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I'm back here again searching for some input on a non-running cooling fan. Some time ago I posted about the radiator fan not running while car was running.

I'll try to clarify what was happening and what attempts I made to fix it. For about 2 months now my car has been running abnormally hotter than normal. The needle climbs well above the M on the gauge after about 20 minutes running. I think I've got it narrowed down to the fact that my radiator fan isn't coming on at all while car runs hot... I mean the car can run 20-40 minutes the entire time and never once did the fan turn on. Yes, I've sat in the garage and watched it literally.

Now, if I unplug the coolant temp sensor, the fan kicks on, stays running - full blast. but the second I plug her back in, fan turns off and will not turn back on at all, even if you let the car stay running to a critical point to which I kill it and leave it alone (once the needle climbs past the 'M' on the gauge, I turn her off).

Here is what I've done: replaced the coolant temp sensor - no change. Replace the fan relay switch thingamabob - again no change. Okay, replace the entire unit behind the pasenger side headlight, again no improvement. My fan is not turning on unless I physically remove the coolant temp sensor.

Here's the upside on the rest of the cooling system should it need mentioned: Radiator a little over a year old, coolant just changed last October, thermostat changed along with coolant change. Water pump - well she's as old as the car, 165k miles - will be addressing that soon, but that has nothing to do with a non-running fan. The fan itself is the original but I am assuming if she run's when I unplug the CTS then the fan itself is not the culprit - or could I be wrong?

Right now I'm leaving her parked because she's running to hot, imho. I'd like to get her straight again as the weather is warming up and I prefer to be driving my cougar over the S-10.

Could there be anything I am overlooking involving the cooling that I am not thinking about?
 

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If you turn on the AC, does the fan come on? With the 2 speed fan, with the AC on and under most conditions, they fan should be on high speed. It sounds like there might be an issue with the wiring to the fan. I also don't know if maybe the high speed fan is what is working when the temp sender is unhooked or if it would do the low speed fan.

I can try to post up the wiring diagram for the connector and you can see if you are getting 12 v on the low side when it should if you haven't checked that yet.

Do you know anyone that can datalog your car, like with an XCAL2? You can watch to see if/when low and high speed fan is commanded.
 

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Discussion Starter #3
Datalog is what I am wanting done, unfortunately don't know anyone with a XCAL2.. The wiring diagram is what I've been spending last half hour trying to search on the internet as I am leaning towards thinking it's some issue with wiring related to the CTS? This is becoming a headache, almost - ALMOST tempted to just throw in the towel and haul her down to Ford and say, "find it, fix it." But then Ford will keep her for 4-6 days and give her back saying they couldn't find anything wrong - I don't like leaving my girl parked overnight someplace I am not, even if it is ford.
 

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The large connector on the fan shroud, Dark Blue is low speed, Brown with Orange stripe is high speed, and Black is ground.

Did you try with the AC on to see if the fan comes on?



I am guessing that the ECT is working right, but here is a chart for the OHM values, and if you want to test it hooked up the voltages expected.



 

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Discussion Starter #6
Thanks for that chart Bangster!! That is exactly what I've been banging my head over.
Alright, new update: This morning took the car and drove her around the neighborhood to get her warmed up, with the CTS plugged in. As the temperature climbed I turned AC on high, pulled over, lifted hood and monitored the fan. With the car running, AC - ON high I never saw the fan turn on once, Needle eeked past the 'M' on the gauge - disconnected the CTS, fan turns on (high) and watched the needle as the temp dropped to just below the 'N'. Drove her home.

**Do you know how hot the coolant actually is?
__________________
--Chris**

Chris, no I do not know the exact value of the temperature but I am wildly betting that at the 'M' the temp is probably around 220.
 

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Either you have a bad sensor that is shorting our or you have a short in the wiring to the sensor. You have two coolant sensors. One for the engine and one for the gauge. My guess is the one you unplugged was for the gauge and is the problem. I say replace the sensor. They are cheap!! :cool:
 

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I didn't get much time to play around with mine, and ambient temps are only in the mid 70s so I wasn't able to try long enough to get the fan to come on (I only got water temp up to 175 before I was called home to eat and other family functions).

AC on doesn't make the PCM command high speed fan, at least not from what data logging showed.

When I unplugged the drivers side ECT (the one used by the PCM, and gray) data logging it always showed 80 degrees and it didn't cause my cooling fan to come on.

When I unplugged the passenger side ECT (the one used by the cluster) I didn't see any differences other than the gauge didn't work.

I tried all PIDs I could when data logging, if I get a chance to play longer today I will see if I can get the PID for low fan commanded to see if it shows up, not that it helps you, but I am curious again.
 

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The reason I ask is because the gauge isn't the best indicator. Some are wildly inaccurate. But the fact that the low-speed fan doesn't come on when the A/C is turned on has me believing there is a problem with the low-speed circuit. Does your A/C in fact work when you turn it on? (i.e. is the compressor clutch engaged and spinning?)
 

