iBook whirs whenever power cord plugged in?

So this started happening out of nowhere. There's a buzzing/whirring noise that comes out of my laptop whenever I put in the power cord. At first I though it was a battery or cord issue. I replaced both, and it still makes that sound. Furthermore, it only gives me a charged symbol for the battery life, and won't charge the battery. Help? I really can't afford a new laptop right now, so any assistance is appreciated.