Eric,
You need to tell the software which direction you need. Use the following command to set the fan direction in the system CLI:
fan prefer-direction slot 1 port-to-power
Depending on the fan tray, you can also set power-to-port.
I mostly use port-to-power. As I said, it depends on your fan tray model. The direction is set at the factory and cannot be changed.
If this is an IRF setup you'll need to do it for each slot in the IRF.
Don't forget to save the configuration after you issue the command so that it will be set appropriately the next time the switch boots.
Regards,
David