ICX 7150 -> fanless or no fanless ?

Hello,i installed an ICX 7150 48P, and soon as he booted, there is a “panic fan noise, and never stopped.sh ver -> 08.07.70bT211i only have the choice to use the “chassis fanless mode” commande line to stopped the noise.it’s weird ! and the device is quite warm, below the warning limit of course, but warm.and if fan are unable, the noise is too uncomfortable for users.is there a fix ? is this an firmware issue ?any idea will help,thanks,