What AC Capacitors Do and How to Know When They’re Failing

AC capacitors are nothing short of genius. These components store up energy in anticipation of forthcoming cooling cycles. When AC compressors need a boost at startup, the energy reserves of AC capacitors get their motors going. Without a working AC capacitor, your air conditioner would never have enough power to actually cool your Tampa, FL home. Read on to learn more about how these components work, why they’re so important, and how to know when they’re nearing the end of their lifespans.

An In-Depth Look at How AC Capacitors Work and Why They’re Necessary

When cooling cycles start, an air conditioner’s short-term energy demands greatly exceed the standard power supply. Even though your AC unit is wired directly into your house’s electrical system, this high-powered equipment requires a quick and incredibly intense burst of energy to get moving. This pre-cycle rise in energy demand can often be seen in older homes that lack updated electrical systems. When air conditioners kick into action and enter cooling mode, lights flicker and all other active appliances take a brief pause.

AC capacitors look and function a lot like batteries. These units harness and store electricity all throughout normal AC operation. This prepares them for each successive cooling cycle so that they’re always ready to provide the necessary boost of power for restarting the compressor motor. However, despite their similar looks and functions, AC capacitors and batteries aren’t the same. While dead batteries can be safely removed from most appliances and replaced or recharged, bad AC capacitors should only be handled by licensed professionals. These units hold between 5 and 80 microfarads of electricity at all times. Even when your AC unit is turned off and completely disconnected from your power supply, its AC capacitor poses a serious risk of burns and electrocution if mishandled.

How to Know When an AC Capacitor Has Failed

One of the most obvious signs of a failed or failing AC capacitor is the inability to initiate a cooling cycle. Without a working capacitor, your air conditioner might start and make its normal range of sounds, but it won’t move any cool air into your living space. Lacking the power to start its compressor motor, an air conditioner can’t pump refrigerant to and from the indoor air handler. Heat transfer won’t occur, so indoor temperatures will remain unchanged.

If your AC capacitor is nearing the end of its lifespan but still functioning, you may notice your air conditioner taking far longer to enter its cooling cycle. Louder than normal humming sounds during AC operation, clicking noises burnt odors from the outdoor condenser unit, and random cooling system shutdowns are other common signs of capacitor issues.

Different AC Capacitor Types

Most air conditioners have dual or dual-function capacitors in their outside condenser units. Older AC models and some basic AC designs have two separate capacitors instead: run capacitors and start capacitors. The start capacitor delivers a massive burst of energy at the beginning of each cooling cycle. The run capacitor stores and releases sufficient energy throughout the cooling cycle to keep the compressor motor running.

Dual capacitors handle both jobs. Having an air conditioner with a dual capacitor can minimize your repair costs in the event of capacitor failure. When your AC capacitor fails, you’ll only have one unit to replace. Comparatively, if you have a cooling system with separate run and start capacitors, you’ll have to replace both components at once. This remains true even when only one capacitor fails. Given that both capacitors are subjected to the same environmental conditions and sustain similar wear and tear, replacing them together with an AC repair service is the best way to avoid additional problems in the near future.

How Long Do AC Capacitors Last and What Causes Them to Fail?

A top cause of AC capacitor failure is normal aging. In ideal conditions, these components can last two full decades. With most modern air conditioners lasting between 15 and 20 years, you might never experience AC capacitor problems at all. However, certain conditions can expedite capacitor wear and lead to problems within just five to 10 years of AC installation. For instance, AC capacitors don’t hold up well in extremely high temperatures. If your AC condenser is installed in an unshaded location that gets lots of direct sunlight, you can probably expect this component to die out at least once or twice during your AC unit’s lifetime.

Certain events can also damage AC capacitors irreparably. For instance, if your outside condenser/compressor unit is hit by a lightning strike during a summer storm, you’ll definitely need to replace this component. Even mini power surges that occur throughout the year can shorten the lifespan of an AC capacitor. If you’ve had to replace your air conditioner’s capacitor more than once before and constantly deal with flickering lights and appliances in your home, you should consider having whole-house surge protection installed.

Incorrect installation and incorrect capacitor specifications can also lead to problems. AC capacitors have very specific voltage ratings. As such, attempting to replace an older unit with a new, low-voltage option could result in diminished performance and rapid failure.

What Happens When You Run an Air Conditioner With a Bad Capacitor?

Running an air conditioner with a bad capacitor will leave you with a hot, humid house. With no refrigerant being circulated, you can’t expect your indoor temperature to go down. One of the most common signs of a failing capacitor is a sharp rise in home cooling costs. If your energy bill is far higher than normal, it’s probably because your AC unit is running longer and struggling to get its job done. Unfortunately, continuing to run your cooling system after its capacitor has gone out can also lead to motor failure and the premature breakdown of other important components. Thus, if you suspect that your capacitor is under-performing or isn’t working at all, turn off your air conditioner and schedule service right away.

Can You Replace a Bad AC Capacitor on Your Own?

The major challenge in replacing an AC capacitor as a do-it-yourself project is the serious risk of electrocution. Lacking the right training and experience, there isn’t any sure way to prevent electrocution entirely. However, there are cost considerations that should be accounted for as well. Installing this component incorrectly could damage your AC compressor or your compressor motor. This could leave you with out-of-pocket repair costs that are far higher than the cost of professional capacitor replacement. Moreover, tampering with your AC capacitor or any other component that’s connected to your AC motor will automatically void your manufacturer’s warranty. It can also void all other AC protections that are supplied by your home warranty and home insurance plan. The only safe and truly cost-effective way to replace this essential component is by hiring a licensed HVAC company to do it for you.

At Air 24/7 Air Conditioning & Heating, we serve residents of Tampa and the surrounding communities. We offer superior heating, cooling, and indoor air quality services. We also provide solar panel installation, maintenance, and repair services. If your air conditioner is malfunctioning or it needs a new capacitor, we can help. Call Air 24/7 Air Conditioning & Heating today to schedule an appointment.