A friends X-Trail has a blower problem. A/C system blows cold air but very little power from the fan. Could this be the ballast resistor?. If so where can it be found?
The fan speed control unit, referred to in Nissan doc as the Fan Amp Unit, is bolted into the side of the fan blower bodyshell. It uses air from the fan to keep cool.
Your symptoms suggest that the blower motor itself may be at fault as usually when a resistance goes futt it's the slowest speeds that go, you usually get full speed or nothing.
In my case I had to remove the motor, regrease the bearings to restore operation, and replace the resistances in the fan speed control module as the stuck fan had caused a lack of cooling to the module with the inevitable burn out.