The only devices that I'm aware of that could cause a hum is vibration from the AC, the converter fan, the refrigerator compressor (if a regular house unit), or the inverter for the refrigerator (if a regular house unit). Obviously, if it's the AC, it should go off if you turn the AC off. If it's the converter fan, it should go away if you turn off all 12 volt devices. This includes lights. If it's the refrigerator, it should cycle as the refrigerator cycles on and off. If it's the inverter for the refrigerator, you'll likely have to hit the power button on the inverter itself to turn it off.
|