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Discussion Starter #1
I have a 1994 Thunderbird with a 4.6 and the electric cooling fan is NOT comming on when the engine is hot, the gauge went past the M in NORM and it STILL didn't come on.. if you put on the A/C it WORKS! I got this car with some issues like it having 13 year old coolant, 13 year old thermostat, no air dam undernear and the fan not comming on. I just flushed the coolant, new thermostat and installed an air dam. Since I've done all that it runs cool like it should at OP. TEMP. right on the N in NORM but once the car sits running the temp needle slowly goes to the middle.. lack of the fan helping it cool off the radiator.

So my question is:

Since the fan doesn't automatically come on when it reaches that magic temperature number BUT does come on when the A/C is put on.. where do I start looking to diagnose this?

Thanks!
 

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Do you let the needle go a little passed the middle? The fan has two speeds, so if the normal speed is not working, then the high speed side of the fan would come on at a higher temp.

When you turn the ac on, is the fan constantly coming on and off at idle?
 

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Discussion Starter #3
To me the needle should go to the N in NORM and not move unless its insane heavy traffic or something to that effect of having to sit a long time. The needle during the flush at only 1 point went pretty high (old thermostat was sticking) it was between the M in NORM and the evil H (Hot), I QUICKLY ran under the hood and the fan was OFF, I then quickly turned off the car(Don't worry it didnt over heat!). With the A/C on the fan turns on and stays on constanly like it should. Where can I begin to look to diagnose this? I'm figuring its just a stupid sensor or a switch, its always a little thing that causes a big problem. I'm figuring the ECT sends a signal to the PCM and then PCM tells the fan to turn on when its needed. I'm just not exactly sure where to begin testing at!
 

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hmm, don't be too afraid to let the car get to 3/4's of the way (I would shut it down). If the fan doesn't come on by then, then there's def. a problem, as you say, with the coolant sensor going to the PCM.

The needle on M sounds about the normal operating temp, whereas on N, that would be too cold for the engine.
 

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Discussion Starter #5
I always thought the N was the MN12s "spot" because my '91 Cougar always is at the N as is my dads '94 TBird also is always at the N. My buddies and teachers at school tell me as long as its in NORM is normal. Well atleast with this issue I can just use the A/C and have the fan on and it is the summer so, it's cool. So what do you think, maybe a wire got cut\unplugged\damaged that goes from the PCM to the fan where the panel(A/C) wire to the fan is good so it works? If the ECT was bad my temp. gauge would not function, correct me if I'm wrong.
 

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Run a positive and negative wire from your battery to the plug on the fan motor. It should come on. If it does check your fuses or your temp sensor. If not you need a new motor and no you don't have to replace the whole shroud. Just grind off the rivets and get some nuts and bolts.
 

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Discussion Starter #7
I think since the fan comes on when I put the A/C on that rules out a bad fan motor or a blown fuse.
 

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Discussion Starter #8
My teacher and I believe it is possibly a faulty IRCM\CCRM. This teacher is pretty cool and all for helping me out because he himself has a black 1997 TBird with a 4.6 and a 1995 TBird with a 4.6 and previously in his career worked at Ford\Mercury\Lincoln dealerships.
 

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For what's it worth, my honda had identical problem. the fan would come on with a/c, but not at regular hot temps. So the culprit was one of the fan temp sensor relays.
 
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