Why Are My Lights Flickering When My AC Turns On?

image of kitchen a lights depicting  lights flickering when AC turns on

Flickering or dimming lights when you switch on your air conditioning unit is a prevalent issue that many people encounter. Numerous factors can contribute to this phenomenon. This guide aims to shed light on the most common causes. Electrical issues, wiring problems, and outdated equipment are among the culprits explored in this article. You will find practical tips on addressing and resolving the problem yourself, along with guidance on when to seek professional assistance. Continue reading to dive deeper into the reason your lights flickering when AC turns on.

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Is It Normal for Lights to Flicker or Dim When the AC Turns On?

Flickering or dimming lights when your AC turns on is a fairly common occurrence. This happens because the air conditioner demands a substantial amount of electricity during startup. The sudden surge in power consumption can cause a momentary voltage drop. 

When the AC compressor activates, it requires a greater power boost to initiate the cooling process. This sudden electrical demand can briefly decrease the voltage within your home’s electrical system. It can affect other devices connected to the same circuit, including lights. As the AC stabilizes, the voltage should normalize, and the flickering lights should subside.

However, persistent or severe flickering may indicate a more significant issue, like an overloaded circuit or faulty wiring. In such cases, consult a qualified electrician who can assess the situation and perform any necessary repairs or upgrades.

Take note that the following expectations apply unless you have a geothermal unit:

  1. Brief flickering or dimming of lights
  2. Lights may dim by approximately 3-5% or potentially more.

Standard outdoor air conditioning units draw a higher electrical load compared to geothermal air conditioners. Geothermal units derive their energy from the earth’s depths. Their control unit is typically located near the furnace. If the geothermal unit is straining your electrical system, you will require the expertise of a specialist.

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Indication of A Bigger AC Unit Problem

air conditioner wiring

When the AC turns on, and you notice persistent or severe flickering of lights, it could be an indication of an underlying electrical system problem. Here are some potential causes to consider:

  • Overloaded Circuit: If the circuit handling both the AC and lights is overloaded, it can lead to flickering lights when the AC turns on. This situation poses safety risks and can gradually damage the electrical system. 
  • Faulty Wiring: Faulty wiring is another potential culprit that causes voltage drops and various electrical issues. If the flickering persists, it may indicate faulty wiring that requires repair or replacement.
  • Low Voltage: Insufficient voltage supplied to your home can result in flickering lights when you turn on your AC. This could stem from problems in the power grid or the transformer supplying power to your residence. 
  • Damaged or Weakened AC Capacitor: Similar to a weak or defective car battery, a compromised AC capacitor can lead to a significant drop in electrical power. This can substantially decrease light output. Typically, the lights will dim by approximately 30 to 50 percent. If you observe this issue, seek professional assistance to assess and evaluate the AC capacitor. 
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How to Stop Lights from Flickering/Dimming When You Turn On Your Air Conditioner

To prevent lights from flickering when you switch on your air conditioner, you can take the following measures:

  1. Check the Electrical System: Hire a qualified electrician to inspect your home’s electrical system. They will assess and inspect for overloaded circuits, faulty wiring, or other issues that may cause voltage drops.
  2. Upgrade the Electrical System: If your electrical system is outdated or inadequate for your requirements, upgrading may be necessary to handle the load of your air conditioner and other appliances. This could involve replacing the electrical panel, upgrading wiring, or installing additional circuits. 
  3. Use a Hard Start Kit: Installing a hard start kit can reduce the strain on your compressor during startup. This minimizes the voltage drops and prevents lights from flickering. This is a cost-effective solution that a professional can install. 
  4. Use a Dedicated Circuit: If your air conditioner and lights share the same circuit, consider installing a dedicated circuit specifically for your air conditioner. This guarantees that the AC receives the necessary power without affecting other appliances on the circuit.
  5. Install Voltage Stabilizers: Voltage stabilizers help regulate the voltage in your home, preventing fluctuations that can cause lights to flicker. While this is a more expensive solution, it offers long-term benefits and protects your electrical system from damage. 
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Do Not DIY Air Conditioner Electrical Problems

image of homeowner conducting diy air conditioner electrical repairs

For safety reasons, avoid do-it-yourself (DIY) attempts to address electrical issues related to air conditioning or lights. Dealing with electricity can be highly hazardous. It can lead to severe bodily harm or even fatalities if mishandled. AC and lighting systems operate at high voltages. They present significant risks to individuals without proper electrical training. 

Apart from the physical dangers involved, attempting to fix electrical issues without the appropriate expertise and knowledge can exacerbate problems and lead to costly repairs. Electrical systems are intricate. Even seemingly minor issues may have underlying causes requiring the expertise of a trained professional for accurate diagnosis and repair.

Hire a licensed and highly qualified electrician to handle any electrical concerns. They have the knowledge, training, and equipment to perform the work safely and effectively. Electricians can ensure the safety and functionality of your home or business. 

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Being attentive to flickering lights when the AC turns on is crucial for maintaining safety, comfort, and peace of mind. These flickers can indicate underlying electrical issues that require immediate action from qualified technicians or electricians. Neglecting these signs can lead to severe electrical problems. Take a proactive and vigilant approach in promptly identifying and addressing these issues. Being proactive helps keep your home safe and comfortable. It will give you the peace of mind that comes with knowing your electrical system is functioning properly.

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