AC dims lights

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tomtheelder2020

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Our old AC lasted nearly 30 years. When it kicked on, lights throughout the house gave a slight flicker. Our new AC also causes just a flicker but it is clearly more pronounced. Is this a problem?
 

kok328

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Could be signs the A/C compressor is about to fail.
I'd install a "hard start" kit on it and see if that corrects the issue.
Keep in mind this would be a temp fix until you can afford to replace it.
 

tomtheelder2020

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Could be signs the A/C compressor is about to fail.
It seems unlikely the issue is the compressor as the old unit did this for decades and the new one has done it since we first used AC about 4-5 months ago. Is there another likely possibility?
 

Eddie_T

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If the lights are LED they will flicker more than incandescents. Mine flicker when the well pump cycles.
 

tomtheelder2020

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If the lights are LED they will flicker more than incandescents. Mine flicker when the well pump cycles.
That could well be why I perceive the flickering now as worse than in the past. We have way more LEDs now than in the past.
 

BuzzLOL

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The flickering is just the utility transformer outside momentarily lagging as adjusting output up to match the new power consumption load as the high current consumption A/C kicks in...
 

tomtheelder2020

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The flickering is just the utility transformer outside momentarily lagging as adjusting output up to match the new power consumption load as the high current consumption A/C kicks in...
Very reassuring to know. Thanks.
 

bud16415

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My thoughts are different and dimming IMO is a voltage drop problem not likely related to something outside the home if the dimming occurs when something with a high inrush current kicks on. Your service should be sized to handle such loads without a drop.



Undersized wires overloaded circuit or most likely poor connection is what I would look at.



I would start with the panel and make sure all connections both power and neutral are tightened down. I know not why but have seen over time it doesn’t hurt to snug them down.



The fact it happened the same with the old and new AC would rule out a problem with the AC. Is the AC a 240v whole house central air system or just a window unit. Do all lights in the whole house dim or just ones on the same line as the AC.

We have a large window unit that cools the whole first floor and I ran a new line from the panel to the outlet for the AC with nothing else on it. You may need to do that if it is a window unit.
 

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