The dimmer isn't made for LEDs
Older dimmers were designed for incandescent bulbs that draw much more power. With LEDs they often flicker, buzz or won't dim smoothly. The fix is an LED-compatible dimmer, and many let you adjust the low end so bulbs don't flicker at the bottom of the range.
The bulb isn't dimmable
Check the box or the base of the bulb. A non-dimmable LED on a dimmer circuit will flicker and fail early. Mixing brands on the same dimmer can also cause uneven dimming.
Loose bulb or connection
A bulb that isn't fully seated, or a loose wire in the fixture or switch, can make lights flicker when the fixture moves or the fan runs. This one needs the power off before anyone looks inside.
Lights dim when the AC kicks on
A brief dip when the air conditioner starts is common, because the compressor draws a big surge. If the dip is large, frequent, or affects the whole house, it can point to a loose connection in the panel or at the service. That's worth a check, and whole-house issues may need the utility.
When to stop and call
Call right away if flickering comes with a burning smell, a warm switch or outlet, buzzing from the panel, or lights that brighten and dim across the whole house.
Need a hand with this?
Text a photo of the fan, fixture or panel and you'll get a price by text.