Does an on/off switch still means on/off when positioned horizontally?

I'm working on a custom piece of hardware where a fan is turned on and off automatically. The user can override the decision of the automatic system through a switch. Activating the switch when the fan is on will turn it off, and vice versa.

Is it a valid choice to use a toggle switch (see the image below) for that, if the switch is positioned horizontally (i.e. the handle facing either left or right)? Or should I use a button switch instead?

Those switches, when put vertically, are usually associated with on/off actions, where the handle pointing upwards means something is turned on, and when it points towards the floor, it means the thing controlled by the switch is off—although, in some countries, the opposite may be true. In my case, however, the actual position of the handle doesn't mean anything about the current state of the thing under control; instead, the switch acts only as a way to change the state.