What really ac fan or coolant fan?Is the fan on? Some times thy just get stuck on hit with a wrench.

OK by your name its a 94 civic and you have a b18b in it I am assuming you no longer have ac or never did?

So in you fuse box(take it apart) their is a Black yellow,Yellow green and a Black red wire all in the same connector find it.From what I can see its the one with 7 wires going into it its brown next to the battery.

The yellow green is the ground for the control side of the really 2 things ground out this wire.One the engine coolant temp switch and the ecu.

Possible causes
1 Engine coolant temp switch stuck on(unplug it see if the really turns off)It has one green wire on black wire
2 the ecm is wigging out(unplug it see if the really turns off)
3 The yellow green wire is shorted to ground( just run a new wire and switch it so you can turn on the fan every time you start the car)