Good morning, as stated above, I’m wanting to install a new light/fan switch w/dimmer and fan control, however our house was built in 1925 and has no ground or nutral at the box, only single power wire in and single out to fan. Is there a safe way to do this short of rewiring the house? The switch I purchased has a wire for the light and one for the fan, would I be able to split that power wire to both, or would it, if doing so, control both no matter which switch was activated?
There are some other possibilities (e.g., one wire of a knob and tube connection), but unless that wiring is really old you likely have a switch loop. One way to tell: if the two wires connected to the switch go out of the box together in one cable then it is a switch loop.
Assuming it is a switch loop and that you have cables and not conduit, you really only have a couple of choices:
Fan/Light with Remote
Many fans with light kits also have, either included or as an option, a remote control. These are somewhat standardized, with a box that mounts on the fan (i.e., in the ceiling) that connects to incoming hot & neutral (which you should have from the existing light) and to two separate switched hots (fan and light) and neutral on the fan. You get a remote control (good: if if it is a good one then it can control fan on/off/speed and light on/off/dim – exactly what you want; bad: it can get lost just like a TV remote control) and typically put that in a little holder on the wall next to the switch. The wall switch doesn’t change at all and turns everything on/off together, so you use the remote most of the time to adjust the fan and light.
I don’t like these types of remotes, but in your case they may make a lot of sense.
New Wires
You will need 4 wires: hot (which you already have), two switched hots (you have one right now) and neutral. If you have conduit then this is easy. But most likely (unless you are in Chicago or New York) you have cables, so that means figuring out how to install a new 4-wire cable (technically 5 wires because modern cables include ground as well) between the switch box and the ceiling fan/light box. That may involve breaking and fixing (patch/paint) things (wall and/or ceiling), and may be fairly easy or a lot of work.