How about the suspension for the compressor...?
Are all four springs present and possibly adjusted correctly...?
Some people will tighten these prior to a transport and then forget to loosen them again...
Thanks Jim - I checked the mounts last night along with making sure that no line clamps were loose or lines rattling against other parts. It sounds unfortunately like it is an internal noise. It is hard to describle but it is like a rattle/whine noise.
In my garage it is not a problem but my BIL is interested in buying it for his home theater and wants it to be nice and quiet in there.
Regards,
Chad