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2001 Jeep idle operating temp


NAXJA Forum User
Norfolk, VA
Hi guys-

You are all a great resource for someone like myself that loves their Jeep, but is not mechanically inclined.

Quick question - I think I am being paranoid, but now that summer is here, my temp rises at stop lights to slightly above 210. It goes down again once I am moving to the more normal area just under 210.

I presume this is normal, but am concerned as I had to replace the radiator and thermostat were changed six months ago. What I have is a 2001 Jeep Cherokee Sport.

Is there an auxiliary fan that should kick on to cool the engine while idling at stop lights?

Any advice would be greatly appreciated.

The aux fan [electric] comes on under two conditions, first one is you have either the AC or defroster selected at which point it comes on when the compressor cycles. The second one is they are triggered by the computer to kick on around 220 or so. I've never had mine come on and [knock on wood] have never had my 98 go over 210 so I don't know. Even on trails it never goes above 210 w/ac on.
What I would check is whether the serpentine belt is tight enough. One of my customers/friends and I got into a heated discussion over this. He said his 'feel it, twist it, push it' method is close enough. I pulled out my krikitII tension gauge and slapped it on a 95XJ he had just replaced a water pump and rad in [good coincidence eh :D ] and the belt tension that used his method put the belt at under 100lbs when it should have been 180lbs being a new belt. Now he has some fancy tension gauge from snap-on or mac that he uses... The krikitII is available from napa for $14 or so.

Classicly though, the idle overheat and clear road cooldown is caused by a bad fan clutch on the mechanical fan. Dealer item or car quest but you have to be careful not to get one too thick or it will get the fan too close to the radiator if you manage to get it installed. CarQuest makes one the correct size that is considerably less expensive than the OME dealer one.

Somebody needs to post that carquest/ac delco part number next time they buy one of the correct size. I figure I'm getting due at 266,000mi and I'd just like to order one and put it on the shelf against future use.. I just did my waterpump, tstat, rad, hoses.
I have a 99 sport that acts the same way. Sitting at a light one day in traffic on my way to work, a/c off, windows down, and i happened to notice it idleing funny.....slightly high (say 800-900 ish) and the temp. guage had creeped up slightly past the 210. But the electric fan didn't come on....which surprised me, b/c if I go somewhere, shut it off, then start it up again shortly after, the needle will hit that same spot, and the fan will come on. So to cure this problem, if i'm sitting in traffic like that and it starts creeping up again, I cut the a/c on long enough to hear the fan kick in, then cut the a/c back off, and the fan will stay running untill it cools off enough. You might try that as a temp. solution on yours.

As long as it only goes a little over 210 I wouldn't worry about it. If it gets to where it really heats up when you're stopped in traffic, but then cools down when you get moving, that's the classic symptom of a bad fan clutch.
You could also wire up an aux. fan override switch if you're worried about it. If you do a search you'll find both places to buy a plugin setup and the 'how-to' if you're comfortable with wiring.
My '01 same same. Cruising is slightly under 210, traffic stop-n-go is slightly
above 210. I think there is a factory / dealer firmware upgrade to tell the computer to cut the electric fan on sooner than it came originally. My electric fan comes on at about 215.
Reviving a dead and old thread here - but I have a 2000 Jeep XJ that I am concerned about the temp rising when I am idling with the A/C on. For reference, I recently replaced the radiator with a single core unit, flushed the system and filled with 50/50 distilled water and Zerex G-05 coolant (my little coolant tester reads freezing point is -34* degrees) which is the suggested mixture of 50/50. Additionally, I checked my refrigerant level and all is normal (in case someone thought my refrigerant was too low).

I have noticed a few times that in city driving on hot days (+80 degrees) while stopped at a light the temp gauge starts to creep up past 210 (where it normally hovers) and tick closer to the next marker (around 222 degrees). My electric auxiliary fan did not kick on in any of these cases. When it did this, the engine started to idle higher (around 800-900rpms), and I could tell it was working harder.

I plan to check the aux fan tonight by pulling the coolant sensor plug and seeing if the fan kicks on. If it does, then I am trying to decide if the coolant temp didn't quite get high enough to trigger the aux fan relay/the ac pressure didn't build enough to trigger the aux fan relay, or if something is wrong. Perhaps I need a new fan relay (or aux fan, I will check that tonight).

Is this behavior normal for a 2000-2001 XJ?

From my research, Jeep changed the cooling system setup slightly for the 2000 and 2001 XJs from prior years. Instead of turning on the aux fan when the AC or defroster was on like in prior years, 2000 and 2001 XJs are triggered only by coolant temps hitting 218* or AC pressure rising above 1600 ksi. It seems like the 2000 and 2001 setup is not quite as efficient at keeping the system cool as the set up was for '99 models and older.

Based on this, I think something is not right with my cooling system. Thoughts?
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Temperature creep at idle, or on the 4x4 trails, is most commonly associated with a weak mechanical fan clutch. A single core radiator is not helping the issue.

I suggest some preventative maintenance by installing a new fan clutch.
Temperature creep at idle, or on the 4x4 trails, is most commonly associated with a weak mechanical fan clutch. A single core radiator is not helping the issue.

I suggest some preventative maintenance by installing a new fan clutch.

Thanks I was considering that. However, tonight I pulled the coolant temp sensor plug on the thermo after running the AC until the temp was creeping up again to about 222* and electrical aux fan did not kick on. The temp gauge dropped and the CEL came on (as expected) but the fan did nothing. I believe that means the aux fan is dead or there is a short somewhere. Considering this is the original aux fan, I am going to swap in a new one and see if that fixes the issue.
The e-fan should have turned on. Apply 12 volts directly to the e-fan to test.

Thanks I plan to do that tonight. If that doesn't work, then I have a replacement Dorman e-fan ready to go. If that doesn't work, then I will try replacing the relay. Hopefully one of the above should work...
I fixed my issue. I hope someone else finds this some day and it helps them - i can't stand it when someone posts about an issue and doesnt say what resolved it.

So I replaced my auxiliary fan with a dorman unit, but still it was not kicking on. I then replaced the under hood relay, still no joy. The aux fan would not kick on once temps started to rise as it is supposed to. Took a look at the "Power Distribution Center" under the hood, which is the under hood fuse box. I found that the "Radiator Fan Relay" as Haynes calls it was fine. However, the 40amp fuse next to it labeled "Junction Block" was burnt out. Swapped in a new fuse, now the aux fan is working! Kicks on just as it should when the temp rises to 217* degrees.

Hopefully the below diagram helps other 2000 and 2001 XJ owners (I believe pre-2000 the PCM or under hood fuse box was a slightly different layout).