Where or what sends the signal ??? located??
The fan runs and will cool ,, but only when the temp guage goes over the half way mark .
At this temp the jeep is starting to experenceing over heating problems.
Unless they have there fluid leaks out from seal failure or the bearing in them goes bad and it woobles around, they do not "wear out" as there is not else to wear out in them. What does happen to them is that the bimetal coil on the front of them ages and when it does it raise the engagement temp and the clutch is considered worn out then by many. Actually the coil is adjustable and if it has aged to the point that it does not engage properly you can tweak it back into running order. I have been doing this for over 25 years now and I have only actualy replaced one clutch because of bearing/seal failure during this time and it was about 20 years old too. Below is a link on how to adjust them if you are interested.
This is an oil driven fan, on a PWM circuit, commanded by the PCM.
If the engine is overheating, the first thing you should do/have done is a block check for combustion gases. I've done head gaskets on a couple of these for this concern.
Good luck.
WJ's w/4.7 V8's and WK 5.7 and Diesel use a Radiator Mounted Hydraulic Powered Fan.
The Power Steering Pump has two rotors and two circuits, one dedicated for the Fan and one for Power Steering.
The Hydraulic Fan is driven by a Gerotor type motor and there is a solenoid on it which shifts displacement, effectively changing the speed from a low range to a high range. Even with this arrangement, Fan Speed is proportional to Engine Speed because of pump in the PS runs according to the accessory drive belt ratio.
The Fan is controlled by the Engine Controller and responds to Coolant Temperature and AC Head Pressure to turn on or change ranges.
My '01 4.7 WJ consistently ran coolant temperatures indicated at the halfway mark on the gauge. No problems ever, tremendous amounts of airflow from the fan. The biggest problem I had was groaning in the high pressure oil lines after the isolators got old and hard.
Blockage of course (bugs, debris, cottonwood fuzz etc.) will reduce airflow a lot, even with a powerful fan leading to overheating.
4.7's also have an inlet side T'Stat and '00's and '01's had some problems with the coolant chamber mixing hot and cold and the correct function of the T'Stat.The 4.7 also has a coolant bleed screw on the top of the T'Stat housing because it is higher than the radiator fill neck and will trap air. Remember to bleed out the air after changing coolant or if you've let the CRS bottle run low and it aspirates air into the system.
reboot
pulse width modulated
'Tis a way of controling speed using essentially a square wave signal with varying on-times.
-- Old Crow "Yol Bolson!" '82 FLTC-P "Miss Pearl" '95 YJ Rio Grande BS#133, SENS, TOMKAT, MAMBM
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