Pappy they are so tough to deal with. The fact you have to pay for them just to come out for a diagnostic makes me angry
They know their fridges have a problem with the compressors. The first tech at my house told me so. He was so confident that was the problem that he did not even do a "diagnostic". He told me that they replace them all the time.
Could just be as simple as the condensor fan that was failing causing the griding noise or something(water line) is caught on the fan blades.
They use a really small condensor and fan. It also uses a special refrigerant that costs 3X more than the standard stuff. The compressor is lightweight and cheap. I am surprised they give a 10 year warranty on it. But then again it probably cost them very little and they still charge you to replace the compressor if it fails and that is total BS!
Don't expect it to be fixed today but you make sure that he puts some gauges on the thing to make sure the refrigerant pressures are good also. I wish I had with the first guy :'(