When my air conditioner cycles on, I notice my lights blink. Is this normal?

A brief flicker when your AC starts up is usually normal

Your air conditioner's compressor draws a short surge of extra power the instant it starts, called inrush current — that momentary demand can cause a quick, minor dip in voltage elsewhere in the house, which shows up as your lights briefly dimming or flickering. A single, subtle flicker lasting a second or less is common and not a cause for concern.

When it's still normal

• The flicker is brief and mild — barely noticeable
• It only happens right when the AC cycles on, not randomly
• Your lights return to normal brightness immediately

When it's worth a closer look

Frequent, severe flickering, lights that dim noticeably and stay dim, or flickering that happens even when the AC isn't cycling can point to a real electrical issue — a loose connection, an overloaded circuit, or a failing component in the AC's electrical system. This is different from the harmless startup dip and shouldn't be ignored.

What could be causing more than a mild flicker

• A failing or weak start capacitor making the compressor draw more power than it should
• Loose wiring at the electrical panel or the AC's disconnect box
• A circuit that's undersized or shared with too much else in the home
• An aging compressor motor that's losing efficiency and pulling harder at startup than it used to

A simple way to tell the difference

Time it: a normal startup flicker lasts a fraction of a second and happens only at the moment the compressor kicks on. If you notice dimming that lingers, happens on multiple circuits at once, or shows up even when the AC isn't cycling, that points away from a simple startup surge and toward a wiring or panel issue worth having looked at.

If the flickering is more than a quick blip, don't wait for it to get worse — call LJ Refrigeration Co. at (480) 948-5004 and we'll check both the system and the electrical connection to it.