Maybe this is nothing, but I would rather ask now than pay more later. I have a 2016 Mustang EcoBoost and I have had it for two years. Until this week the AC was great. Now every time the AC turns on, I hear a short rattle at the front of the engine. It sounds like small stones inside a tin can. It lasts about three seconds and then it stops, and the air still comes out cold. It mostly happens on the first start of the day, or when the car has been parked in the sun. My dad says it is only a loose cover and I should forget about it. My friend has an older Mustang GT and he said a rattle when the AC starts could mean the compressor clutch is getting weak. I did not even know the compressor had a clutch. So one evening I read about it online. I opened a page about Mustang cars on a Sharjah website to learn how the belt, the pulley and the clutch work together. It said a small noise can come from a worn clutch or a weak belt part, and that fixing it early can save the compressor. That made me feel a little better, but also more careful. Then a coworker told me to look for an Expert Mustang AC specialist near Industrial Area 10 and let them listen to the noise while the engine is running. He said a good mechanic can often hear the problem before using any tools. I liked that idea, but I am not sure how to explain the sound. So I have some questions. Is a short rattle only when the AC starts usually the clutch, or can it be the belt too? Is it safe to keep driving for a few weeks, or can I damage the compressor if I wait? Should I make a video of the noise with my phone and show it to the garage? And if only the clutch is bad, can they change just that part, or must I buy a whole new compressor? If you had the same noise on your Mustang or another car, please tell me what it was and about how much you paid. Thanks a lot.