Whatever you do: DO NOT PUT A VACUUM ON IT AND MAKE THE FAN TURN REALLY FAST!
It's a lot of fun, but it kills the bearings. Apart from that: The fan may be clean, but there's an entire carpet of dust on your air vents, believe me. You do want to take it apart.
I'd love to help you, but that wouldn't be cheap
@ Matious: Suspect the flatcable that connects screen and motherboard.
This can be an expensive one if it's soldered...