Lights Flickering When the AC Goes On? Here Are 10 Possible Reasons

Have you ever noticed a brief flicker in your home’s lights when you switch on your air conditioning system? While this might seem like a small annoyance, it could be indicative of underlying electrical issues that need addressing.

Taking a proactive approach by understanding these issues makes it easier for you to take the right steps to ensure your home’s electrical system is safe and efficient. Whether it’s a simple fix or a sign of something more serious, it’s always a good idea to reach out to an electrician if you are dealing with these issues.

Here are 10 reasons why your lights may flicker when you turn on the AC.

1. Circuit Overload

One common reason for lights flickering when the AC starts is circuit overload. Air conditioners are high-power appliances that draw a significant amount of electricity. When you turn on your AC, the initial power draw, often referred to as the “start-up load,” can momentarily overload the circuit, causing lights to flicker.

Your home’s electrical system is designed to handle a specific amount of current. When a high-powered appliance like an air conditioner kicks on, it can momentarily exceed the circuit’s capacity. This brief period of overload can cause other devices on the same circuit, such as lights, to dim or flicker temporarily.

2. An Aging Electrical System

If your home has an older electrical system, this could be another reason why your lights are flickering. Older systems may not have the capacity to handle the electrical demand of modern, high-powered appliances like air conditioners.

Over time, electrical wiring can also degrade, reducing its ability to transmit electricity efficiently. Once the air conditioner is turned on, the sudden surge in electrical demand can stress these aging components, leading to flickering lights. Regular inspection and ongoing maintenance of your electrical system can help identify and resolve these issues.

3. Voltage Fluctuations

Voltage fluctuations in your home’s electrical system can also cause your lights to flicker when the AC switches on. A voltage fluctuation, or a sudden change in the power being supplied, can result from several factors, including power supply issues from the utility company or issues within your home’s wiring.

Whenever you turn on your AC, it needs a surge of power to start up. This surge can cause a temporary drop in the voltage, leading to flickering lights. While this is generally harmless, regular occurrences might indicate a more serious issue with your electrical system.

4. Inadequate Electrical Capacity

Inadequate electrical capacity refers to a situation where your home’s electrical system doesn’t have the capacity to support all the appliances you’re using. This can be a particular problem in older homes that were not designed to handle today’s electricity-hungry appliances.

For example, once an appliance with a large electrical load, like an air conditioner, is switched on, it draws a large amount of power. If your home’s electrical capacity is insufficient, this can cause a noticeable drop in voltage, resulting in flickering lights. You might need to upgrade your electrical system if you regularly experience this problem.

5. Faulty Wiring or Connections

Faulty wiring or loose electrical connections are common causes of flickering lights, especially if high-power appliances are running. These faulty connections can create resistance, affecting the steady flow of electricity and leading to flickering lights.

The additional load can exacerbate these issues when an air conditioner is switched on, making the flickering much more noticeable. If you suspect that faulty wiring or connections might be causing your lights to flicker, you need to reach out to a professional electrician to inspect your home’s electrical system.

6. Short Cycling

Short cycling is a situation where your air conditioner repeatedly turns on and off over a short period, as it can also cause your lights to flicker. This constant turning on and off puts a significant strain on your home’s electrical system, which can manifest as flickering lights.

The causes of short cycling can be numerous, from an oversized AC unit to a dirty air filter or low refrigerant levels. If you notice your air conditioner short cycling, it’s advisable to get it checked by a professional HVAC technician to prevent damage to your AC and your home’s electrical system.

7. A Malfunctioning Compressor

The compressor is the heart of your air conditioning unit, responsible for circulating the refrigerant necessary for cooling. A malfunctioning compressor can draw more power than usual when the AC is switched on, which can cause your lights to flicker.

Compressor problems can be caused by various issues, including age, lack of maintenance, or mechanical failures. If you suspect a problem with your AC compressor, a professional inspection is necessary. Ignoring a malfunctioning compressor can lead to more significant AC problems down the line.

8. Electrical Interference

Certain appliances and devices can cause electrical interference when they are switched on. This interference can affect the steady flow of electricity, leading to flickering lights. An air conditioner, with its high power draw, can be one such device.

Electrical interference is typically more of a nuisance than a serious problem. However, if you notice persistent flickering every time you turn on your AC, it could indicate a larger electrical issue that a professional should investigate.

9. Using Energy-Efficient Bulbs

Energy-efficient bulbs can sometimes flicker when paired with high-power appliances. These bulbs use less energy and work differently than traditional incandescent bulbs, making them more susceptible to fluctuations in voltage.

The temporary fluctuation in voltage can cause these types of bulbs to flicker once you turn on a high-energy appliance like an air conditioner. If this is the case, the flickering is usually harmless and doesn’t indicate a larger electrical problem with your system.

10. Issues With the AC Unit Itself

The problem could also lie with the air conditioner itself. If the AC unit is aging, has faulty parts, or needs a major repair, it can draw more power than usual, leading to flickering lights whenever it’s turned on.

Fortunately, regular maintenance of your AC unit can prevent many of these issues. If your AC is causing the lights to flicker, it’s a good idea to have an HVAC professional inspect the unit to make sure it’s working properly.