to wiring.

Once the wires are removed, the capacitor is pulled out and a new one is installed and hooked up to the wires. The capacitor is ready to start working immediately. The repair technician restores power to the unit and then starts the AC to make sure the fan motor and compressor start right up and that there are no odd noises coming from the condenser anymore.