Electric fan not working.....

[rokjeep]

So I'm at a loss. The aux. electric fan on my 1998 XJ is not working. I got a new relay and put that in...nothing. I checked the 40amp fuse in the distribution block....its fine. I connected the fan to the battery with some wire and the fan works that way.....so the motor is good.

The temp gauge has been acting funny the last few years. When crawling it would climb to 220* then jump to 260* but nothing would be boiling over and the overflow bottle is not full. If I rev up the engine for a while it will eventually drop back down to 220*. This started a few years ago but would only happen once or twice a summer. But last year it was rather frequent like once or twice a trip. For example, I couldn't get through the Box on the Con without it happening.

I thought it was strange the overflow bottle was empty when I started looking at it but its been dry since I got the jeep 7 years ago. I never thought anything of it but I have since topped it off to the full mark. There is no coolant in the oil, I checked that too.

Last summer I put on a new thermostat, fan clutch, water pump and flushed the radiator with water. Then refilled the system with the heater running on high. Temp gauge still did the same thing.

I'm wondering if there is an air pocket getting trapped in the thermostat housing causing the temp to spike up?

I put in a new temp sensor yesterday thinking that would help. I wasn't able to get the jeep to operating temp when running but the the fan will not kick on when I turn on the AC like it should. Very strange.

Any other ideas? I'm going to try to get the Jeep to operating temp today and see if that does anything.

Relay-good
fuse-good
fan motor-good


I'm at a loss right now.

 

[pokeyxj]

I have a 2001 that the fan does not come on by turning the AC on. It does come on when the temp gage shows 210. I thought maybe they changed something in the wireing because on my 96 the fan comes on with the AC.

 

[QUABOAG]

have you tried a new 16lb radiator cap? last year i was having temp spike problems similar to yours. come to find out, the electric fan was slowly dieing. i didnt realize it until it stopped spinning altogether.

 

[robsjeepxj]

Yes it will come on with the A/C when it reaches a high enough pressure as well as engine temp. The fan is triggered by the coolant temp sensor and I'm guessing the A/C high pressure sensor. If you unplugged the coolant temp sensor the fan should come on immediately, it will trigger a CEL code but at least you'll know that that part of the system works.

 

[dylan1650]

have you checked the ground at the fan plug? could be a bad ground... i would think the engine should be able to keep itself cool enough without the electric fan.... i didnt have an electric fan for like 2 years and didnt overheat once... did plenty of summer wheeling as well.. keep in mind i live in the northeast where it may not so much of a problem elsewhere..

 

[CaliXJ]

Check or replace the TCS at the back of the head. (this is the one the guage reads off of) Make sure your engine is actually reading what the guage says it is.. the two could be seeing different temps. Just a thought.

 

[Talyn]

Check or replace the TCS at the back of the head. (this is the one the guage reads off of)

His 98 doesn't have one there. There is just one sensor in the t-stat housing.

 

[O-Gauge Steamer]

Here is what I have done, in the past, to resurrect a fan:

Over time, carbon builds up in the motor causing several problems. Sometimes the electric fan starts running erratically, like it does not always want to start. Sometimes, when you turn them by hand, you will feel them "cog". By this I mean that it feels like it is going past notches. A DC motor should turn smoothly.
Here is how to reclaim a 97+ Fan Motor.
1. Remove the C-Clip and metal spacer securing the blade to the motor.
2. Remove the blade from the shaft. Tap the motor shaft LIGHTLY to get it off. DO NOT PRY ON THE BLADES, THEY WILL SHATTER!!!!!!
3. Remove the three screw securing the motor to the shroud.
4. There are several tabs that are bent down holding the backing plate. Gently pry these up to release the backing plate.
5. Blow out the built up carbon dust from the inside of the motor. As the motor operates, the brushes wear depositing carbon everywhere. This shorts the segments causing the "Cog" feel.
6. Gently clean between the commutator segments to remove the carbon. A very small scribe works well.
7. Reattach the backing plate by gently bending the tabs back into place.
8. Reattach motor to shroud.
9. Reattach blade.
10. Test.
This is a, usually, one time repair as the tabs holding the back plate on tend to snap off with repeated bendings as they are just thin sheet steel. It is also possible to just buy the motor by itself. Google the part number that is printed on the motor. It is a Bosch Part.

Hope this helps

 

[rokjeep]

Thanks for the ideas guys, so far no luck. I'm going to get my AC recharged and see if that has any effect on it.

 

[O-Gauge Steamer]

Have you "hot wired" the fan directly to the battery to make sure it works?

If the AC charge is low (or high for that matter) the compressor will not run so the fan will not run either. Unless the engine gets to 118F then the PCM calls for the fan to run regardless of the AC.

 

[rokjeep]

Have you "hot wired" the fan directly to the battery to make sure it works?

If the AC charge is low (or high for that matter) the compressor will not run so the fan will not run either. Unless the engine gets to 118F then the PCM calls for the fan to run regardless of the AC.

Yes I've wired the fan to the battery and it runs, so the motor is ok. I know the AC needs a recharge cause it blows hot air. But the fan should still work when the engine temp calls for the fan to run right even if the AC needs a recharge. I'm running out of ideas

 

[hubs97xj]

Have you tested the ground for the fan pigtail? Have you checked to see if you have 12V on the blue wire at the fan pigtail when the fan should be running? Have you independently (of the Jeep's sensor) confirmed the coolant temps? The last CTS I bought was off by nearly 30 degrees right out of the box.

 

[O-Gauge Steamer]

OK, you now know the fan is good. Take hubs advice and verify that there is battery voltage at the connector. Everything on our Heeps is controlled by the PCM supplying the Ground Connection.

I also agree with getting an independent temp check. Call around to the parts houses to see if any of them have an infrared thermometer you can borrow. Take the measurement at the T-Stat housing where the ECT Sensor is screwed in.

 

[rokjeep]

Thanks guys, I'll check the ground and the temp and check back.

 

[Sidewinder CC]

Here's a pic showing the ground location for the radiator fan. It's by the windshield washer fluid reservoir and the PCM.

 

[Sidewinder CC]

rokjeep,

Here's a test you can perform to check the radiator fan coolant over-temp system.

Testing of the 97-99 AC system to see if the fan and compressor clutch operate is similar to testing the over-temp system, whereas the engine must be running and the alternator must be on line.

Start by selecting AC on the HVAC control panel (any AC setting), then jumpering both the Low Pressure Cycling Switch and the High Pressure Switch using suitable jumpers. See Pics. Then start the engine. The fan should operate and the clutch should engage. If your AC refrigerant is low do not operate the compressor very long or it will shell out due to lack of lubricant.

Note: The 2000 and 2001 have a Dual Function High Pressure Switch that has 4 pin cavities. 2 pin cavities are for the fan and the other 2 serve the same purpose as the HPS in pre-00/01 XJ's.