Diagnosing fan problem

[Jesse Sheidlower]

I have a ThinkPad T41p that has had a variety of fan problems
for some time. After my most recent repair things seemed to be
working fine, but the other day I was compiling some ports and
the machine just shut down in the middle; after some
experimentation it seemed clear that it was just overheating
under load and shutting itself off. (Looking at the
temperature sysctl showed that it was getting increasingly hot
until it crashed.)

How can I monitor what is happening? Are there any ways I can
find out from FreeBSD if the fan is even on, or how it thinks
it is working? "systcl -a | grep fan" didn't return anything.
Can I control the fan?

I don't want to make yet another warranty call if they're
gonna say, "It's working fine, it's your OS" or something.

Thanks.

Jesse Sheidlower