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Discussion Starter #10
Either you have a bad sensor that is shorting our or you have a short in the wiring to the sensor. You have two coolant sensors. One for the engine and one for the gauge. My guess is the one you unplugged was for the gauge and is the problem. I say replace the sensor. They are cheap!! :cool:

No the one I unplugged was the CTS, if I unplugged the gauge then I wouldn't get a reading at all. I get a reading from cold all the way through the 'M' when the car is running. If I unplug the CTS while the car is running HOT I can literally watch the needle on the gauge drop from the 'M' to just below the 'N'. Now, when running the car with the CTS plugged in and AC on high, the fan doesn't come on. I've pulled over while the car was running hot, AC on high and checked for the fan to come on. No fan never came on while I physically checked to see if it would run or not. The car was running hotter with CTS plugged in and AC on, not until I unplugged the CTS did the fan switch on and the gauge visibly show 'cooler' temps.

When the AC is on, I do get cold air and all 4 speeds work. I tried checking the fan to come on thru different AC speeds but it never came on. I'm not talking about sitting and taking quick glances at the fan, I literally monitored the situation with the fan for maybe 10-12 minutes while the car was running - the entire time the temps climbed to critical and no fan came on. She is only coming on when CTS is unplugged. The much I am certain of. (sigh) kids fighting, I'll have to deal with this later.
 

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Discussion Starter #11
UPDATE - again.

Ok, this ongoing problem has now thrown me in a loop. Iwas once convinced the cooling fan was not turning on unless I physically unplugged the Coolant Temp. Sensor. So, anyway I had the car sitting in the garage while trying to figure out the wiring diagram for the CCRM to fan. The car was running the entire time and was frequently checking temps on the gauge to know how hot she was getting since AC was OFF and CTS was still plugged in. The needle was just ticking the 'M' on the gauge last I looked but thought I'll let her keep running a bit longer.
Ok, back to reading the schematics - when - fan suddenly switches on without me touching anything. CTS still plugged in and AC is still OFF. I'm dumbfounded. So I'm watching the temp gauge and literally see the needle drop from just above the 'M' all the way to the 'N'. The fan then turns off. The car is still running at this point so I let her keep going. Once again the temps rise clear over the 'M' and :eek: the fan once again switches on, temps drop and the procedure repeats itself over until I finally turned the car off.
The car must have been running for at least 45min. to an hour and never quit or stalled the entire time other than running hotter than normal.
So now I learned that the fan does indeed still function but is turning on much later. In the past, I've had the fan switch on when needle just hovers at the 'N'. So before anyone gets irritated with these constant questions and tell me to leave well enough alone, bear with me this once more: any input on this phenomenon or has this happened to anyone else? I guess one could say that I'm not comfortable with it running hotter than before.

**In my younger days when I just didn't care, I made the mistake of driving a 3.8 T-bird running overheated until it finally gave up the ghost - so now I get nervous when the I see the temps rise higher than I'm used too**
 

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UPDATE - again.

...
Ok, back to reading the schematics - when - fan suddenly switches on without me touching anything. CTS still plugged in and AC is still OFF. I'm dumbfounded. So I'm watching the temp gauge and literally see the needle drop from just above the 'M' all the way to the 'N'. The fan then turns off. The car is still running at this point so I let her keep going. Once again the temps rise clear over the 'M' and :eek: the fan once again switches on, temps drop and the procedure repeats itself over until I finally turned the car off....

Your fan motor has two speeds - low and high. One speed can be shorted while the other speed is not. To test go to AutoZone and borrow or have them run a high and low speed fan test with a scanner. If either speed does not work or your car misses or RPM's drop when you test your fan motor is bad. Otherwise as I guessed before you have a faulty CTS.

If interested there is a test you can perform with the motor with an OHM meter.
 

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I'm back here again searching for some input on a non-running cooling fan. Some time ago I posted about the radiator fan not running while car was running.

I'll try to clarify what was happening and what attempts I made to fix it. For about 2 months now my car has been running abnormally hotter than normal. The needle climbs well above the M on the gauge after about 20 minutes running. I think I've got it narrowed down to the fact that my radiator fan isn't coming on at all while car runs hot... I mean the car can run 20-40 minutes the entire time and never once did the fan turn on. Yes, I've sat in the garage and watched it literally.

Now, if I unplug the coolant temp sensor, the fan kicks on, stays running - full blast. but the second I plug her back in, fan turns off and will not turn back on at all, even if you let the car stay running to a critical point to which I kill it and leave it alone (once the needle climbs past the 'M' on the gauge, I turn her off).

Here is what I've done: replaced the coolant temp sensor - no change. Replace the fan relay switch thingamabob - again no change. Okay, replace the entire unit behind the pasenger side headlight, again no improvement. My fan is not turning on unless I physically remove the coolant temp sensor.

Here's the upside on the rest of the cooling system should it need mentioned: Radiator a little over a year old, coolant just changed last October, thermostat changed along with coolant change. Water pump - well she's as old as the car, 165k miles - will be addressing that soon, but that has nothing to do with a non-running fan. The fan itself is the original but I am assuming if she run's when I unplug the CTS then the fan itself is not the culprit - or could I be wrong?

Right now I'm leaving her parked because she's running to hot, imho. I'd like to get her straight again as the weather is warming up and I prefer to be driving my cougar over the S-10.

Could there be anything I am overlooking involving the cooling that I am not thinking about?
I had the exact same problem and finally gave up on it. What I have done for the time being is just wired a switch into the dash for the fan! Just be sure to keep an eye on your temp and also that you do not leave it on when you leave your car. If you find out what it is I would be very interested. I went through all that sensor junk and that relay box as well.
 
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