06 Z, drivers side kicks in when idling for too long, the drivers side also kicks in if you put the air con on, but i'm yet to see the passenger side radiator fan kick in..is it only supposed to kick in at a certain temperature ? I asked stu on here and his passenger side one didn't spin either just his drivers side. Car isn't over heating, temps never exceed just under half way on needle ( i know they aint super accurate but still).