Cooling Fan Problem

when i changed the thermostat in my 2000 Malibu LS I didn't bleed the system and the car overheated. But for some reason the cooling fan won't turn on when it should. When the weather is warm or sitting in traffic I have to turn on the a/c so the fan turns or else I smell anti-freeze.
I've gotten the car up to operating temp and waited for the cooling fan to kick on but it won't. The temp just goes higher and higher. Also when I turn on the a/c for the fan to kick on the fan doesn't sound as strong as it should. Both fans turn on but it sounds weak.
There is also a sloooow leak around the coolant temp sensor threads but I seriously doubt that has anything to do with the cooling fan. So can anyone make any recommendations on how to troubleshoot and fix the cooling fan problem? Also anyone know how I can "jump" the terminals so the fan stays on all the time? This is only a temp fix so the car doesn't overheat in traffic. Thanks in advance.

On newer vehicles the on board computer typically controls the relay that provides power for the cooling fans, so I would locate and remove the relay, check the relay coil with a DVOM, and check the relay sockets at the appropiate locations for power etc. OH and it might be a good idea to locate and check the fuse.

On the side of the relay is a printed electrical schematic that is handy for trouble-shooting.

Mike