Electric fan wont kick in jeep over heats replaced thermostat and two sender units

Sounds like your cooling fan relay is bad the jeep grand cherokees are known for this, first thing i would do is unplug the radiator cooling fan and run 2 jumper wires direct from the battery to the fan connector if the fan kicks on your fan motor is good and the relay is bad, if the fan doesnt kick on replace the fan motor with a new unit, the cooling fan relay on your particular model jeep is located under the passenger headlight and requires you remove the front bumper to replace it, however some people cut a small hole under the headlight to access the relay the faster way but if your not to keen on cutting holes in your car remove the bumper and replace the relay if the fan checks out and you wont be overheating anymore...