There are very few items, where you will not realise what they did by turning them off. There are so damp course systems, not sure how they work, and my father-in-law had a switch marked immersion heater, which he knew had been removed, in his kitchen, so he turned it off, and it transpired it powered the pumps for the DHW solar panels, only found that out, when he had smart meters fitted, and they did not re-light the pilot flame in his boiler, it seems the whole reason why his electric bills went down, was due to using gas instead, the solar was useless.
But in the main, if it seems to do nothing, leave it turned off. I had one in my back kitchen, seemed to do nothing, I will guess some years back it supplied a shed, but now converted to supplying an outside socket. The shed cables found were twin and earth buried in the garden, no way would I reconnect those.