Electric fan keeps coming

2000 XJ 4.0l, AW4, 174k

Electric fan keeps coming on even with mild temps and A/C off. Water pump and thermostat were replaced about 6 months ago. It’s not overheating staying around 210 degrees but it hasn’t gotten hot where I live yet. Also, noticed the AC is not blowing very cold.

Searching lead me to check the fan clutch. With the rig hot (electric fan kicked on) I shut it off and immediately tried turning the fan and it turned with only slight resistance. Then I tried stopping the fan while running with a rolled up newspaper but it did not stop or even slow down. Could it still be the clutch or should I look somewhere else? Thanks.

The electric fan coming on is controlled by thermostatically controlled switch mounted in the coolant flow. Not sure about your vehicle, but I seem to remember it is mounted on the thermostat housing.

Once you find it, unplug it. If the fan still comes on, there is a short in the wiring. You can test the switch with a voltmeter on the car with the motor running, or with an ohmmeter with the engine off and the connector removed.

My best guess is that you have a switch that is going bad.

The dash gauge is really inaccurate. Try to check with an ir temp gun or use an obd scan tool or something other than the gauge. If it's still low I'd go to a junk yard and pull the clutch out of a zj and put in yours. I did it and I can hardly turn the fan with it hot and off.


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Thanks.

Can I edit the subject? I kind of forgot a word...

old_man said:

The electric fan coming on is controlled by thermostatically controlled switch mounted in the coolant flow. .... it is mounted on the thermostat housing. ........

Click to expand...

This much is correct.



1997-2001, the e-fan runs as necessary based on coolant temperatures.

With the engine idling, if you unplug the wire harness from the Coolant Temperature Sensor (CTS) the e-fan will start and run continuously after about 5-10 seconds. This is normal, this is the CTS fail-safe mode, and proves that the e-fan relay and e-fan wire circuit is functioning correctly. The Check Engine Light may turn ON, but this is normal, and it will turn OFF by itself after plugging the sensor back in, and driving for a bit.

If the e-fan does not turn ON with the CTS unplugged, you have a problem.

Started it up after sitting all night and let it idle until it got to about 210 degrees then the electric fan came on.

With ir temp gun I get a max of about 214 degrees (thermostat housing). With the CTS unplugged the fan came on as soon as I turned it over.

I feel that it is the a/c switch telling it to come on, since it works as it should when unplugging the cts.


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The e-fan comes on at about 215*-218*. The A/C pressure switch has some influence also.

The fan clutch is a normal wear item for routine maintence. If you think it is weak, install a new one.

Fan relay stuck on?