strange problem no pin change status

[khriss75]

[khriss75]

Strange, very strange.
Room: kitchen
Devices: #1 Light #Fan

I can switch ON and OFF without any problem the light.
I can switch only ON the fan with no problem.
Impossible turn OFF the fan.
The only way to turn off the fan, is turn off the light
I turn off the fan but the fan doesn't stop.
If I turn off the light, light and fan stops.
Strange strange strange!!!
Fan and light are assigned to 2 different pins...

[khriss75]

OUTPUT don't react

I don't know the way to solve my problem.
Event:

ventola --> fan
calorifero --> heater
temperatura --> temperature
bagno --> bathroom
"CLIMA ventola_calorifero...." is an Arduino output device.

When condition are ok, Homeseer change the status of "CLIMA ventola_cal....." DEVICE to OFF, I can see on log the change (from ON to OFF), all seems to be ok,but there is no arduino pin out change.
Connected to arduino there is an relay (by an ULN2803) to switch on/off the fan.
I changed the arduino pin out but the problem not solved.
If I command the fan ON or OFF manually all works well, no problem.
The event that start the fan works with no problem.
Sometime the "off fan event" works fine, but after some time, arduino output pin don't react.
If I change the status of an other arduino output pin (no connected with fan), the fan stop (arduino fan output state change).
What can I tray?
I'd like to move all my automation from HS2 to HS3 and arduino plugin but this problem stop me...
Please, help me