I have a similar problem with my 96 Olds 88 - the AC is noisy but still blows cold. I didn’t notice it when I bought the car because I bought it in the dead of winter. I took it to a shop back in April to have it checked out and the guy said it was a noisy compressor and it’* not worth fixing now. He said it may last two months or two years, but just keep using until it goes. So far, so good…

I get the same hum, sounds like it'* coming from deep inside the dash, BUT my AC is OFF when I hear it. I try to ignore it.

Do you get the same hum if the heat is on and AC isn't?