thanks for your reply freegdr,

ive put in a new coolant temperature sensor aswell yesterday since the waterpump and thermostat got too hot i figured the sensor might be broke too but we didnt take it for a drive yet.

now the clutch you mentioned this is for the mechenical fan not the auxiliary fan right ? i spun the mechanical fan by hand with the engine off it just spins less than half a turn im not sure if that means the clutch is bad or that you mean another clutch ?

thanks marc

 

If the clutch on the mechanical fan wears out gradually which MOST do the symptoms also come on gradually. There is no sure fire test for good or bad because it can be in between those stages. General rule of thumb is if you don't know the history of it (it's age) replace it.

 

My AC has never worked. My e-fan works fine.

 

Unless you know when it was last replaced Id replace it. And yes mech fan. Get jeep to 210 shut it off then spin it.

 

Very well will if system operates properly. If Fan comes on and off when ac is switched on and ac clutch does not engage you have another issue .

 

ah i havent tried that yet freegdr i will and see how it reacts then

ive worked on jeeps before but these issues are new to me its interesting and i learn a lot
thank you

 

ok an update..

ive had the engine run for about 20 mins the temperature went up and over 220F the auxiliary fan did not turn on at all (only when unplugging the cts manually)

the mechanical fan i spun that while engine is cold and stops immideately just barely turns on its own after a push. after having the engine run for 20mins the mechanical fan reacts exactly the same try and spin it it barely turns by itself after a push.

turn on the a/c while the engine is up at 220F the auxiliary fan does not turn on the air from the vents does feel like its air conditioned too cold for just circulating air.

what ive done so far is:

new coolant full strenght 50% and 50% distiled water
new thermostat 180F
new waterpump
new coolant temperature sensor
new fuse 20amps in the pdc on position 15
relays A and B in the pdc are tested and working order
radiator is nice and hot all over and is not glogged

im about to go to the store at get a mechanial fan clutch cause what ive been reading the fan should not be this rough to push when engine is cold. i do realize that a new mechanical fan clutch does not solve auxiliary fan problem but the engine should not get this hot by just sitting idle reaching over 220F

any suggestions appreciated thanks

were planning a roadtrip in the next coming week so i have still a few more days to get this in order,
hehe trying everything seems like

 

ive passed on the fan clutch the new one feels just the same as the old one so i didnt buy it, after talking to the guy at the autopart store going over all these issue he recommended to rent the headgasket tool tester that sits in the radiator, the tester is 30$ for rent and return in 48 hours the liquid i needed was 10$ for a bottle. my oil is clear and the antifreeze is not discolored still he said it could be the headgasket leaking exhaust into the coolant.

sighs.. gonna give this a try

 

If head gasket was bad coolant would be pushing back out thru coolant bottle. Does ac compressor clutch kick in when turned on ? If not fan will not operate...You stated...ive had the engine run for about 20 mins the temperature went up and over 220F the auxiliary fan did not turn on at all (only when unplugging the cts manually)..This tells you fan and circuit are good. Sounds like either bad sensor or its plug. When was last time radiator cap was tested or replaced.

 

i cant say or simply dont know how to know if the air conditioner clutch kicks in, is there a way to test this in some way ?

when i unplug the coolant temperature sensor the Check Engine light comes on (seems to me the wiring is ok then) and the auxiliary fan starts to spin and this is a brandnew sensor and this was exactly the same with the old sensor i just got this sensor to eliminate this but apparently this doesnt seem to be the issue.. i cant imagine 2 broke coolant temperatur sensors?

about the radiator cap.. i couldnt say all i know is its not leaking or anything i can feel pressure at the top radiator hose while the engine is running at operating temperature.

 

engine block/headgasket test concludes negative

im happy about that

 

im a bit of a loss here just dont know what to look for anymore :\

i believe ive checked everything that should involve the auxiliary fan but it just wont turn on.

have i missed something ?

at this point im thinking of installing a wire kit for the auxiliary fan with its own temperature sensor (maybe adjustable one) and straight to the battery.. but truely this is the last thing i want to do i like to keep the original setup there is just a fault somewhere i cant figure out im not even worried about the a/c at this point just want the cooling system to stay where it should be.

 

well after searching around on the forums i ran into this tread..

https://www.cherokeeforum.com/how-to...ace-pcm-399052

this would be the last spot to find the faulure of the fan not coming on. tonight or tomorrow i will remove the overflow tank that sits behind the battery to get to the pcm and have a better look at this. refresh all the connectors clean and perhaps open up the pcm to check for faults.. by just a quick look at this set up it seems like the overflow tank dumps its fluids right on top of the 3 connectors that plug into the pcm and perhaps thats where my issue is cause of my understanding the pcm is what actually engages the auxiliary fan to come on.

will let you know what happens after this

thanks marc

 

Deleted

 

Note from DJ
Just my thoughts on your problem for what it’s worth.
First of all I think that your concern over the fact that you are unable to get your Electric Fan to come on when you select the AC mode is never going to happen.

Here is my reason why; when you select the AC mode the AC Clutch Relay located in the PDC is supposed to close and engage the AC Compressor clutch; which cause the AC Compressor to start the cooling process and energize the Electric Fan at the same time to aide in the condensing of the refrigerant. But there is a low pressure switch in this circuit that is probably not closed because the system is too low on refrigerant therefor it is saying no can do. That’s why the Electric Fan is not coming on in the AC mode.

Now on to the real your problem at the moment is your concern over the fact the Electric Fan is not coming on at higher temperature readings of the DASH TEMPERATURE GAGE. The fact the Electric Fan doesn’t work in AC mode has no effect over this problem.

So on to my thoughts on this concern.

On Jeeps there are two coolant sensors. There is one at the front of the engine in the thermostat housing, this one has two wires. The two wire sensor located in the thermostat housing sends its signal to the PCM for performance issues.

Then there is another at the back drivers topside of the engine cylinder head just to the right of the valve cover, this one has one wire. THE ONE WIRE SENSOR IN THE BACK SENDS TEMP READINGS TO THE GAUGE IN THE JEEPS DASH. If you temp gauge isn't acting right, this may be where your problem is and may need replacement. These too different sensors work independent of each other.

So the Dash Gage may be showing a much higher false temperature reading then the front sensor is seeing; which is the sensor that if needed will send out the signal we need extra coolant help and turn on the Electric Fan.
Photo of Dash Gage Sensor


Temp Sender Switch Temp Rating: At 100 Deg. F. 1320 Ohms With 2% Tol, At 220 Deg. F. 1250 Ohms With 2% Tol Edited by DJ on the 16th this value should have been 125 ohms not 1250 ohms
Temperature Switch Thread Size: 1/8 x 27 in.