Lights Flicker When AC Turns On? 7 Possible Causes & Fixes
Have you noticed your lights flicker when AC turns on? While it might seem like a minor annoyance, it could signal underlying electrical or HVAC issues. Understanding the cause and addressing it promptly can prevent potential damage to your electrical system or cooling unit.
This post will walk you through possible reasons why your lights flicker and offer actionable solutions. Here’s what we’ll cover today:
- Why do lights flicker when your AC turns on?
- The 7 possible causes explained (with fixes)
- Pro tips to resolve or prevent flickering issues
💡 Why Do Lights Flicker When AC Turns On?
Your air conditioner is one of the most power-demanding appliances in your home. When it starts up, it creates a sudden electrical draw that can affect other parts of your electrical system. This rapid demand for electricity causes a temporary voltage drop, which may make your lights dim or flicker momentarily.
While occasional flickering is usually harmless, frequent or severe flickering could signal underlying problems, such as faulty wiring or issues with your HVAC system. Addressing these problems promptly can help prevent further complications.
What You Can Do About It:
- Upgrade Your Electrical Panel: If your home has an older electrical system, upgrading the panel can help handle the high power demand from modern appliances.
- Install a Dedicated Circuit: Having your AC on its own circuit can isolate its electrical draw and reduce flickering in other parts of your home.
- Consider an HVAC Maintenance Check: Make sure your air conditioner is functioning efficiently and not pulling unnecessary power due to a fault or wear and tear.
- Use LED Bulbs: LEDs are less sensitive to voltage fluctuations and are less likely to flicker compared to traditional incandescent or CFL bulbs.
- Consult an Electrician: When in doubt, a professional can inspect your wiring, assess your system, and recommend solutions tailored to your home.
🛠️ 7 Possible Causes (with Fixes)
Here are the main reasons behind flickering lights and the corresponding solutions to address them effectively.
1. Voltage Drops from High Energy Demand
When your air conditioning unit starts, it requires a significant surge of electricity to power the compressor. This sudden demand can cause a brief voltage drop throughout your home’s electrical system, often noticeable as flickering lights. These voltage drops are common, especially in older homes or in systems that are already operating near their maximum capacity. While the flickering may seem harmless, repeated voltage drops can strain your electrical system and, over time, reduce its efficiency or even damage sensitive appliances.
Fix
To address voltage drops caused by high energy demand, you can install a soft starter device for your air conditioning unit. A soft starter gradually increases the electrical load during the AC’s startup phase, reducing the initial surge and its impact on your electrical system. Minimizing these surges can prevent voltage drops and protect your electrical system from unnecessary wear. Additionally, consider inspecting your home’s electrical panel. If it is outdated or nearing its capacity limits, upgrading to a newer panel can significantly boost your system’s ability to handle power surges and ensure consistent performance for all your appliances.
2. Circuit Overload
If your air conditioning unit is running on the same electrical circuit as your lights or other large appliances, it may overload the circuit. This happens because AC units demand a high amount of energy, especially during startup, which can interfere with the power supply to other devices sharing the circuit. The result is often flickering lights, tripped breakers, or uneven performance of connected appliances. Circuit overloads can also create long-term issues for your electrical system, including increased wear on wiring and potential fire hazards.
Fix
To resolve circuit overloads, it is crucial to hire a licensed electrician to install a dedicated circuit solely for your HVAC system. By isolating the AC unit on its own electrical circuit, you ensure that it operates independently, without competing for power with other appliances or lighting. This dedicated setup not only prevents flickering lights but also enhances the overall safety and performance of your home’s electrical system. Additionally, it ensures your HVAC unit runs more efficiently without interruptions caused by shared circuits.
3. Loose Wiring Connections
Loose or damaged electrical connections within your home’s wiring system can cause inconsistent power flow. This results in fluctuations that manifest as flickering lights or intermittent power to certain devices. Loose connections may develop over time due to wear, improper installation, or physical damage. Left unaddressed, these issues can lead to overheating, electrical shorts, or even fire risks, making it essential to identify and fix them promptly.
Fix
The best way to address loose wiring connections is to schedule a thorough inspection with a licensed electrician. The electrician will examine your home’s wiring, outlets, and panel to locate any loose or damaged connections. Once identified, they will repair or replace the affected components, ensuring a steady and reliable power flow throughout your home. Fixing loose wiring not only eliminates flickering lights but also improves the overall safety and longevity of your electrical system.
4. Insufficient Electrical Service Capacity
Older homes or homes with outdated electrical systems often lack the capacity to handle the demands of modern appliances, such as central air conditioners. These systems were designed for lower energy requirements and may struggle to keep up with high-demand devices, resulting in flickering lights, tripped breakers, or underperforming appliances. This lack of capacity can also increase the risk of overheating and other electrical hazards.
