I just replaced a mechanical timer switch (noisy) with a digital switch. The old switch had red, white, and black wires and the new switch has red, white, blue wires. I simply connected the new blue wire as if it were a black wire. Now I have a bathroom fan (in a different room than the switch) that responds to the timer. This fan was not controlled by the old switch, so I wonder if the old switch was faulty (we’ve only owned the house for a year). Or, did I do something bad by wiring the blue wire?
Note that I actually do not know what the old switch controlled. We were told it was important for ventilation but we never actually heard any fans running until now.