2008 forest river, sierra. I can turn on all lights in trailer and if I shut off one light I get a noise from behind breaker box. The sound is like air being let out of a tire. If I have only some lights on and I open frig. dr. it sounds again. There is no set way of making it happen it just does. I have tried shutting power to trailer and shutting down breakers to know avail. Anyone have any ideas. I concerned about safety.
If your power converter is behind your breaker box, it could be the converter fan operation you hear as K Charles posted. The fan will operate when the converter heats to a point that it requires cooling. It may take a minute to start after turning on enough devices/bulbs for it to require cooling.
Some develop sort of high pitched squeal or hiss to them. I had that happen on my last trailer's converter after only a couple years old. I imagine it needed to be replaced to eleminate the hiss, but I traded the trailer. (wasn't the only reason)
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