Is there a way from the OS to control the fan speed? There is no LPARs on AIX, we run the OS on bare metal - no virtualization of any kind.
None that i would know of. As far as i know the fans are controlled by thermo-sensors which kick them up when the system gets (too) hot and slower them once the temperature lowers.
Originally Posted by c3rb3rus
I also tried the "diag" command in AIX and didn't find any issues.
You might try connecting to the service processor port and look at the ASMI. In case the system is not connected to a HMC: you need a web browser on the system you connect with and a crossover network cable to connect your system to it (i use a small netbook with Linux for such purposes). You have to configure an IP address out of the address range the interface is configured with (defaults are 169.254.2.147, 169.254.3.147, 169.254.2.146 and 169.254.3.146, see the IBM documentation.
You will find something in the logs there, even when the orange LED has been cleared - if there was anything, to begin with. To me it sounds like one of these thermo-sensors might be broken/somehow dysfunctional, in this case only the hardware support can help. (You *do* have a hardware support contract, don't you?)