I used Acer Aspire One very often these days. Just feel the fan is too noisy. I think it is time to clean it now.
But, it is not a PC. It is a Netbook. Very compact. How to disassemble it?
I googled it and found a very good guide here.
I follow the steps and disassembled it and took the fan off. Clean the fan and installed it again.
Everything is fine, except the SSD is not found by Bios. I have to redo it to make sure the cable of SSD is perfectly installed.
Now it is very quiet when the system is on.