The ambient temperature of miners should always be maintained below 35 degree Celsius .
For example, a S9i hash board working temperature is 85 degree Celsius maximum, anything beyond will cause the miner to go into high temperature protection mode and shut down.
To check, you can access the miner's kernel log. The picture below depicts the high temperature warning which is shown in the miner’s kernel log.
Other miners such as S9, T9 and L3+ will also go into this mode when temperature exceeds what's allowable.
It is essential to get to the root causes of high temperature. Switch off the power for approximately 2 minutes and then reboot the miner. However, if the ambient temperature gets too high, the miner will still stop working and shut down because of the high temperature protection mode.
Lower down the ambient temperature so as that the miner’s temperature won’t get too high.
Dust accumulation in the miner will also lead to high temperature protection, please dismantle the front fan to clean the dirt.
If all the above method did not help and the temperatures are escalating, thus affecting hash rate, please return the miner for repair.