I've recently been noticing a rattling come from under my hood. The other day I looked underneath, only to hear a annoying rattling coming from what appears to be the compressor area next to the engine block. Leaving the engine running, I thought to turn fan on low (1) without the a/c on. As soon as that kicked on, the rattling stopped. Any thoughts other than leaving my fan on all the time

, to get that annoying rattling to stop?