cooling fan wil not activate........checked fan.......ok...........replaced relay under headlight.....what next?????

Are you sure it's not comming on because it's not warmed up enough?

It sounds silly but it may be just that.

Also your jeep uses a sensor to tell the fan to start you could replace that if everything else fails.

Another but not likely problem is a nonopening thermastat if no hot water is moving to the sensor then it does not tell the fan to start.

If your reading a high coolent level in the Jeep with thr factory guage it may be wrong.

Try turning on your AC I think that should make the fan turn on, try to see if you can hear the fan relay kick on for the fan.

Best of luck, if you find out the problem let us know.

Are you sure it's not comming on because it's not warmed up enough?

It sounds silly but it may be just that.

Also your jeep uses a sensor to tell the fan to start you could replace that if everything else fails.

Another but not likely problem is a nonopening thermastat if no hot water is moving to the sensor then it does not tell the fan to start.

If your reading a high coolent level in the Jeep with thr factory guage it may be wrong.

Try turning on your AC I think that should make the fan turn on, try to see if you can hear the fan relay kick on for the fan.

Best of luck, if you find out the problem let us know.


Checked everything.......even turned on the A/C still nothing....

Ok, this is a good one,

The only thing I can think of now is to take out the temp/sending unit and replace it, or take out the sending unit it's self and with the car turn on but not started put it into boiling water and see if you can get it to work, sounds crappy however if it was simple i'm sure it would be fixed by now.

I'm not sure but your 99WJ should have the same workings as my 02, and without looking right now I think the sensor is in the upper rad hose, you should be able to get it out, and it just may be to easy to replace it and try.

Can you check to see if it's getting power to the sensor? If anyone here knows how to manualy trip the fan sensor with a power lead please write in. If it was a Cyberdyne sensor I could help, but I'm kinda out of answers.

If you fix this I would love to know what caused it.
Good luck

I forgot to ask this, if you trip the relay on the fan does the fan start? you may want to find out why your getting no power to that wire "if your not".

My 99 JGC scared me the other day. While I was driving it was fine but when I got caught in traffice the temperature gauge went to 220 and was pushing towards the red. I turned off the air and it started to go down but in the meantime the oil gauge started creeping past 40. Once I was in moving traffice the temp went to 210 and stayed there but the oil gauge stayed at about 50. After checking all the posts I'm wondering if I need to have it serviced? I'm new to the FORUM and would appreciate any advice. Maybe I'm being a chicken after reading so many horror stories but I'd rather be safe than sorry. This is my second Jeep which my husband told me not to buy but hey, it's a Jeep thing. Please help.

I have seen alot of 99 Jeep problems, it's allways the first fun of a new car/truck that has the most problems, you may even notice some humming or a type or lound sounding vibe comming from the rear during hot highway traveing. (bearings in the D44, clearances were not set correctly in the rear at the factory)

You problem could be a number of things, like a bad connection at thr Battery, to a bad sensor a therma stat, the best thing to do is have the jeep look at by a place like Midias, no I don't work for one, but sometimes being Female dosnt get you correct prices at the shop, but even my better half didnt get the "Low Tail light fluid" song and dance at Midias.

(It's 2am not sure if i'm spelling Midias correct so sorry)

I bought my mother a 93 Jeep Grand, she lives out of state and was going to come down for a visit, she needed front rotors, and Pep Boys told her $45 each not installed

I went to the Pep Boys when she got down here and bought the One years for $20 each and put them on myself. They never told her about the one year warrenty ones, she didnt know they even have one year or life times, however they were trying to sell here life time rotors.

I do hope that you find the problem, if you wish for more input from everyone here click on "NEW THREAD" and use the subject line to ask for help or a question, you will find "NEW THREAD" in the area with only questions listed.

If you have any other questions you want to ask here I will get an Email that you posted, but unless sombody looks in here they will think it's for the orignal question that started the link, and since I was the last to answer I got a email saying sombody responded, just like the one you got in the mail since I posted. Thats why making a new Thread is the best way to get your questions looked at.

Good luck :)

I had similar problem and searching the forum I have concluded that it is the fan itself that needs replacing. I am able to start the fan up (when ac on or overtemp) by giving it a push with a stick, and then it starts, but it doesnt go at its regular high speed.
I have found some fans on ebay for around 100 and another place for 150 and will be buying in the next few days.

it just seems that the fan is to new to go bad, however if you replace it with another 99 fan would that not be changeing one bad fan from another?

If you figure this out please write in.

Its not a used fan part. Its a new fan assembly, though its not a Jeep manufactured, just an aftermarket fan, for a fraction of the cost.

I do hope that works for you, good luck