AC Capacitor: So Small, Yet So Critical


A capacitor is an electrical device that stores electrical charge. The AC capacitor stores electrical power that the AC needs to start up. This is necessary because the AC motor requires a lot of power during start-up, and providing power via the capacitor is the most effective and cost-efficient way to do it.

Causes of Capacitor Malfunction

The capacitor, just like other parts of the AC, is subject to malfunctions. Here are some of the common causes of capacitor malfunctions.


The AC capacitor is made of delicate materials that can withstand a specific range of temperatures. If the range is exceeded, the materials breakdown and the capacitor loses its capacity to store charges. At that point, the capacitor will not be able to provide the necessary power to start the AC.


There is a limit of electrical charges that electrical capacitors can store, and this is the same limit of power that they can discharge (produce). The charge-storing ability of a capacitor is known as its capacitance. You overload a capacitor when you try to draw too much power than its capacitance can provide. This can happen, for example, if you use a lower-rated capacitor than the AC requires. Such overloading can easily lead to capacitor damage.


Lastly, a capacitor loses some of its capacitance every time you charge and discharge it. Over time, the wear and tear of the charge and discharge cycles accumulate, and the capacitor becomes unable to provide the capacitance your AC requires to start.

Signs of a Bad Capacitor

Seeing as to how critical the capacitor is to your AC's operations, you should know if your capacitor starts to act up. Below are some of the telltale signs of capacitor malfunction you need to watch out for. 

Starting Difficulties

Since the main function of the capacitor is to start the AC motor, difficulties during start-up are the classic signs of capacitor malfunction. The AC might fail to start at all or start with some difficulties if the capacitor has malfunctioned.

High Energy Bills

The capacitor stores electricity that it discharges to give the AC whenever the AC starts up. If the capacitor has malfunctioned, the AC will have to draw power from the mains during start-up. This will translate into higher-than-usual power consumption and charges.

Humming Sound From the AC

The AC will struggle to start if it can't get power from the capacitor during start-up. You may hear the struggles in terms of humming sounds whenever the AC starts up.

Contact residential HVAC services if you notice any of these problems.


26 October 2019

Streamline Your HVAC System

As a DIY enthusiast, I started doing everything I could to make my household appliances more effective then ever before. I insulated my attic, worked on cleaning the vents around my kitchen appliances, and eventually turned my attention to my air conditioner and furnace. Unfortunately, the process of taking care of my HVAC system was more intense than I had originally anticipated. I realized that I needed to read about air conditioners and furnaces before I started tinkering around. I made this blog to showcase all kinds of different articles that talk about HVAC, so that you can become a more informed homeowner.