Did you test to see if it works when powered or has this other fan failed.
Also, tell the forum about your yearly cleaning. Example at http://reviews.cnet.com/4520-11319_7-6240575-1.html
Why does the fan in the heatsink of my PC kick in and run continuously? If I do a warm or cold re-boot on the PC, the fan does not kick in immediately. Today it didn't kick in for an hour, but when it did, it never stopped.
Do I need to replace the heatsink?
The regular fan isn't running at all.