If it is silent, that would be normal. If in the outside, it must have a slight noise. See the vibrations of the glass, wooden, plastic, or grill. See for balance. It must be tilted downwards. At the pcb board, it should have switch labeled as manual switch. That will switch on the device and you open indoor flap. When the remote is locked, you simultaneously push the temperature up and down buttons for few times. That will unlock the unit.