noise under the engine

there's a rattling noise coming from the under the engine of my suzuki swift. one mechanic told me that it's coming from my a/c compressor. when you start the car and when its idling it makes that rattling noise and when you turn on the a/c or when the engine is already hot, the noise is gone. please help.

find second opinioun from other mechanic.

Well its simple, the mechanic that did the repair for you last time missed some nuts and bolts to put back and now you are having the problem.

i totally agree with samiparker, its probably cos the bolts are loose. it used to happen with me as well. as i reved the car up the noise went away and it came back when i left the accelerator.