Aux Fan Problem

I'm having trouble with my aux fan. I noticed it was turning very slow last week but I figured that was because the battery was shot. I replaced the battery and it didn't work at all. I changed the relay and it worked great for about 3 minutes. Now it doesn't spin at all. This was all with the AC on. What should I check next?

98 4.0L AW4 Limited

The AC was on or the Compressor was running? It should only run if the compressor is running or the engine is hot as hell.

To save you from hunting for the thread, I have copied my thoghts here for you. Actually, it will most likely be the same for pre 97s, I just have not taken one apart...

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, or they will run slow. 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.

Thanks for the replies. I didn't even check to make sure if the compressor was cycling on and off. I'll check that out this weekend.
I'll also look into to tearing apart the fan is the compressor checks out.

the aux fan on my 99 xj died this summer in a very similar way. i noticed climbing temps at idle during hot weather. i replaced the mechanical clutch fan seeing as the xj had 225k and it looked origional. still had the problem and one day i noticed the electric fan wasnt spinning with the ac on. it was 90+ out with the ac on and a few miles of idling stop and go traffic and the gauge bumped into the red. a sharp rap on top of the fan housing started it to spin again, although it seemed a little lazy. pricing out replacements, i found the motor alone cost more than a brand new fan assembly.

Costs for replacement depend entirely on the country of origin for the part. I have seen motors for as low as $20.00 (Chinese) and as high as $140 (German). From Jeep, a complete assemble is something like $270ish.

You get what you pay for. The factory unit is quality, German parts. The El Cheapo units are Genuine Chinese Junk.

The funny thing about Chinese parts is that they build to the quality level mandated by the requestor. If you request a Bosch level of quality, you get it. If you request that the thing mostly looks like what it should, then that is what you get.

Our problem is the idiots getting the things made, not the folks on the assembly line...

For me, I pay the extra and get parts that will last. In the long run, they are usually less expensive.