How to put an electric fan on a Chevy Blazer?

I have a 2001 chevy blazer. I can't get the original fan off. I've taken all 4 bolts off but it didn't come off. There is one massive bolt in the center which goes back to the block, but i wasn't sure if that was the right one. So what do I do now?|||you sure you took off the right bolts.... and then give it a wacksomethings they are four bolts in the fan and four bolts in the fan clucth either ones it should have come off if you had bump it a bit|||Try turning the big bolt in the opposite direction that you were trying. Sometimes these have left handed threads because otherwise the fan would come loose as the engine turned it.