I use the FT-897 with the optional Antenna-Tuner FC-30.
It always makes me nervous if a fan is running, but in modern rigs it seems to be a normal (annoying) thing. Nevertheless this waste valuable energie when you use the FT-897 as a portable with its internal NiMh-Accus.
If the FC-30 is connected its fan runs all the time - thats needlessly ! So I decided to integrate a temperature-switch ...
I found a small circuit at www.conrad.de with the order no. 114421, sized like a stamp. You only have to cut the fan wireing and integrate this circuit - very easy.
Adjust the circuit that it switched off the fan at a normal (room-)temperature. A LED is on the module ... its very helpful and there is no need to connect the fan for adjustment.
Then place the temperature-sensor near the coil in the FC-30; - I fixed the circuit with double-side tape.
Thats all !