I change thermostat radiator cap I flush the radiator and it still geting hot. I noticed something the fan don't turn on until it reaches the line in the half of the temp. Gauge and only is on for 40 secs. Is it a relay or the fan it self.

Two things to check:

1. Make sure you do not have an air bubble in your cooling system. Easiest way is to park facing uphill and let the car cool off. Remove the radiator cap, start the car and let run until the thermostat opens. If there are air bubbles in the cooling system the should be forced out. Top off fluid.
2. Are you sure that the cooling fan is running? When the car is getting hot, open the hood and make sure the radiator fan is actually turning.

sound like the impelled in your water pump may have failed. Or your system is air bound. Try to open the rad cap when its cold and let it run and see if air bubbles come to the top

Step 1:

When the thermo..do not work,there is an easy way to know...let the car running for at least 10min..turn it off..touch upper and lower hoses...if any of them is hot and the other is cold...thermos..not working.

Step 2:

check if fans activate when it reaches normal temperature, if they dont,replace fan switch at the botton of radiator,or check if the fans are burned.

Step 3:

you can flush the radiator by the usual way,but it will not unclog any cell of radiator...you must send it for service... but before u do it..do the cheap and easy staff...by the way...that car operate with a different cooling system...thats a closed pressured...so changing the cap of the reservoir helps ...since it has some valves that goes broken when is not change...hope it helps...

if you turn on the ac the other fan should come on, However I don't believe that will cure the problem your having since having the ac fan and the ac turned on pretty much cancel each other out, Putting a new thermostat on Just allows the thermostat to open and close at the set temp that's on the thermostat , Not really fixing the problem, ( unless the thermostat is stuck in the closed position would replacement of it help ) what I would suggest is to completely flush your cooling system, and add new antifreeze, antifreeze like oil breaks down, other heating problems can be caused from the car not tuned properly, check the timing , and components associated with the car running properly, ( plugs, rotor and cap, spark plug wires, )

DID YOU BLEED AIR OUT THE COOLANT SYSTEM.TO BLEED COOLANT SYSTEM, FILL THE COOLANT SYSTEM THROUGH THE RESERVOIR TANK OR THE RADIATOR UNTIL THE FULL COLD MARK IS REACHED.BESURE TO USE 50/50 HALF WATER AND ANTIFREEZE.YOU CAN BUY ANTIFREEZE THAT IS ALREADY PREMIX 50/50.AFTER ADDING ANTIFREEZE TO RESERVOIR OR RADIATOR FILL RADIATOR TO FULL MARK OR IF YOU DONT HAVE RADIATOR CAP ON RADIATOR POUR ANTIFREEZE IN THE OVERFLOW JUG UNTIL COOLANT LEVEL STAY THE FULL COLD MARK.WAIT AWHILE UNTIL COOLANT LEVEL STOP DROPPING.NOW INSTALL THE RADIATOR OR OVER FLOW JUG CAP.START THE ENGINE AND ALLOW IT TO RUN UNTIL NORMAL OPERATING TEMPERATURE IS REACHED AND THE UPPER RADIATOR HOSE BECOME HOT.STOP THE ENGINE AND OBSERVE THE COOLANT LEVEL IN THE OVERFLOW JUG. THE COOLANT LEVEL SHOULD BE AT THE FULL HOT LINE.ALLOW THE ENGINE TO COOL UNTIL THE AMBIENT TEMPERATURE IS REACHED THEN CHECK THE COOLANT LEVEL IT SHOULD BE AT OR ABOVE THE FULL COLD LINE.ADD MORE COOLANT IF NECESSARY. WARNING BECAREFUL WHEN OPEN THE RADIATOR CAP OR JUG OVER FLOW CAP.USE A LARGE RAG OVER THE RADIATOR CAP TO KEEP FROM GETTING SCALDED.OPEN RADIATOR CAP A LITTLE AT A TIME TO KEEP FROM GETTING SCALDED.WAIT UNTIL ENGINE COOL DOWN BEFORE OPENING RADIATOR CAP OR OVERFLOW JUG CAP.WEAR SAFETY GLASSES.

it sounds like one of several problems radiator needs flushed , water pump is bad or going, thermostat is bad, pin hole in one of the hoses, cracked head, hole in radiator, hole in heater core.if core is leaking you will notice water on the floor inside the car on pasenger side. if radiator has hole when you fill radiator with coolant it will leak froom fins sometimes only when hot. thermostat bad your car will read hot and or cold always. if stuck open cold, if stuck closed hot, after about 15 20 mins of running engine will cause radiator to boil over to over flow tank.never open radiator cap when engine is hot :) burn hazard.if pump is bad or going will notice gauge reads hot intermittent or always. will boil in to overflow tank. if head is cracked will notice water comming from side of engine block or in oil when you change oil. if radiator needs to be flushed will notice scale or gunk on radiator cap
(if you think you need help or do not have tools to perform please take to a machanic)

Assuming they checked the controls under the dash and everything is working, lets try to bleed the air from the cooling system. An air lock in the heater core could stop it from getting warm. You will need a gallon of antifreeze and a jack to raise the car. Here we go: remove the radiator cap. Set the parking brake, transmission in park, block the rear wheels. Jack up the front of the car so that the radiator is higher than the engine. Start the engine and put the heater controls on the hottest setting but don not turn the heater on. With the engine running, look in the radiator, the coolant at this point should not be moving, or flowing through the radiator because the thermostat has not reached the temperature required for it to open. If the coolant is flowing at this time, then the thermostat is open and should be replaced. Let the engine warm up and watch the coolant level. When the thermostat opens up, the coolant level will drop, and you will be able to see the coolant flowing or moving in the radiator. Add enough antifreeze to fill the radiator ack up. The coolant level will probably drop again, Add more coolant as required. Repeat this process until the coolant level stabilizes and no longer drops while there is flow or movement of the coolant. Replace the radiator cap and lower the jack. Turn the heater on. If the problem was an air lock in the heater core, you should now have warm air blowing from the heater.. Something else to observe is the cooling fan for the radiator. If the electric cooling fan was running the whole time the engine was running, then the switch controlling the fan is bad. The fan should not come on until the radiator is hot. If it runs all the time, the coolant won't get hot enough for the heater to work. Let me know is this works.

Heres a couple of things you can check. Start your car and remove the radiator cap,(before it gets hot mind you) when it reaches norm operating temp, look inside radiator to see if water is circulating. If its not moving, its a bad water pump. Also, youre hoses should never collapse, if they collapse when they get hot maybe you need new hoses? Finally, if those dont work, flush out your radiator. Open the bottom cockpit and use a garden hose and let it flush out the system while the car is running, about 10 mins should do the trick. If the radiator looks clean inside then it doesnt need flushed.

Radiator Fan Control Relay Switch. I bet your electric fan doesn't run?

The problem with these jeeps is that the older they get the more clogged the radiator geats.
The radiator in the Cherokees are only a single row of tubes.
You can try to flush out the radiator, but replacing it with a heavy duty type is probably a better option.
Your car is not getting enough flow to cool down the engine.
Also you want to check that the electric fan is coming on. There is a coolant sensor in the radiator.