Why js there a loud buzzing noise coming from the compressor, the unit is brand new

the power grid may not be up to full power

happens after a power up every electric unit left on in the grid
on a storm all kick in in a massive load

turn off at the wall
unplug
plug back in
see if compressor startup again

Is the buzzing coming from the compressor, or from the switch itself?

Take a look at this YouTube page that explains with good videos what are some of the common problems with heat pump noise. The one that seems dominant is the defrost cycle a heat pump goes thru when it melts ice off the evaporative coils. In defrost cycle, The compressor runs but the cooling fan does not, so you will hear a loud buzzing sound and the unit sounds like it is stalled...because only the compressor is running to generate heat to melt coil ice.

https://www.youtube.com/results?search_query=American+Standard+5000+Heat+Pump+makes+a+buzzing+noise
Defrost cycle noise video:
https://www.youtube.com/watch?v=wudLk0WoIVo

thats a good sign the valves that those coils you replaced sit on are getting bad and you will sooner or later need a brand new gas valve

Have someone check your pressures & temperatures in your refrigeration system. Also check the compressor amps with an analog meter to see if the amps fluctuating. There might be something wrong with the compressor.

if everything is running may just be contactor,if compressor is running not fan turn it off call service tech out(Fan motor bad)if fan is running but no compressor turn it off call service

Since I could get no one to tell me about new freezer compressor making buzzing noise while on, I had the store come a pick it up and give me my money back.

I have a Amana ASD2622HRW Lately there is a loud buzz that comes and goes. We cleaned everything and blew it out under and behind the fridge. And it still is happening. Any suggestions? It still cools fine. But this Buzz is so loud that you can hear it through the house. Please help!

either the noise is coming form he ice maker fill valve( but if its of and still aking noise i doubt it. it also possible that the noise is coming from the compressor itself, overheating nad trying to restart in which case would give a slight "buzz" noise for 5secs or so then "click" off, and wait maybe 3 min to restart again. look for melted ice andperhaps your ice dream ont as hard as it should be???

sounds like just a vibration caused by cols hitting the frame perhaps, sometimes a pull from underneath the unit on the condenser coils will rectify the problem(id give a pretty quick tug, . unit could just be settling into the floor or the house settling around it, vibrations are definitely annoying but usually no need for alarm