Priest of the Order of the Butterfly
Posts: 878 from 2003/3/4
From: #AmigaZeux, Gu...
There isn't a lot you can do if you're not willing to open it unfortunately, except maybe keep the room you're running it in cold.
The problem is almost certainly, as geit said, dust buildup under the fan, not the fan itself. You probably won't need to disassemble it beyond opening the case. Get a spudger from Amazon.
https://www.amazon.co.uk/iFixit-opening-battery-changes-smartphone/dp/B00NCFIVH4/Get an air duster, immobilise the fan so its blades can't move, and just blow that old shit out of there. If you don't see much improvement you'll have to take the cooler off and replace the thermal paste, but try without that before.