Why won't it work?

[bdahlg]

91 cherokee 4.0L 4WD
My cooling fan wasn't working. When i jumped it, still nothing. Went do to advance autos and picked up another one. Now it turns on but not when its supposed to. I believe its supposed to kick on when either the A/C is on or when it reaches about 220. When she is above operating temp (needle is visibly over 210) and i shut it off, it comes on when when i turn the ignition key and will remain on until it reaches operating temp, then will shut off. It WILL NOT turn on unless i repeat the procedure; she will over heat when the engine is running. Jumped the relay (hot wire all times) and it comes on so i know its getting some juice. Took off negative battery cable for 12 hours to reset the ecu, but still did the same thing. No codes.
Any help would be great.