Tuckers Air Conditioning, Heating & Plumbing Blog

Electrical AC Issues: A Closer Look at Capacitors and Contactors

Whenever we talk about why “do-it-yourself” isn’t an option when it comes to air conditioning repair, we mention just how complicated the modern AC is. It’s not only an intricate refrigerant-based system that requires special licensing to handle, it’s also a complex electrical device with motors, wires, a control board, and numerous other electrical intricacies. This is why an HVAC repair technician must have years of training and pass special licensing tests.

Today we’re going to take a look at two important parts of the electrical system inside an AC: the capacitors and the contactors. These are temporary parts that eventually wear down to the point that they’ll need a professional to replace them. If you schedule annual maintenance for your air conditioning system, technicians will catch early on when these parts need to be replaced. But even with this level of care, you may have an air conditioning system that suddenly won’t work because of failed capacitors or contactors.

What Exactly Do These Parts Do?

Capacitors and contactors work together to regulate and manage the flow of voltage to the motors. The simplest explanation is that capacitors send voltage jolts to the motors of the AC, and the capacitor controls whether any voltage is allowed to flow to the motors.

Capacitors are something like temporary batteries. They store electrical charges and then send voltage periodically to the motors powering the compressor and fans. There are two different capacitor types, and each motor has both. The start capacitor does the job of sending the initial voltage charge that starts the motor up. The run capacitor is what keeps the motor running with periodic voltage.

Contactors are like on/off switches for an air conditioner. When a contactor is closed, it permits electricity to flow to the compressor and outdoor fan motors. When open, electrical current stops.

What Can Go Wrong With These Parts?

As when mentioned earlier, both capacitors and contactors are temporary parts that will often need to be replaced before the air conditioner itself needs to be replaced. Technicians always examine these parts during maintenance to look for signs they might be failing (for example, corrosion on a capacitor or a capacitor that’s started to expand) so they can have them replaced before they fail.

Capacitors will eventually start to lose their ability to hold an electrical charge. Extensive heat exposure speeds up this process. When a capacitor starts to die, it will create a clicking sound at start-up. When the capacitor fully dies, the motor won’t start and instead give off a humming noise. Call for repairs when you hear either sound—trying to run a motor with a busted capacitor will cause the motor to burn out.

A contactor can wear down as well, but may also lose its connection if it becomes dirty. If the compressor in the air conditioning system won’t turn on or won’t turn off, it may be a failed or dirty contactor.

You need to have a Frederick air conditioning contractor take care of electrical repairs for your cooling system—there’s a danger of electrical shock if you try to do the work on your own!

Schedule service to repair your AC. At Tuckers Air Conditioning, Heating & Plumbing, we pledge to exceed expectations at every turn.