Jetson agx orin developer kit - fan strange behaviour

hi everyone,
i’m having a problem with the cooling system of the jetson orin agx, the fan do just one spin or two and then stops, this cicle continues both in “manual” mode (PWM is set to 255 according to Jetson Power GUI) and in automatic “cooling” profile setting.
under load the jetson reach 70°, i’ve also dismount the fan but didn’t notice any damaged cable.
With jtop if i reduce the speed to zero the fan doesn’t spin but if i set PWM > 0 the usual behaviour occurs.
Please i need help, thank you in advance!

Are you saying that even setting PWM to 255 won’t make it really start to spin?

Yes, exactly. At the moment, the PWM is set to maximum. The fan spins just a couple of times and then stops. Randomly, after some time (usually hours), it starts spinning at full speed and keeps running until the system is rebooted or shut down. This behavior doesn’t seem to be related to the temperature.