On a 1994 Saturn SC2 why would the cooling fan not come on unless you hook it up direct if you just changed the coolant temperature sensor?
Have you checked the cooling fan relay? ? This is the child's wooden block size relay installed in the fuse/relay box in under the hood. If it is bad the fan will not come on even if all the other sensors and components of the system are functioning. Also, This cooling fan relay draws a lot of amperage which causes it to heat up. On my '92 SC2, I have learned that the contacts of the relay have become so hot from the high current they carry that the fuse box sockets overheat and deform. It became necessary for me to open up the upper and lower halves of the fuse box and install new conductors to restore good contact with the relay pins. If you find that your cooling fan relay pins are discolored and the plastic housing is slightly deformed around the pins, you are likely haveing a similar problem. For a while I was able to just slightly twist the pins of a new relay using a pair pliers so that they would make tighter contact in the deformed sockets of the relay box. Hope this helps, JB