If the switch works fine and only gets hot. I would check if the fan is spinning or damanged. Sometimes I cant tell the fan is spinning because it is so quite. In this case I take a little paperstrip and push it through the radiator until I hear a noise from the fan hitting the paperstrip.
To check if the fan is damanged I would open the switch and look the can spin freely. Alternatively you can messure the current the fan is drawing.