I have a 2003 Jeep Grand Cherokee and the cooling (electric) fan won't run, various opinions have been cooling sensor, thermostat, resistor?? Fuse is good I checked that. Hear is what happened the temp gauge went from 210 degrees(normal) up to 240,then the check engine light came on,A/C started blowing warm air, I was at an idle with A/C on. I turned off A/C and jeep and let it sit for awhile. Temp went back to normal,light stayed on. Drove Jeep for 30 miles, light went off and A/C blowing cold again.The fan does NOT come on when A/C is on and I think it is supposed to, any thoughts or suggestions would be appreciated I can't afford a mechanic right now. Thanks in advance, Trudy

The fan should work when the AC is on.

 

When the AC was blowing hot air this means it wasn't engaged. System could be low on refrigerant or the AC compressor could have gone off line because of the underhood temperature. Don't quote me on this but I think the compressor has a thermoswitch somewhere. When the compressor gets too hot, the switch turns off the compressor. I know my wagon will do this on very hot days and when I sit for 30 or more minutes with the engine just idling.

 

The fan has to have a relay somewhere. It may be failing.

 

Easy way to determine if the fan has not failed is to unplug it and then run 12volts to one side and ground the other. If the fan turns then you know it is not the problem.

lots of things run the fan.

if you hook the two wire leads as said, and fan turns on and runs, then you know its a sensor or relay or fuse

There is a thermoswitch on your block

there s a temp sensor on your radiator.

then you have the relays

usually the thermoswitch goes haywire first, or you have fuses blown. check under the hood in fusebox, and check in compartment block of fuses. there may be 2 fuses for the fans

Thank you both, I will check those things first and let you know what I find.

I think this fan is operated by the ECU. IUf this is true there is an aftermarket thermoswitch that can be purchased that just senses the temp of the radiator and turns on the fan.

 

It is not unusual for this type of fan control to go bad.