I’ve noticed a strange sounds coming from under the hood recently. I’m thinking it has something to do with my A/C. Reason being that is the only time I notice the noise. The noise isn’t constant but it you can hear it about twice a minute on average and it last about 2 seconds. It’s a low metal on metal kind of sound. It kind of sounds like a distant train brakes (anybody know what I’m talking about?). Any ideas what is maybe? I have a 2004 Colorado Ext Cab 3.5L.