After some time it may happen that dirt, and some other crumbs pass through the grid cover of a fan on your Acer notebook.  This will reflect in two ways. Your lap top can increase the heating power or some strange sound may be heard from it.

If you are lucky, just clean or absorb the dust with vacuum cleaner. If the cooling engine is regular, it will work normally again. But, if your Acer notebook makes noise again after that, you will need to check the fan section with appropriate cooling parts.

If you would like to order a used fan, just be careful whether the fun is tested and if you have a warranty.