Laptop is hot and noisy

[Aguiluz]

My laptop is an Acer Aspire 3050. 1 and 2-6 months old. When I got it new, the fan barely turned on, even under some load. Now it's on all the time, very noisy. Can't sleep with it on. No applications loading it past 7% CPU.

I tried vaccumeing vacuuming the intake port, and vacuuming the exhaust many times. It behaved like it was brand new, but after a day it was noisy again. Any suggestions? I'm out of ideas!

I also noticed that 75% of the intake was covered in stupid plastic by the manufacturer. Should I try to take it off?

EDIT: I found a pic in Google Images. The Green box part is covered in plastic, and the blue part is open. The red is just from some other guy. Didn't make that.