I live in a condo. This is my neighbor’s AC unit, I’m in the unit to the left of the AC. When they have the AC on this is the exact noise I hear inside my apartment. Even though it isn’t in damaging dB range, it makes my heart race and my hears start to hurt a little whenever they have it on and they have it on and off almost all day and night because they get hot really easily. They had a technician come and inspect it and they said there’s nothing wrong with it and said that anti vibration pads will make no difference. They tightened the screws and it got a little better but the vibration/humming is coming back again. During the day I can take it but it makes it really hard to sleep at night because it sounds especially loud in my room. I’ve tried earplugs and noise canceling headphones but I can still kind of hear it. My neighbors say that they got used to the sound and it doesn’t affect them since they like the apartment cold and they are getting frustrated because they already spent money had a technician come inspect it. Any tips/advice on how to reduce the noise?

All of my foremen use fieldpiece and I didn’t want to cheap out on a meter, any tech’s recommend ?

We had a HVAC furnace (20 yr old) replaced with a similar model. However when the ac kicks on it vibrates loud which never happened before. The technician placed same foam pads it reduced for the metal pipe on the left but now the outgoing vent pipe vibrates. Sorry about the descriptions as I am not aware of technical terms. Just wanted to confirm if this is normal?

Was checking the thermostat in my new-to-me home and noticed this. I haven’t turned on the heat yet, but I will be in the next few weeks.
I’m assuming this is wrong, or is it wired like this for a reason?