How do I fix this? AC popped, makes flapping/whirring sound, still blows cold.

What is your question?

This past weekend, I was on a trip and I turned on the AC unit after I started the car and heard a pop! Now the AC makes a flapping and whirring sound which only gets louder when you turn up the speed of the AC. It still blows cool air but the noise is loud. My dealership charges $85 just to do a diagnostics of it, but no idea what the costs of repair would be. Someone help?