Please help with Sony Vaio VGN-FS285H heat problem!

Have you tried just using a can of compressed air? You can get them for like 10 bucks at a local office supply or electronics store. Usually very effective and it'll save you some hassle.

It is actually quite easy to disassemble this unit - firstly remove the harddrive and ram covers. Remove the harddrive itself. There is 2 screws under the harddrive cover which screws into the case which needs to be removed. Then remove the 2 screws attached under the RAM cover. Finally, remove all the remaining screws at the bottom of the laptop. Take the BOTTOM cover off and there you go, you can just remove the screws of the actual heatsink - maybe you can apply more thermal paste - might solve the problem too

could be a number of things. most likely if you have had the laptop for a fair amount of time and it has seen regular use the thermal paste may dried and ceased to work properly. also a fan could be dying ( ie bearings or motor going so it doesn't spin as fast as it used to cool things down). Only other thing I could think of maybe there's something blocking your intake or exhaust vents so heat isn't escaping and is just being recirculated.