Thankyou for the SIMPLE but very useful heads up
I seem to have now identified the board causing issue , not sure if i will have ability to repair however
the unit is now running 3 hours without a " FULL ON FAN " issue
( and yes i installed braiins as i need ability to reduce power ( on dark rainy days ) , but increase power on really sunny bright
days as im running these units off of solar
Since the miner is running on solar power what I think is there is a possibility that your power source is not stable or low this can lead to many issues like overheating or like your current issue related to temp error.
I suggest better monitor the power source if the voltage sometimes drops below 220v you can read more here "
Read Temp Sensor Failed"