Aux fan comes on late -searched-

[Onkover]

Yes I did search.

My Aux fan is not coming on by itself till the gauge reads almost red. The aux fan was upgraded to a 97. Almost always off road it's on. I do have it on a switch to turn it on from inside the cab. This was the kit that came with the proper wiring and the relay. The fan does kick on with the a/c. I don't use the a/c much but it does kick the fan on.

I have been having cooling issues for some time. In the effort to combat this I have installed almost everything new within the past few months. I have a Flowkooler water pump, new hoses all around, new heater control valve, new CSF 3core radiator, Rock-it thermostat housing, new 195* stat, new sensors for the gauge and in the t-stat housing (Done today), Zirgo 3300CFM main fan replacement, hood spacers, new splash guard and water wetter. I have gone through the entire system with a fine tooth comb. Why it still gets hot is now beyond me. Why the aux fan is not coming on till around 240* is also beyond me. I need some advice... it's getting real hot where I live. I don't want to mcook the fresh engine in her.

Specs.
92, 4.0 with about 5,000 miles, Auto
Full discription here

 

[Onkover]

Anyone? This one has me stumped.

 

[XJ Samo]

Did you look into the temp sender? Mine went out a last summer and just before it stopped working it turned on only when really hot. I'm not sure were it is on a 92 but mine (88) was left side of the rad. about half way down and is a brass fitting.
Sam

 

[Jess]

Did you look into the temp sender? Mine went out a last summer and just before it stopped working it turned on only when really hot. I'm not sure were it is on a 92 but mine (88) was left side of the rad. about half way down and is a brass fitting.
Sam

That is the temp sender for the fan. In a 92 it should be in the thermostat housing. The temp sender for the gague is in the rear of the head. Check it good with a temp gun and make sure the gague is reading correctly. If not replace the temp sender in the head. Alot of us have had problems with aftermarket senders, so going OE from the dealer would be the safest bet.

 

[Onkover]

I replaced that sensor yesterday without any change. The sensor was not listed under a 92 so I got the one for a 93. According to Jeep they didn't use that sensor till 93. My Jeep is a 92 1/2 but I have also seen them on 91s.

So yes, I have replaced that sensor. The gauge still reads just as it did.

 

[cygnus58]

this may sound off, but try getting ahold of one of those laser temp devices. I have read they can be had for around 20 bucks. point it at various points near the thermo housing. I don't know how many degrees less to consider, but metal sure is a good conductor of heat. IT should read very close to the coolant in there. This would say if your gauge system is off, or you really have a flow problem. If you were talking of the radiator sensor, (not sure which you have after reading the thread) try it there also.

 

[Onkover]

Yesterday I replaced the temp sensor in the thermo housing and the sending unit in the rear of the head. The laser gun is telling me that the gauge is correct. The numbers are vary close. Still the fan does not kick on till it gets almost to the red zone. When running off road I'll have both fans running and it still gets hot. Or climbing modest hills on pavement does the same also.

 

[Crawler]

Yes I did search.

My Aux fan is not coming on by itself till the gauge reads almost red. The aux fan was upgraded to a 97. Almost always off road it's on. I do have it on a switch to turn it on from inside the cab. This was the kit that came with the proper wiring and the relay. The fan does kick on with the a/c. I don't use the a/c much but it does kick the fan on.

I have been having cooling issues for some time. In the effort to combat this I have installed almost everything new within the past few months. I have a Flowkooler water pump, new hoses all around, new heater control valve, new CSF 3core radiator, Rock-it thermostat housing, new 195* stat, new sensors for the gauge and in the t-stat housing (Done today), Zirgo 3300CFM main fan replacement, hood spacers, new splash guard and water wetter. I have gone through the entire system with a fine tooth comb. Why it still gets hot is now beyond me. Why the aux fan is not coming on till around 240* is also beyond me. I need some advice... it's getting real hot where I live. I don't want to mcook the fresh engine in her.

Specs.
92, 4.0 with about 5,000 miles, Auto
Full discription here

Sounds like you've just about got it all covered. Take some temps with a good IRT and verify the guage is working. My fan ran most of the time as well when I was wheelin' it slow in the summer here in the desert southwest, but at the time my guage showed it going on at about 225* and off at about 205*. According to the IRT I used to verify this with, my guage was about 5* off to the hot side. Good luck.

 

[techno1154]

Yesterday I replaced the temp sensor in the thermo housing and the sending unit in the rear of the head. The laser gun is telling me that the gauge is correct. The numbers are vary close. Still the fan does not kick on till it gets almost to the red zone. When running off road I'll have both fans running and it still gets hot. Or climbing modest hills on pavement does the same also.

Try to do something to make the fan come on at a lower temperature. On my XJ, the ECM turns the fan on at about 230. 240* is too hot. Some on here say theirs come on at 220 or lower. I am not sure why this is so. Do an install of a different and independant temperature switch and relay(s) and or a manual toggle switch. There are several switch offerings on the market. You may find an adjustable one more to your liking. I am using one from the Renix era that is mounted in the radiator that turns on at 180* and off 10* lower.