1986 Civic Si Hatchback
The previous owner wired the radiator fan to turn on when the car starts. My question is how to unhook this setup and return to the OEM setup where the fan comes on automatically. Thanks for your help.

 

Wire a radiator fan switch like the image above (which should be for your 86 civic, fuse #)

 

Thank you, theYBLEGAL. Would this diagram the same for a car with A/C? Thanks

 

Yes it would, the ac fan is a different circuit