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Elec fan on driver's side

xjintx

xjintx

NAXJA Forum User
Location
Eddy, TX
OK, I appologize if dumb question but not dumb to me ;)
I just bought a 2000 4.0L new to me. I also have an 87 2.5L

The 87 has just one radiator fan the 2000 has two :)

The driver side elec fan was disconnected when I bought it... I figured fan burnt out as it would not spin by hand.

removed that fan and it spins freely was probably just hitting. Put 12volts to it and spins fine.

My question is how does the 12vdc get to the plug? With engine running nothing at plug... I assume something like AC or heat activates it? maybe thermostat or something?

Any help is appreciated!!!!
 
XJ4MEPLZ said:
When the ac compressor is running the electric fan should get power. it should also turn on when the engine starts to overheat.
Click to expand...

Not on his 2000.

On the very late models the PCM controls ALL operation of the auxiliary fan. It no longer operates when the a/c compressor cycles.

Test: unplug the CTS--coolant temperature sensor--in the thermostat housing and the auxiliary fan should run at that time.
 
man... THANKS I will try when i get home. If it still does not come on is it as simple as the wiring? Can I check for a voltage with it connected if not working or no voltage is it as simple as a bad CTS?
 
When you unplug the CTS the PCM should turn on the fan.

If the fan doesn't run, and you have already proven the fan good when you jumped it direct, then you will have to determine where the open is in the circuit--wiring, relay, fuse, bad PCM.

Post up what happens when you unplug the CTS with the engine running and let us know, then we can go from there.
 
OK, sorry for lateness but been traveling and just got back to it.
If I unplug the sensor the fan does in fact turn on :)
So may I assume the sensore is bad or am I not waiting long enough for the engine to get to the mention 222 degrees.

I am idleing engine with AC on but it's staying at 210 degrees and no fan.

WEIRD coincidense but now while doing this I have a check engine light... my son has my OBII tester so guess I need to head to Autozone.

Should I buy the sensor????
 
xjintx said:
...WEIRD coincidense but now while doing this I have a check engine light... Should I buy the sensor????
Click to expand...

Pulling the CTS wire plug will trigger the CEL.

The CTS is about $35, and they can get sluggish or even fail. Buy one and consider it a preventative maintenance item.
 
Yep CEL went out on my return from AutoZone. I ordered the sensor and I hope that is a fix. My engine is by no means overheating but I'd like the additional fan.

Is it safe to say that after I replace the sensor it will come on when >220 degrees even without running the AC?

Thanks for the HELP!!!!
 
Nothing is broken...You said your temp is not going above 210...


From the Factory Service Manual..

Electric cooling fan 4.0L:
With or without A/C request the electric fan will come on only when the coolant temperature is at least 106° C (223° F), and will remain on until the coolant temperature drops to103° C (217° F) or below.
If you think your gauge is wrong compare it to the reading you get from your OBDII tester

you should feel good that your Jeep can idle with A/C running and your cooling system is maintaining 210 degrees without the help of the Electric fan...I'm betting that if you wait long enough, with the hood closed, you will here the fan kick on.


​
 
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