Recently I have replaced both fans on SRX220 to a slightly more powerful ones (and more quiet) and now I would like to lower the fan speed when there is no need for such efficency.
Putting aside any safety and support aspects:
Is it possible to change the fan speed under 'normal' temperature threshold on SRX220? Any hidden CLI commands, anything?
I do not think there is any direct way to increase/reduce the fan speed but you can try to set temperature thresholds accordingly.