Howdy, I need a bit of help. My dad has a 2003 Jeep Grand Cherokee Limited (4.7L V8). It's again overheating when idle, if you turn on the heater and/or get back driving on the open road again the temp goes down. He went to replace the Fan Control Relay and found that he didn't have one! We cut a hole under the passenger-side headlight, nothing was there. I read hours worth of forum posts and articles saying if it wasn't there, then it would instead be 2 black cubes in the PDC box. But no high and low relays cubes in the box either. I finally found one, just one, post online that said 03 and 04 Grand Cherokee's do not have a fan control relay at all if they have the max cooling package (2-speed, 3-pin fan) that normally comes with the towing package, and that the fan is instead controlled by the computer. His Cherokee does have the towing package.

Is this true that he just does not have a fan control relay? In that case, he's thinking he needs to replace the fan. If that's not true, then where else could the relay be hidden?

Thank you in advance for any help.

 

Download a Factory Service Manual for his WJ from any one of many websites and check the wiring circuits. This rig doesn't, by any chance, have a hydraulic fan, does it? It is true the cooling fan is controlled by the computer, but should be running any time the A/C compressor is engaged. Even the ones with the single relay under the headlight is controlled by the computer pulsing it to control speeds.