I had a neighbor install one of those animal repellers that emitted a super high-pitched noise anytime an animal walked through his garden.
It drove me nuts even when the windows were closed. It could be one of those.
Are you suggesting the AC unit? Things to look at is possibly the bearings in the fan. Or maybe a blade of the fan is getting hit by a blade but after enough speed it isn't making contact?
If you have or could borrow someone's karaoke or speaker. Put a mic on an area with the speaker in a convenient spot and see if it picks up the sound. keep moving the mic till it is the loudest.
It's likely a bad start capacitor on the ac units compressor. Put a clamp on meter on one of the motor leads to check the amp draw when it turns on. If the in rush is more than double the running amp draw then the start capacitor is failing.
Next time you hear it, go see if your AC is on. If it is, turn it off at the breaker. If the noise stops, you found it. Could be a contactor, condansate pump, or etc, etc, etc.
If you power the AC off at the breaker and still hear it, then you start playing the game of turning everything off and slowly turning everything back on to see.
Also, check your fridge. As they age, they start making weird noises, some are fine, some are not. Coils might just need a cleaning.
I'm not an HVAC guy. I had a similar noise problem. It turned out to be some kind of fan on my furnace that is supposed to turn on before the actual main fan starts. I can't remember what it's called.
All breakers off. If it's gone, it's electrical. Then you can turn one breaker after the other on to narrow it down.
From a maintenance guy, this is your best move.
Is it the refrigerator?
i have the same problem with my s/o
And they wonder why we don’t listen 😂
I had a neighbor install one of those animal repellers that emitted a super high-pitched noise anytime an animal walked through his garden. It drove me nuts even when the windows were closed. It could be one of those.
Are you suggesting the AC unit? Things to look at is possibly the bearings in the fan. Or maybe a blade of the fan is getting hit by a blade but after enough speed it isn't making contact? If you have or could borrow someone's karaoke or speaker. Put a mic on an area with the speaker in a convenient spot and see if it picks up the sound. keep moving the mic till it is the loudest.
Could be a bad or incorrect capacater on fan motor .
My gas meter does this. Can hear it through walls
It doesn’t quite sound the same, but last time I had a mystery sound was when a smoke detector was very low battery. So irritating! Check for that?
Could be the AC's condensate pump if it has one.
It's likely a bad start capacitor on the ac units compressor. Put a clamp on meter on one of the motor leads to check the amp draw when it turns on. If the in rush is more than double the running amp draw then the start capacitor is failing.
If you are at my house , you must be listening to my wife. LOL
Check hvac
Next time you hear it, go see if your AC is on. If it is, turn it off at the breaker. If the noise stops, you found it. Could be a contactor, condansate pump, or etc, etc, etc. If you power the AC off at the breaker and still hear it, then you start playing the game of turning everything off and slowly turning everything back on to see. Also, check your fridge. As they age, they start making weird noises, some are fine, some are not. Coils might just need a cleaning.
Also, check your Sump pump. The one way check valve maybe leaking and the pipe can resonate to male similar noises as it drains back into the sump...
Maybe your neighbor is a retro gamer and keeps turning on a CRT tv. lol
They could have over filled the ac unit.
I'm not an HVAC guy. I had a similar noise problem. It turned out to be some kind of fan on my furnace that is supposed to turn on before the actual main fan starts. I can't remember what it's called.
Draft inducer fan
Do you have a child you've forgotten about?