One of the most surprising facts about central air conditioners is that they actually need more power than residential electrical systems provide. When the AC in your Norfolk, VA home starts a cooling cycle, it relies on its capacitor to ramp its motors up. Without a functioning capacitor, an air conditioner may run indefinitely, but it will never have the ability to bring indoor temperatures down. However, even as they rank among the most important components in AC systems, AC capacitors are both overworked and little understood. Following is everything you need to know about AC capacitors, including what you should do when yours stops functioning.
How AC Capacitors Work
An AC capacitor is located in an air conditioner's outside condensing unit. Although an air conditioner is connected to and powered by a home's electrical wiring system, its energy demands exceed the output of this system every time a cooling cycle is started. At the beginning of a cooling cycle, the capacitor sends out several quick jolts of electricity to the air conditioner's motors. These jolts rev the motors up to start the cooling cycle. Once the cooling cycle is engaged, the capacitor ramps its energy output down and provides a steady stream of power to support the cooling cycle through its end. When the ideal temperature has been reached in the interior of your home, your thermostat sends a signal for the AC to turn off. As soon as the cooling cycle ends, the capacitor starts storing up energy for the next round. In essence, as long as your air conditioner is on, your AC capacitor is never at rest. If it isn't actively working, it's actively preparing for the next cooling cycle. As such, it is easily one of the hardest working components in your air conditioner. When you buy a new air conditioner, you'll be given information on the model's expected lifespan. For most ACs, this is about 15 to 20 years. However, even though your air conditioner might be rated to last this long, this doesn't mean that all of its components will. In most households, AC capacitors need to be replaced approximately twice throughout an air conditioner's lifespan.
Many Air Conditioners Have Two Capacitors
A single, dual-function capacitor can both rev up your air conditioner's motors for the cooling cycle and then keep them running until the cooling cycle reaches its end. However, some air conditioners have two separate capacitors for each task. They have a start capacitor that sends out a short series of quick jolts, and they also have a run capacitor that provides a continuous stream of energy. If your air conditioner has two capacitors, you may find that only one capacitor fails and the other continues working. In this instance, an HVAC technician might recommend having both capacitors replaced with a single, dual-function unit. Dual-function capacitors cost more upfront, but they make future capacitor replacements both cheaper and easier.
Common Signs of a Failing AC Capacitor
One of the most common signs of a failing AC capacitor is an overly warm home. Without this component, the cooling cycle won't start and indoor temperatures won't go down. Other signs of capacitor problems include:
- Loud humming sounds coming from the AC condenser
- Having your air conditioning shut off without warning
- Burnt odors or smoke coming from the outdoor condenser
Capacitor problems are common after power outages. Without surge protection, the sudden restoration of power can burn these components out.
7 Reasons Why AC Capacitors Malfunction
Not only is their job an especially taxing one, but capacitors are subject to all of the excess wear and tear that comes from frequent power surges. If you deal with regular short circuits or live in a home where the lights constantly flicker off and on, finding and resolving the underlying electrical problem is important for preserving your AC capacitor. AC capacitors can also be damaged by blunt force due to falling objects such as broken tree limbs, faulty wiring, and direct lightning strikes. One easy way to protect your AC capacitor is by having a surge protector installed. In homes that experience frequent power surges, whole-house surge protection can be essential for protecting costly appliances like the air conditioner, and all other valuable devices that are constantly plugged in.
The Dangers of Attempting to Replace a Failed Capacitor on Your Own
In many ways, AC capacitors both function and look quite a bit like batteries. However, this is where their similarities end. When a battery fails in any device or appliance, it can be swapped out. Unlike batteries, capacitors are directly hardwired into air conditioners. It takes special tools, training, and skills to get them out and correctly reinstall them. More importantly, given the very high risk of electrocution, attempting a job like this one can lead to serious injury and even death. It's also important to note that major projects like capacitor replacement should always be performed by licensed professionals if you want to keep your AC warranty intact. Even simply tampering with your air conditioner's capacitor can void the unit's warranty altogether. Once this happens, all future repair issues will have to be paid for out-of-pocket even if they're the direct result of defective parts or substandard materials. Finally, replacing a failed capacitor with the right capacitor for your air conditioner model isn't as easy and straightforward as it might seem. This is especially true if your AC capacitor has been replaced before. Attempting to buy a replacement capacitor with the exact same specifications as your current one may cause the problem to recur if incorrect capacitor specifications were the cause.
How to Deal With a Damaged AC Capacitor
If your air conditioner won't turn on or if you've got persistent humming sounds coming from your air conditioner's outdoor condenser, you can assume that the most likely cause of the problem is a failed or failing capacitor. However, there is no way to accurately diagnose this issue on your own. There are many other reasons why cooling systems make strange noises, fail to cool down building interiors, or randomly turn themselves off. The only way to know for certain whether the capacitor lies at the heart of the issue is by having a licensed HVAC company perform diagnostic testing. HVAC professionals use cutting-edge tools to measure the voltage, resistance, and current of capacitors, among many other factors. If your AC system is exhibiting any of the symptoms of a failed capacitor, turn it off right away. Attempting to run a cooling system that cannot enter a cooling cycle can result in excess wear, overheating, and other issues. An HVAC technician can verify whether your capacitor has failed and may even be able to tell you why. When there are obvious and correctable sources of excess capacitor strain, HVAC technicians can also share helpful preventative strategies. For more than 40 years, Miller’s Heating and Air Conditioning has been serving residents of the greater Virginia Beach area. We offer reliable heating, cooling, plumbing, and electrical services. If your AC capacitor is no longer working, we can help. We even offer options in whole-house surge protection that can help extend the lifespan of this important component. Call us today to schedule service.