If your condenser makes a humming noise rather than kicking on the fan or compressor, the problem might be with one of the capacitors. There are probably two capacitors in your AC condenser. These are called dual capacitors and one is the run capacitor and the other is the start-up capacitor. Here's a look at how they work, how they can be damaged, signs a capacitor might be bad, and how an air conditioning repair professional fixes the problem.

Why Your AC Has Capacitors

Capacitors work a lot like batteries. They store electrical energy and provide an additional boost to the fan and compressor when those parts of your AC kick on and run. Your AC may not be able to turn on at all without the help of a capacitor that supplies supplemental power. Since they are electrically charged and connected to the wiring in your condenser, it's best to call a professional to do repair work on the capacitors.

What Causes A Capacitor To Malfunction

A capacitor malfunction is a common reason for air conditioning repairs. One of these electrical parts could last for many years, but if your condenser is hit by lightning, develops an electrical short, or has to run for days during extremely hot weather, a capacitor could go bad.

What Signs To Look For

When a capacitor goes bad, the parts in the condenser may not start up or they may shut down immediately after starting. If the compressor and fan in the condenser aren't working properly, the AC won't be able to cool your home. You'll be wasting money on running your equipment when it can't work effectively. You might hear humming coming from the condenser or smell a burning odor.

How A Repair Technician Helps

The first thing the technician may do is use a multimeter to test the capacitors. The technician has to disconnect power to the AC and then remove one of the panels to get to the wiring and electronic parts inside. The capacitors look like two cylinders on the inside of the condenser. They're held in place with a brace and screws that are removed to free the capacitors after disconnecting the wiring.

The air conditioning repair professional uses a multimeter to tell which capacitor is bad. However, it is sometimes possible to tell if one of the units is bad if it has a bulge or is leaking fluid. Once it's confirmed a capacitor is bad, a new one is put in its place and secured with the brace, and connected to the fan and compressor wiring.

Because a failing capacitor has the potential to cause damage to other parts in the condenser, the air conditioning repair professional might also check the fan and compressor motors to make sure they haven't sustained any damage. If so, the motors may need to be repaired or replaced too.