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3 Reasons Lights Flicker When Your Home’s AC is On

As a homeowner you may have noticed your lights flicker when you power up your air conditioning unit. What causes your lights to dim?  Could it be a problem with the AC unit itself? Is there something wrong with the electricity in your home? Our Beaverton residential heating and air conditioning pros answer these questions and more. 

Understanding Your Residential Air Conditioning Unit

Think of electricity in your home the same way you do your residential plumbing. Much like the water in your pipes, there is only so much electricity available in your home at any given time. When you flush your home toilet while running a shower, the water pressure splits between the two fixtures. Electricity behaves in a similar manner. 

AC-normal-light-flickeringWhen you turn on a high-energy device, like a modern AC unit, the initial power draw can put a substantial drain on your available electricity. This can cause your lights to dim. While flickering lights might seem worrisome, this is often a normal electrical response to power being diverted. 

How can you tell if the dimming lights are a normal occurrence or signs of a larger problem? For a normal functioning air conditioner, you will experience: 

  • Lights dimming for a split second
  • Lights losing only about 5% of their brightness 

Lights that dim for a long time, flicker on and off rapidly, or only dim on particular circuits could be symptomatic of more serious electrical issues. What are the more serious issues and when should you speak with a professional?

1. Damaged or Loose Wires

Do your lights turn off and on quickly when you start up your AC unit? This could be indicative of loose or damaged electrical wires. Faulty wires can cause current loss to your lightbulb. Plus, the voltage drop that occurs when your air conditioner kicks on can exacerbate the problem, making your lights flicker rapidly. Not sure if your wires need repair? Make an appointment with your Beaverton HVAC contractor to check if your wires are discolored, charred, or loose.

2. Weak or Broken Capacitor

ac-lights-flicker-capacitorIf your lights are losing 30% to 40% percent of their illumination when the AC starts, that’s a sign of a capacitor issue. Your AC capacitor functions like a battery, giving your compression motor the boost of energy it needs to power up. Much like your car battery, your air conditioning compressor can lose its ability to store and maintain power. 

What does this mean? Your AC is pulling more voltage from other appliances and putting more stress on your compressor to start up. This can cause the lights to temporarily lose their brightness.  

3. Overloaded Circuits

Overloaded circuits can present a serious problem. According to the National Electric Safety Code, all major appliances should be on their own dedicated circuit. If you trip your circuit breaker, or hear any buzzing sounds when you turn on your AC unit, you could be overloading your circuits. If you notice any of these signs, unplug any household devices that share the same circuit as your AC unit. This will reduce your risk of fires and electrical shock. For a long term solution, you will need to get a complete assessment and potential repair from your HVAC professionals. 

Home HVAC Solutions in Beaverton & Portland

If you aren’t sure what might be causing your flickering lights, call in the experts. AAA Heating and Cooling is your go-to residential HVAC servicing and installation company. We now have two locations, in Portland and Beaverton!