Help with fans

[mjhall29]

Sorry if this is a stupid question,
I have set the board up and it will print.
It has taken the place of a Radds unit with repetier server running on a pi.
I think i have looked at all the threads on the site but cant see why i cant use a fan.
As soon s i try to use a fan i get problems with the hotend. even when the fan is not on the printer just running next to the bed the hot end seems to start to cool and i get an error. i then have to wait until the hot end has cooled below 45 deg C and restart the printer?
What have i missed?
Regards
Martin

[iDevelo]

You need to tune the heater https://duet3d.com/wiki/Tuning_the_heater_temperature_control

[iDevelo]

And tune it with the layer fan on (at least 50%)

[mjhall29]

Thanks I will do the tune ASP thanks for the quick response.

[mjhall29]

Thanks, Worked first time.