Chosen Solution
I just replaced the battery in the machine, verified all the connects a couple of times. One fan spins at full speed 100% of the time and I can’t figure out why. I tried all the standard resets too…any ideas?
Likely the tach within the fan unit has encountered an issue. This could be the fan unit or the wiring to the logic board. Basically, the resistive load of the circuit is not correct. I would start off replacing the fan unit as well as inspect the fan connection point on the upper case (under the logic board) and then following the connection to the logic board connection.
@gadietrich Try getting a new fan and checking the fan connector.
