How to turn on hot end fan to check if it can still be running?

[mnidannydang 2]

Hello, i want to turn on hot end fan for ultimaker 2 but don't know how to do it because i uninstall the heater block and buy a new one, so now i can't heat up the nozzle and thus the hot end fan can't be turnt on automatically by heating up the nozzle. Is there any way i can turn this hot end fan on by gcode or something? If so how do i run the gcode in ultimaker 2. Thank you.

[Smithy 1,146]

As far as I know, there is no gcode for it, the hot end fan is turned on by the firmware when the nozzle is about 40°C (or 45°C). When this is not working for you, you have some other problem or your new heater is not working as expected. Check also the PT100 which measures the temperature.