02 jeep grand cherokee not running when temp gets high. replaced radiator fan relay

Could be either one, but usually its the fan motor.
You can run a wire direct from the battery to bypass the relay to see how fast the fan is able to run. The connector on the fan relay can become damaged too.

Hi Al, I'm glad to help!

Three possible causes: (1) The high speed circuit in the radiator fan motor could be defective. (2) The high speed fan relay Could be defective. (3) It possibly may have a wiring issue. I've seen at times where you can wiggle the fan motor connector that's mounted on the fan shroud and the motor will kick on. If this is the case then replace the hole assembly which is a motor and shroud assembly. Hope this helps and have an awesome day.

Fan relay is located under pass headlight. Remove light assembly, use 2 1/2 " hole saw to drill hole in plastic housing ,3"from back wall, 3'' from left side.This will put you right over relay. Unscrew two bolts,replace. Relay was $40.... dealer wanted$350 to remove front bumper to replace it.

check the thermostat or your radiator might be stopped up

Check the coolant temperature switch. You should have 12V on one side of the switch. If you jumper the two wires in the switch connector, your radiator fan should run with the ignition switch on. If it runs, replace the coolant temperature switch.

Check the fan operation by disconnecting the fan wiring. Using the battery use a set of jumper wires to see if the fan runs directly off the battery.

Disconnect the fan plug and hot wire it to the battery if the fan dosen't run, replace it. Otherwise, check the relay. The system operates by the temp sender sending a signal to the computer that activates the relay that turns the fan on. Fan should also come on with A/C.

usually the engine relay or cooling fan relay..!

Check the wiring from the relay to the fan motor, and check the wiring from the fuse block. Basically check all wires that supply power to the fan motor, use a volt meter. Fan Relay (behind headlight, under battery) on the 2001 GC 4.0L are a piece of ****, I change mine almost yearly. The problem is their location, a high heat area prone to the elements. I understand that 2002 and newer, the location was changed and the problem solved. Relay might close the circuit when cold or at reasonable temps, but might open a circuit when it heats up, causing the problem.

Have you tested the fan sending unit on the engine? disconnect that and if the fan runs (Key on) that is most likely the problem.