Is it my compressor? on 2005 Ford Escape

When you turn the vehicle on it start to make this knocking/rattling noise. It was only happening every now and then and when parked. But in the last few day it has gotten to where as soon as you turn the truck on it starts. Someone told me it was the compressor, but I'm not sure.

2 answers 2 comments
Could be...could be any of the other pulleys.
ok thank you
seek est and diag it could be idler or tensioner
it started making it when the AC was turned on, now it happens even with the AC off.