I have a WJ 04 with a 4.0. It was recently overheating while in idle. The fan proved to be bad and was replaced. This fixed the issue for about a month but it once again started overheating. The fan proved to have gone bad and wads replaced under warranty. The new fan was tested and was working fine but will not come on in either low or high range. I was told there was a radiator fan control relay in addition to the PDC relays for high and low speed function. I cannot locate this relay. I was told its under the passenger headlight. Since i did not find it i went to a jeep dealer who printed of a replacement instruction indicating it was either under the drivers headlight or near the air intake snorkle; apparently it was relocated mid year in my production line. I CANT FIND IT ANYWHERE! It is not in any of the three locations indicated. My AC comes on and off normally so I know my high low pressure switch must be working. Both relays in the PDC were replaced and i cant find any blown fuses. I then replaced the coolant temperature sensor to no avail. Can someone tel me if there is another place this might be? Is this something that may be controlled by the PTCM?

 

it is under passenger headlight and then there is a plastic part the headlight is held by under it, i had to cut a hole in it to get to the relay.

 

It's my understanding that the pulse-modulated relay found under the headlight was replaced by 2 relays in the PDC in 2003 or 2004 because of the increased failure of the original design. The PCM DOES read the engine temp from the sensor at the thermostat to control the fan, but instead of pulsing the current to create the low speed, it uses a constant signal to a low speed relay. I think the later fan has 3 wires instead of 2, but I'm not sure about that.


The fan should be running on high anytime the A/C clutch is engaged.

 

cycles on/on by demand from refrigerant high pressure switch.

 

Well excuse my wa!

 

In my model the AC switch does not come off the line. The entire line has to be replaced. Which means purge and fill for my AC. The dealer does show a control relay in the repair manual but i cant find it.

 

In my model the AC switch does not come off the line. The entire line has to be replaced. Which means purge and fill for my AC. The dealer does show a control relay in the repair manual but i cant find it.

 

The AC is not the only control for the high speed fan. If coolant temperature exceeds a preset amount above normal high speed fan relay will kick in. In normal operation w/o AC running fan will run on the lower speed.

 

Agreed, however this is not happening. The dealership assures me the relay is part of the circuit in my model but i just cant find it. I was hoping that someone might have experienced this and knew of an alternate location. Its frustrating to say the least.

 

2004 GC.....2 relays in PDC (fuse)box between battery and coolant reservoir. The relays are the ones closest to the firewall. They are marked.

 

Two relays in PDC both replaced: no change
Coolant temp sensor replaced: no change.
Fan replaced: no change.
I am trying to locate the Radiator Fan Control Relay.

 

you won't find it on a 2004 because it doesn't exist! All you have is the 2 relays in the PDC.

 

I was just going to say that! Your pic shows the earlier relay and that's found here;

 

I got this from the Jeep dealership.

 

***REPEAT**** 2004 JGC does NOT use this PWM relay if you have the 2 fan relays in PDC. What is crazy is the FSM shows this relay behind drivers side headlight....I can assure you it does not exist although the plug and wiring harness is in place!