Wierd electrical fan prob. Help

[skog]

I have a 99 xj sport 4.0 w/ 110K. It over heats but only at idol. When I start moving it cools off to normal. I believe the electical fan to be the prob. When I runs a little hot, 220 ish the fan with run, when it climbs higher like 230+ the fan shuts off and then the temp just rockets up. I have had the jeep flushed and changed the fan relay. Is the fan bad, is it the temp sensor? any ideas?

thanks
skog

 

[Sig220]

If you are getting hot at idle, you will want to check the fan clutch. Not the electrical one, either

The mechanical fan draws air through the radiator which aids cooling, but with a bad clutch, it just spins and does not draw the air it should.

 

[skog]

I stuck a roll of newspaper into the clutch fan and it shreded it to pieces. I read on here that if the fan stops the clutch is bad. It has also been 100 degrees here and the jeep is black so I dont think the clutch fan is able to keep up with the cooling needs at stoplights. Am I testing the clutch fan wrong? Is that normal for the electrical fan ?

Thanks
skog

 

[lumberxj89]

The electric fan usually only comes on when the system starts to overheat - like when the car is idling. Next time it starts heating up, turn on the defroster, which will turn on the electric fan. If the coolant still heats up, you probably have a bad fan sensor.

 

[RBNRaider]

I would switch to a 160 degree thermostat and make sure you dont have any air in the cooling system.

 

[kennzz05]

on my 98 the fan seemed ok ran with the a/c etc. however after everything got nice and hot under the hood the fan wouldnt run or only ran at a very slow rate which i could stop with my hand as i had power at the plug when the fan wasnt working i replaced the fan with a cheepy i found on ebay for like 33 bucks so far so good bigest problem was mounting it i used two really large wire ties that are used for holding ductwork goodluck. check the plug for power when you feel that the fan should be running (above 220 or when a/c is on) if ya got power and no fan replace the fan. oh and i changed my fan clutch too thinking it was the prob

 

[Stone Dragon]

The electric fan usually only comes on when the system starts to overheat - like when the car is idling. Next time it starts heating up, turn on the defroster, which will turn on the electric fan. If the coolant still heats up, you probably have a bad fan sensor.

What he said!

 

[XJ4PLAY]

don't try the 160* thermostat. this won't help your issue.
I was told that there really is not test to determine a working clutch. just replace the at about 5 years.

 

[Starscream]

don't try the 160* thermostat. this won't help your issue.
I was told that there really is not test to determine a working clutch. just replace the at about 5 years.

X2 on the thermostat, but a pretty good test I've tried is this:

Let your car warm up to normal idle, around 195-210. Turn the car off and pop the hood. Right after it's turned off, try to spin the fan by hand. If it free spins, then the clutch isn't locking like it should. If it doesn't spin at all or very slightly does, then the clutch is still decent.

Mine recently died and this is the test I was told to try. AFAIK it's right. I'll be replacing mine soon and I expect it to fix my problem.

 

[MarkH]

I don't think anyone answered your question, so I'll try. If your fan goes on at all, then (obviously) the fan motor is not the problem and the relay (in the fuse box near the battery) is probably not the problem.

The electric fan works off of the CTS (coolant temp sensor) located in the front of the engine --screwed into the the thermostat boss with a 2-wire connector. Just follow the rubber hose from the radiator to the engine and you'll run into the boss.

That CTS sends a signal to (would you believe?) the ECM (car computer) which has a logic circuit that tells the fan when to turn on (with certain A/C settings regardless of temp and/or temp ~220F). That's a mere $25 fix.

It worked on my '98. Good luck.