When I Open AC, Engine Make A Sound... What Is ??? Do U Know ???

[saabturk]

Hi my SAAB Friends...
I have got SAAB 9-5 SE Automatic 1998 years. When i start the engine, it is working regulerly. But when i start engine and air condition, my engine is making HRRRR HRRR And when i push a gas a little, sound is normally. What you think about that ??? Sorry my english friends.

[jlrSAAB]

I have the same sound in My 1997 Opel Omega, an old car and I think old compressor belt require to be replaced for a new one.