OK as I vaguely remembered the 2003 KJs have a different means of turning the radiator fan on compared to the latter models.
There are not radiator fan relays in the relay box under the hood.
This fan of yours only has one speed and it is powered by a single, large robust relay located somewhere in the engine bay...other members here could help with its exact location.
Fuse #2 40 Amps in the box under the hood supplies +12 volts to pin 1 on this relay via a Dark Blue/Pink wire. Ground is supplied to pin 3 on this relay and also to the fan via a Black/Orange wire.
The output of the relay supplies +12 volts to the fan from pin 2 via a Yellow wire. The relay is energized via a Light Green wire on pin 4. This Light Green wire goes through pin 5 on Connector C103 to pin 17 on connector C2 of the PCM. The PCM activates this Light Green wire when the AC Pressure Transducer is good or the Power Steering Switch is good.
So you need to check that Fuse # 2 is OK, Connector C103 is clean and firmly connected, the Black/Orange wire is at ground with reference to +12 volts. So measuring with a voltmeter you need to find +12 volts on the Yellow wire at the fan while the Black/Orange wire on the fan is at ground...all this when the AC is turned ON or supposedly when the engine is hot although this later point I do not see in the wiring diagrams?
The 2003 KJ Service Manual can be downloaded here....has a theory of operations section while the Wiring Diagrams in section 8W gives you the circuitry and also a Locations section which shows you where various connectors are located as well as the ground point G112. Main logic page to refer to is: 8W-30-23
KJ Service Manuals:
Index of /manuals/Jeep/KJ