I have an Acer Aspire One 110 Ab that I have upgraded with 1 GB RAM (for a total of 1.5 GB) as well as upgrading the BIOS to version 3309.
Before upgrading the BIOS, which was done in an attempt to improve the stability of 802.11 networking, the acerfand program worked wonders to keep the fan running as little as possible.
Once I upgraded the BIOS to 3309 the acerfand program no longer worked. Instead of turning the fan off the fan was running at full speed for a second every other second.
On March 14th, version 0.07 of acerfand was released and I tried it out in the hope that it would fix the fan issue for by BIOS version. While it did turn off the fan, it caused the computer to reboot after a few minutes. Clearly, this was even worse than the alternative.
I did some trial and error and changed the value 0x20 to 0x21 (two places) for the 3309 specific values. In other words, roughly half-way down in the file, my acerfand file now looks like this:
"${BIOS_VERSION_3309}") #change: handle 3309 seperate 0xAF -> 0x20 R_FAN=55 R_TEMP=58 FAN_CMD_OFF=21 FAN_CMD_AUTO=00 RAW_FAN_STATE_OFF="0x21" ;;
This has completely solved the issue. The fan now stays off as long as the temperature is below 70 degrees Celsius. The rest of the time (which is virtually always) it is dead silent. Case closed. For now.