Fix
Upgrading your home’s electrical service panel is a necessary step if your current system cannot support modern energy demands. A 200-amp service panel, for example, provides sufficient capacity to handle central air conditioners, along with other high-demand appliances like refrigerators, electric ovens, and EV chargers. This upgrade ensures your home’s electrical system can accommodate modern energy needs, preventing disruptions like flickering lights and enhancing overall safety and reliability.
5. AC Capacitor Issues
The capacitor in your air conditioning unit plays a critical role in regulating the electrical supply to the system. It provides the initial jolt of power needed to start the compressor and keeps the system running smoothly. If the capacitor is failing or faulty, it may not deliver the necessary power surge during startup. This can result in inconsistent power flow, causing your lights to flicker whenever the AC turns on. A failing capacitor can also lead to reduced efficiency and strain on your AC’s components.
Fix
To resolve issues with your AC’s capacitor, contact a licensed HVAC technician to inspect your unit. The technician will test the capacitor to determine if it is functioning correctly. If it is failing, they will replace it with a new one, restoring the unit’s ability to regulate its electrical supply effectively. A properly functioning capacitor ensures smooth AC operation, prevents light flickering, and can even extend the lifespan of your air conditioning system.
6. Compressor Motor Problems
The compressor motor is the heart of your air conditioning unit, responsible for circulating refrigerant and maintaining cool temperatures. However, if the motor is old, failing, or inefficient, it may draw excessive power during startup, causing voltage drops and flickering lights. A struggling compressor motor can also lead to higher energy bills, reduced cooling performance, and increased wear on other components in the system.
Fix
If you suspect an issue with your compressor motor, consult an HVAC professional for a detailed inspection. They will assess the motor for excessive power draw, wear and tear, or other signs of failure. Depending on the diagnosis, they may repair or replace the motor to restore efficient operation. Replacing a failing motor not only prevents power disruptions but also ensures your AC performs at its best, keeping your home comfortable and energy-efficient.
7. Utility Grid Issues
Sometimes, the root cause of flickering lights lies outside your home, in the utility company’s power grid. Fluctuations in the power supply, such as those caused by high demand, equipment failures, or maintenance work, can result in inconsistent electricity delivery to your home. These external issues can produce similar symptoms, such as flickering lights, even when your home’s electrical system is functioning properly.
Fix
If you’ve addressed all potential issues within your home and the flickering lights persist, contact your utility provider. Report the problem and inquire about any ongoing disruptions or grid-related issues in your area. The utility company can investigate the issue and take steps to resolve fluctuations originating from their power supply. While you may have limited control over grid issues, staying informed and communicating with your utility provider ensures they can address the problem promptly.
👉 How to Stop Light Flickering Long-Term
If you want to prevent lights from flickering when the AC turns on, here are some additional tips to keep your electrical and HVAC systems in top condition:
Perform Regular AC Maintenance
Routine maintenance is key to keeping your air conditioner running smoothly and efficiently. Tasks like cleaning filters, inspecting coils, and checking refrigerant levels not only extend the life of your unit but also help prevent issues like sudden power surges that can cause flickering lights. A well-maintained AC system reduces energy waste and ensures stable electrical performance in your home.
Invest in a New HVAC Unit
If your HVAC system is outdated, it could be the culprit behind flickering lights. Older units often consume more energy to start up, putting unnecessary strain on your home’s electrical system. Upgrading to an energy-efficient HVAC unit can resolve this issue while lowering energy costs and improving overall performance. A new system is an investment in both comfort and long-term savings.
Sign Up for an HVAC Service Plan
Regular professional inspections can make a big difference in preventing electrical and HVAC-related problems. Enrolling in a service plan ensures that experts check your system periodically, identifying and fixing small issues before they escalate into costly repairs. This proactive approach can save you time, money, and stress in the long run.
Use LED or CFL Lights
Switching to LED or CFL light bulbs is an easy way to reduce the impact of power fluctuations in your home. These energy-efficient bulbs are less sensitive to minor voltage changes compared to traditional incandescent bulbs, meaning they’re less likely to flicker. They also last longer and consume less electricity, making them a cost-effective choice.
Monitor Power Fluctuations
Installing a home voltage monitor is a smart way to stay on top of your electrical system’s performance. These devices track voltage levels and alert you to irregularities, allowing you to address issues before they lead to bigger problems. Monitoring fluctuations can help pinpoint the cause of flickering lights and protect your appliances from potential damage.
⚡ AC-Induced Flicker
When your lights flicker every time the AC kicks on, it’s more than just a minor annoyance—it could signal an underlying issue that needs professional attention. At Comfort Systems of Montana, we’re the team you can trust to keep your home safe and comfortable. With years of experience, certified technicians, and a commitment to your satisfaction, we’re here to diagnose and resolve the problem quickly and effectively.
Don’t let flickering lights disrupt your peace of mind—contact us today to schedule an inspection and ensure your cooling system runs smoothly all summer long!