Why does the light in the same room as my window air conditioner unit dim ON when the air conditioner unit is on? this happens when the light switch is on the OFF position and only happens on one outlet in the room... the light is an led and dims very little. also the light is not on a dimmer.

  • I wonder if the high load of the A/C is pulling enough current to induce a voltage in the light's wiring? LED lights can operate on very little voltage, but not sure if this is possible, but the wire for the A/c would have to run near the wire for the light for some distance.
    – JPhi1618
    Jun 28, 2019 at 19:54
  • Do you have a VOM (aka multi-meter)? Are the a/c receptacle and the light on the same breaker? Jun 28, 2019 at 19:54
  • 1
    By "dims very little", do you mean that the light is just a bit dimmer than full brightness, or did you intend to say "the light is very dim, barely lit"? Jun 28, 2019 at 23:31
  • I believe he is using the word "dim" incorrectly. As i read it: the light is off and when the AC kicks on the light-bulb also comes on but just a little, meaning the light is on but "dim", not at full power. I.E. the light is dim, it does not dim down. Correct me if i am wrong. "this happens when the light switch is on the OFF position and only happens on one outlet in the room" I do not know what it means that - it only happens on one outlet. Perhaps it means it only happens when the AC is plugged into one particular outlet. ?
    – Alaska Man
    Jul 2, 2019 at 18:30

1 Answer 1


Call a trained electrician and get them to take a look at it.

Electricity is dangerous, and it sounds like you've got mains voltage leaking between at least two circuits - and it's entirely possible that things like the wall or floor of that room are currently electrified, depending on how the leakage is occurring. Trying to fix it without formal training could potentially get you killed or your house burned down - and is potentially illegal, depending on where you are located. I can say with a certainty that it's definitely legal in Australia, at the very least.

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