If the Avalon A1166Pro kernel log shows Fan3 [0] Fan4 [0] (as shown in the figure below), it means that two fans of the Avalon miner are faulty. Again, you can refer to the methods in this article for troubleshooting.
Troubleshooting:
1. The fan cable is loose or damaged; its recommended to reconnect the fan interface or replace the fan data cable with a new one;
2. The fan is damaged, replace the damaged fan directly.
Click the article below to learn more!