Air Conditioning 101: What Does an AC Capacitor Do?

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One of the most essential parts of an air conditioner is the capacitor. Without it, your air conditioner won't start up and function properly. These battery-like units work to power up the air conditioner, and provide a jolt of electrical signals to keep the motors and fans in an air conditioning system running.

In this article, we'll see how AC capacitors work, and their importance in an air conditioning system. We'll include ways for you to diagnose a failing AC capacitor, as well as the cost of a new capacitor as a replacement.

What Is An Aircon Capacitor?

The AC capacitor is an electronic component inside an AC unit designed to store charge in an electrostatic field. This means it functions as a temporary storage device for electricity, where the AC unit can be used to stabilize voltage and start the motors in its cooling system.

The capacitor looks like a large battery, due to its cylindrical appearance, and terminals on each end that connect to an electrical circuit. However, AC capacitors and batteries work differently. Where batteries solely provide power to a device, an AC capacitor is able to store energy to maintain a constant charge on the air conditioner motors.

What Does an AC Capacitor Do?

An AC capacitor basically acts as a temporary battery to keep the HVAC system running with a consistent power supply throughout its cooling cycle. Upon start up, the start capacitor provides the initial power burst to jolt the air conditioning system to power up.

The AC capacitor is necessary to run an AC unit, as the motors inside your air conditioner are powered by the capacitor. Singapore-made air conditioners, for example, usually come with three motors: the fan motor, the compressor, and pumps - and all three of these are powered by the capacitor.‍

The Importance of an AC Capacitor

1. Initial AC Power Surges

The start capacitor provides that initial jolt of energy that the air conditioning system needs to power on its motors. This powerful burst of energy can jolt up to 500% of the normal energy capacity it takes to run the air conditioner, activating the motors to function properly during start up.

2. Ensures Consistent Power Supply

As the air conditioner provides cool air into the room, it needs constant power to run. The capacitor is what regulates the electrical power going into the unit, and ensures the air conditioner is getting constant, and consistent energy without overloading the components. This is essential for the AC system to create cold air without overheating or tripping breakers.

Diagnosing a Faulty Capacitor

#1 Air Conditioner Won't Turn On

The capacitor is what jumpstarts your air conditioner, and if your AC unit is plugged in but won't start, then the problem is potentially with the capacitor. Capacitors run without rest, and are susceptible to wear and tear. This causes AC units to stop working, and refuse to power on as there is not enough energy passing provided by the failed capacitor.

#2 Air Conditioner is Short Cycling

If your air conditioner is turning itself off only to turn back on, then turning itself off again in short intervals, then your AC unit is short-cycling. Some reasons for an AC system to short-cycle include a dirty air filter, a frozen AC unit, and an overheating system, but a failing capacitor also makes the list.

The capacitor may have trouble maintaining a steady and consistent power supply to the unit, which is causing the unit to short-cycle in random, short intervals. Since it is difficult to pinpoint the cause of a short-cycling AC, it is best to have your unit checked by reputable AC repair services like Luce Aircon.

#3 AC Unit is Making a Humming Noise

If your AC unit is making a loud, high-pitched or low humming noise, then there is most likely an issue with a failing capacitor. A humming sound is one of the bad AC capacitor symptoms, and is often indicative of a failing or failed capacitor.

#4 Rising Electrical Energy Bills

Rising energy bills is a tell-tale sign of a bad capacitor. While there may be other causes for the increase in your electricity bill, a capacitor that can no longer regulate the amount of electricity flowing through your HVAC unit will tend to consume more energy than average. This would reflect in your energy bills, which may increase exponentially.

Costs of a Replacement Capacitor

A new capacitor can set you back between $120 to $250, depending on its voltage rating, and model of your air conditioner. The price will also depend on whether your air conditioner uses single capacitors, or dual capacitor components.

AC capacitor replacement is a relatively common air conditioner repair service, and most technicians will be able to diagnose bad AC capacitor symptoms to recommend a full replacement of the air conditioner capacitors.

Broken Aircon Capacitor? We’re Here to Help

A busted air conditioner capacitor could always result in the slow and untimely demise of your aircon unit. But with immediate repair and maintenance, the problem should be solved in an instant. Get the job done conveniently and easily!

If you’re dealing with capacitor issues, give us a call or message us here today at Luce Aircon.

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