Cooling question
 

Hello everyone, I've been doing a bunch of reading and I am sort of perplexed how this system is supposed to work.
From what I've read, it seems that operating temps should be between 200 and 220 with the E fan kicking on at 218 or if the AC is turned on.
I have found that when I am out trail riding, my temps will creep above 210 and it worries me, so I turn the AC on and watch my temps come back to around 200. Its crazy that running with AC on while trail riding keeps my temps lower.
First question is, if running hotter then 220 is not good, why the heck does the E fan not turn on until 218?

I am curious if I could splice into the E fan with a switch and resistor so I can turn it on without AC whenever I would like and the resisitor should keep it from back feeding my switch when it kicks on while using AC.
Second question is, does this sound feasible?

I couldve been reading misinformation and maybe it is ok for these motors to be above 220 degrees, that just seems quite hot.
I also bought a Bluetooth scan tool that I can get live data to my phone that I have been using to watch my temps.

Thanks in advance for your advice, Sincerely, Dan

It's very likely, given your description, that your mechanical fan's clutch is worn out.

As long as everything is working properly (i.e. the temp climbs, e-fan kicks on, and temp comes back down), I wouldn't worry about it too much.

With that said, many people, myself included, have wired in an electric fan override switch. I like to leave the fan running when I'm out wheeling.

The way to do it is slightly different than what you describe. Not sure if you're mixing up resistors with diodes, but you'll need to use a second relay to create a new circuit for the override switch.

The OEM circuit puts constant voltage to pin 85 (switching coil) 100% of the time, and the switching action is controlled by grounding pin 86. The grounding is switched in the PCM via logic using the coolant temp sensor and AC pressure switches. It is possible to just T off of the wire between pin 86 on the fan relay and the PCM and run it to another switch to ground, however this will throw a check engine light because the PCM will see voltage on that circuit when it is not expecting it. To avoid triggering a CEL, a second relay needs to be used such that when the power goes through either the OEM fan control circuit or the override circuit, it is isolated from the other.

Check out this thread for a better explanation: https://www.cherokeeforum.com/f51/ri...-e-fan-212243/

Cruiser, is there any way of testing it? I know the mech fan is always spinning.

It's not a science.

With the engine warm and ENGINE OFF, spin the mechanical fan. There should be a fair amount of resistance and the fan should not keep spinning after you let go of it. . It should certainly not spin freely.

Cruiser, thank you, I'm gonna take my daughter to school so I will take the jeep so I can test the clutch while warm.

XJ limited, amazing write up! I appreciate the link and I feel the same as you where I would like to be able to manually turn the E fan on while wheeling.

Definitely wanna make sure everything is working as it should. I appreciate y'alls input and will get back later with my fan clutch findings. Thanks again!

You've got this!!

Cruiser, color me impressed! Fan clutch is gone. Just got home from taking my daughter to school and the fan spins freely.
It is amazing to me that you got that from that write up I did! Looks like I'm gonna run to oreillys and get a new fan clutch to put on. Thank you very much!

New fan clutch is in. Got her up to temp and couldn't free spin anymore. Thanks again cruiser!

One last question, what temp is to high for these engines? Just out of curiosity.

218+ ???

IIRC, the e-fan doesn't kick on until about 221* or so on the 2000-2001 year Cherokees. With the new fan clutch installed, you should definitely notice it blowing some air on a warm day after you've been stopped in traffic for a bit. You'll hear it roaring a bit as the engine speed climbs.

I'd definitely second the recommendation to wire up an override switch for the fan using those instructions linked above. It'll keep your transmission temps lower offroad as well if you have an automatic.

IJM, thanks for the reply, that's crazy the E fan doesn't turn on until 221. I will definitely be following the wire diagram provided to hook the E fan up to a switch, especially for when I am trail riding.
It was 87° here today and i definitely noticed you can actually hear the fan while in traffic now and my temps stayed right at 200, which it hasn't done in a long time lol. Super happy I found this before it gets to hot down here!

I thought it was 208 or 218. I could be wrong.

My trick:

https://cimg0.ibsrv.net/gimg/www.che...decdd621d5.jpg

The 2000 FSM says on at 217F and off at 208F, unless the AC is on. When the AC is on, the high pressure cutoff along with coolant temp controls fan operation.