98 Jeep wrangler, fan/air won't cut off

2.4L so did you first idle it to get over heat,220f so it can kickon,
scanning the ECT s,proving it hit too hot,, per SM>??
the key here is what, a real schematic,
and a simple voltmeter
some jeeps also have a modulated fan.(and driver for it)
fuse 4, PDC good. tested?
it goes to fan relay , contacts and then to fan motor circuit breaker
no air pocket on top of engine,making, ECT lie?
i the pcm sees ECT overheat
it puts 12vdc across the fan relay coils
if not the wire there bad,cut or pcm bad.
the PCM pin C2-p17 LG wire goes to relay pin 4
he PCM grounds this pin (using a transistor)
the relay closes, fan turns on.

when you turn the key to the run position do you hear the fuel pump run? do you know if you have spark?

Check the fuses or the blower resistor that should be located on the passengers side under the glove box near or on the fan housing.

It may be a relay problem. From the controls on the dash it should lead you to the components behind the dashboard. Check if the connections are OK. I am unsure if the relays are found there, but inspect the relay at that area or under the hood.

check the coolant temp sending unit it can give the same kind of problems a manifold air temp sender will.

on my grand, there is a variable resistor that controls fan speed. The wires feeding the resistor melted down. Turns out it was a very common problem for the year I have. I would look there first and eliminate that possibility. The power should be frigging fat wire about 8 or 10 gauge and is fed from one of your electrical junctions under the hood. The fusible links can look ok and actually be faulty, so test for the voltage and/or resistance at these points. If It is still down, and you are able to remove the fan, do a simple check to make sure its able to spin freely.

Your vehicle has 2 ignition wires that you can put back to factory, and start the vehicle.
The wires you are looking to put back together are (blue) and (black/orange) - and found under the D/S dash. (ignition harness) They will be larger in Diameter than the others.
They were cut to install the security system. They go into the "brain" and out the other side. A relay inside the BRAIN is most likely failing.
If you no longer want the alarm installed, simply match up all of the factory colors. Use crimp-on ****-connectors for secure connection.
Let me know if you need more help.

Try this disconnect the heater hoses from the heater core use a hose to backflush the core. Then reconnect and try again.

Clean the drain plug by the Battery under the hood, It's clogged.

Yeah, I would go up hill or pull away from a stop and the A/C would cut out and then come back once my speed was stabilized. It was a vacuum hose leak !! This mostly affected the upper dash blower fan.