HVAC Electrical Buzzing

[Alex Bush]

Hi fellow BPers, I'm having issues with my outside HVAC unit - it's making electrical buzzing noise that's too loud and makes it uncomfortable to be in some of the bedrooms in my house when AC is running.

The noise it's making is this https://1drv.ms/v/s!AneU_VTSiG...  https://1drv.ms/v/s!AneU_VTSiG...

I already had two AC people come in to inspect it and one couldn't even diagnose what was happening (he said "it's just old") and the other one suspects it's a condenser but wasn't sure and thinks it's better to replace the whole unit.

The previous owner of the house says it's only 4 years old and should be fine. 

Did anyone experience something like this? What would you recommend me do, replace the whole unit or keep looking for AC repair people who can finally tell me what's wrong?

Thank you in advance!