Loud unidntifiable Buzz

[Terryk]

I have a Tempstar N4A3 2.0 Ton 13 SEER Single Stage Central Air Conditioner, about 5 years old. About 4 times this season and last year, it would start an extremely loud electronic sounding buzz.  I recorded the sound on my phone. I couldn't pinpoint the source when I stood at the unit. It stopped when I turned off the AC. The tech from the HVAC company we bought it from thought it might be the blower but wasn't sure. He checked the amps. He said he'd talk to the more senior guys at work and play the sound for them. That was 4 days ago and I haven't heard back.
Any ideas?

[Admin]

Post the video here.

[Terryk]

I couldn't upload my own recording, but found this one below on Youtube, it's the exact same buzz. So it seems to be the contactor but we hear it right at the ductwork at the AC unit in the basement. Unfortunately we didn't go outside to the condenser when the noise occurred.

https://www.youtube.com/watch?v=FilZHf5EpPE&t=13s

[Admin]

You could turn the breakers off to the outdoor unit and if you still hear the buzzing then it's likely the 24V contactor coil.

I'm surprised the technician came to look at this problem and didn't go to the outdoor unit or take that control panel cover off.

First I would identify if the noise is coming from the outdoor unit or the indoor unit.

If you registered the air conditioner you should have a 10 year warranty on parts.

[Terryk]

Thanks for the quick reply. I'll check the warranty.