1994 Cadillac EL Dorado howling under hood

Started to hear a noise several days ago, not very noticeable at first. Started car up in morning on third day and the noise was extremely loud. It is coming from the passenger side. Checked power steering fluid and its fine, oil level good too. Can't detect where noise is coming from because it's so loud, could be power steering pump, belt tensioner, A/C pump or alternator? At around 1500 rpms the noise starts to diminish but is still there. At higher rpms it almost has a high pitched metalic sound. Put car in gear and turned steering wheel to hear if noise changed, nada! Don't really want to take car for test drive because of potential major engine damage. Car is in show room mint condition inside and out.