Hey guys -

Lately my Jeep's electric cooling fan has been unnecessarily turning on as soon as the Jeep reaches normal operating temperature and continues to run after the engine has been shut off for about 20 minutes every time. After getting home from a drive yesterday and sitting for about 6 hours I went to start the Jeep and it was 100% dead. No dim dome light or anything at all. Just dead. My guess is that the fan just ran until the battery died although I'm not sure of this.

My question is: What would be causing my fan to run without the engine being too hot and continuing to run well after the engine has been shut off?

I'm planning on just disconnecting the fan since I see no harm in doing so. It's about 40 degrees max this time of year in the PNW and my cooling system and gauges work fine. If it gets hot I'll know.

Any help or thoughts on this would be greatly appreciated. Thank you -

Tim

 

There is probably an electrical short in. the wiring of the fan or a relay is stuck making contact. I would highly suggest you don't disconnect your fan. With a volt meter you can check to see if there is a short in the wiring.

 

Could the Temp Sensor for the computer/electric fan be defective?

It's the one on the front of the motor in the thermostat housing.

 

Thanks for the replies. I'll go by some electrical parts/contact cleaner and clean all the connections and sensors.

 

Well I just went out to jump start the Jeep and as soon as the jumper cables touched the battery the fan turned out. I unplugged the sensor from the thermostat housing and tried it again. No change.

Could you elaborate on why disconnecting the fan is a bad idea? What is it going to hurt? There's no point in even jump starting the engine unless I can get the fan to shut off, or I'll have to disconnect the battery every time I park it for more than 20 minutes.

Thanks -

Tim

 

Exactly why is there two differently driven fans on our xj's anyway?

Electric AND a mechanical clutch...never seen this before.

 

I'm having this same problem...couple weeks ago I lost heat . Replaced thermostat everything seemed good. Then I came home one afternoon and the electric fan was running after I got out. I disconnected fan and waited a few hours....went out plugged it back in and it started running again. I've left it unplugged, just so it didn't drain the battery...and time to time ill plug it in and check....it doesn't matter....hot cold....it runs.

Thing that really sucks is I got the idiot light temp gauge....that doesn't work anyway...and I've pulled the dash cluster...checked, swapped out bulbs I knew that worked....nothing. light wont even come on when you put key in acc. Position as it should.

I'm guessing as stated its a relay stuck open...or temp sensing gauge ...hoping for the temp sensor since its thread off....thread one...and auto zone has it in stock for like $12.

 

I had the same problem on my 1998 Cherokee classic every time I would dive it the electric fan would stay on until it killed the battery or I unplugged the fan. I checked everything I could think of in the end I ended up hooking the fan to a toggle switch in the cab so I can turn it on and off manually. It has worked very well for me and I have never had any problems with over heating as long as I remember to turn the fan on. It was a cheap fix only costing me around 7 dollars for wire connectors and toggle switch.

 

cooling fan relay stuck maybe?

 

http://www.lunghd.com/Tech_Articles/..._Diagnosis.htm

 

that was going to be my guess, swap the fan relay with another one see what happens.

nathan
99 xj dual batteries, 136 amp alt, york oba