What does an Air Conditioning Capacitor Do?

AC Capacitor – A Deep Dive

Your air conditioner is a machine that’s truly the sum of its parts. Even something as seemingly minor as a capacitor can sideline your AC system if it goes out. Below, we’ll go in depth on AC capacitors plus the role they play in your air conditioner and how you can keep capacitor failure from taking your AC system out of commission.

A Small Part with a Big Job

Say the word “capacitor” and, if it doesn’t draw a complete blank, most people will think about the ones found on circuit boards. But an AC capacitor isn’t your ordinary capacitor. For starters, they’re much bigger than their circuit board-bound cousins. Think lantern battery-sized.

So, what is something that big doing in your air conditioner, in the first place? As it turns out, your AC system needs a helping hand when it comes to start-up. The average AC system draws a lot of power – more than your home’s electrical system can supply, in most cases.

Unlike batteries, capacitors excel at delivering short, strong bursts of energy. And that’s exactly what your AC system needs on start-up. A typical AC capacitor delivers that extra boost of energy, only to go dormant once more with a stored charge until it’s needed for the next start-up.

Your average AC system may have multiple capacitors – one for starting the condenser fan motor, another for starting the compressor, etc. Some are even “dual capacitors” – effectively two capacitors in one housing with a commonly shared connection. These are designed to deliver more power while maintaining a more compact size, which helps in mini-split and other small form factor AC systems.

Common Causes of Failure

It’s not uncommon for AC capacitors to fail, especially as your AC system ages. Overheating is a surprisingly common cause of failure, particularly for unshaded and poorly ventilated AC units. Capacitors can also die suddenly from old age, mostly due to deterioration of the components within. Choosing a capacitor with an insufficient voltage rating can also shorten its lifespan significantly.

Fortunately, you can tell when your AC capacitor is close to throwing in the towel. In most cases, you’ll see the following clues given off by a dying capacitor:

  • Inability to start or takes longer than usual to start
  • Random shut-offs
  • Loud humming noises during operation
  • Little to no cold air during operation
  • Burnt or noxious odor from air conditioner
  • Energy bills that increase without explanation

What You Can Do

AC capacitors are inexpensive to replace, but you’re better off having an experienced HVAC technician tackle the job. The capacitors themselves are a high-voltage item and mishandling them could put you at risk of electrocution or worse. Poor installation can also have some shocking consequences for your AC system, not to mention it could potentially void your system’s warranty.

The seasoned experts at Cool It HVAC have the experience and speed to fix your AC capacitor problem before you lose your cool. They also specialize in other types of HVAC repair, so give them a call whenever you’re having AC trouble.