AU Fairmont cooling fan issue

[Alan L]

Hi all,
My first post so hello to all and thank you in anticipation of help.
I have a high mileage 98 Fairmont wagon which is in excellent condition and is valuable to me way above what it’s monetary value is.
I note the cooling fans aren’t working. I have tried to research it on the net.
The fans themselves are working perfectly when ‘hot wired’ and the relays are ok.
I therefore think that it must be the thermistor switch in the cooling system that must be faulty.
The problem is I can’t find it on the head or thermostat housing where I would expect it.
Can anyone tell me where it is located and any special techniques to remove it?
Any help or advice is gratefully accepted.
Alan

[mad2]

Originally Posted by Alan L

Hi all,
My first post so hello to all and thank you in anticipation of help.
I have a high mileage 98 Fairmont wagon which is in excellent condition and is valuable to me way above what it’s monetary value is.
I note the cooling fans aren’t working. I have tried to research it on the net.
The fans themselves are working perfectly when ‘hot wired’ and the relays are ok.
I therefore think that it must be the thermistor switch in the cooling system that must be faulty.
The problem is I can’t find it on the head or thermostat housing where I would expect it.
Can anyone tell me where it is located and any special techniques to remove it?
Any help or advice is gratefully accepted.
Alan

there is a sensor at the back of the head [not on the side] .... don't remember what it's used for tho. and no idea on removal.

[Alan L]

Yes, I can see it there now you mention it. It doesn’t look very easy to remove.
The temperature gauge is working fine, I don’t know if that sensor is for the temp gauge. Either way, I suspect the fan switch must be seperate to the gauge sensor.
I’m really wracking my brains. I wouldn’t think it would be so hard to find.
Alan

[MuzzMelbourne]

Have you checked the fuses under the bonnet? There are 3 heavy duty suckers from memory. The little clear view caps come off and they cack themselves.

[AMB]

Originally Posted by Alan L

....
I note the cooling fans aren’t working. I have tried to research it on the net.
....

How do you know they aren't working?
They wont come on until the engine gets quite hot. Turning the aircon on, should make the fans come on.

[arm79]

The fans themselves, or the relays specifically, are triggered by the ECU. There isn't any other external fan switch or fan controller module.

The temp sensor in the back of the head is the only temp sensor. It provdes the temp to the ECU and the ECU shares the information with the cluster via a data link and the ECU uses that data to control the fans directly.

If the temp gauge is working fine then the temp sensor and any data it provides is working properly. So it would be something related to the whether the ECU is triggering the relays or a problem with the relays or their power itself.

As AMB said, the fans don't come on unless the aircon is on. So if the aircon is switch off or not working then they wont come on until the engine gets hot. In a BA/BF they don't come on until the engine gets to about 95 deg. Can't remember what it is for previous models.

It could be a problem with the ECU, the internal drivers are faulty. It could be a problem with the wiring between the ECU and the relays, which would be strange because there are 2 wires, would be strange both of them are faulty. Unless you have an active hungry rodent. Or it could be a problem with the +ve side of the relay, that there isn't any power going to it. Check all the fuses for a start.

[MuzzMelbourne]

Originally Posted by AMB

How do you know they aren't working?
They wont come on until the engine gets quite hot. Turning the aircon on, should make the fans come on.

True, I only hear mine on hot summer days, and then only in traffic.

Switching the a/c on should fire-up the right fan but its very low speed and very quiet. I had to get a torch to watch the fan blades to check it.

[Alan L]

Hi,
The car’s cooling system is definitely not ok. It usually runs at normal temperature (lower end of the normal arc on the gauge) but on a long steep grade the temperature rapidly increases. It quickly returns to normal on level ground.
I don’t believe the high speed fan is coming on when the motor gets hot.
The engine appears healthy with no coolant loss etc.
I have tested the fans and they both run when jumping across the relays.
The low speed fan works when the air conditioner is selected on.
The fuses are ok
Tomorrow I will swap all the associated relays with known good ones. I will post the results.
If that does not fix the problem I will rewire both fans to run continuously when the ignition is on.
Although the car seems mechanically in excellent condition it has recently experienced a string of minor but exasperating problems including;
the failure of the driven gear of the speedo transducer causing gear box problems. It was a green driven gear that was hard to locate.
Not long after the driving gear inside the gearbox extension failed, now fixed.
Failure of the oil pressure sender, now replaced.
Failure of the crankshaft harmonic balancer that also destroyed the crankshaft position sensor.
Failure of the air temperature blend motor. It was very difficult to find a replacement and very difficult to replace (I paid to have a Ford workshop change that one)
Usual disc and pad replacements
In spite of all this I really like the vehicle and believe if I get it sorted it will provide many km of comfortable economic country motoring.
Thank you to all for your assistance
Alan

[MuzzMelbourne]

Originally Posted by Alan L

Hi,
The car’s cooling system is definitely not ok. It usually runs at normal temperature (lower end of the normal arc on the gauge)

I have, finally, just sorted my cooling system out. What I learned was that normal temp on the gauge is bang in between the 'n' and the 'o' of the word 'normal' on the gauge.

Mine was all over the place depending on ambient temp and load, not good.

I did a Prenrite radiator flush, replaced the coolant with Penrite 500,000k concentrate at 33% dilution, both radiator hoses including new hose clamps, thermostat and expansion tank cap. Replaced both fan relays with new/secondhand non-coroded ones.

Now it gets to running temp in good time and sits there. If it moves ever so slightly to the hotter end, the main thermos kick in and a minute later its bang on again.

So, after years of worry I am now confident in my car's cooling system, a/c on or not.

[mad2]

Originally Posted by Alan L

Hi,
The car’s cooling system is definitely not ok. It usually runs at normal temperature (lower end of the normal arc on the gauge) but on a long steep grade the temperature rapidly increases. It quickly returns to normal on level ground.
I don’t believe the high speed fan is coming on when the motor gets hot.
The engine appears healthy with no coolant loss etc.
I have tested the fans and they both run when jumping across the relays.
The low speed fan works when the air conditioner is selected on.
The fuses are ok
Tomorrow I will swap all the associated relays with known good ones. I will post the results.
If that does not fix the problem I will rewire both fans to run continuously when the ignition is on.
Although the car seems mechanically in excellent condition it has recently experienced a string of minor but exasperating problems including;
the failure of the driven gear of the speedo transducer causing gear box problems. It was a green driven gear that was hard to locate.
Not long after the driving gear inside the gearbox extension failed, now fixed.
Failure of the oil pressure sender, now replaced.
Failure of the crankshaft harmonic balancer that also destroyed the crankshaft position sensor.
Failure of the air temperature blend motor. It was very difficult to find a replacement and very difficult to replace (I paid to have a Ford workshop change that one)
Usual disc and pad replacements
In spite of all this I really like the vehicle and believe if I get it sorted it will provide many km of comfortable economic country motoring.
Thank you to all for your assistance
Alan

underlined =
so low works with aircon on but no high? & no low or high when normally driven?.
how did you test the fuses?. don't go by visuals.
the green cog 'should' be fitted to all with the 3.23:1 ratio diff.

[arm79]

The fans dont run while the car is in motion above a certain speed. Mainly because its not necessary, the airflow from motion is normally enough, but it can be an impediment to cooling.

I wouldn't be wiring the fans to run continuously. They aren't designed to run continuously and it might cause issues with the engine temp control. Falcons typically run spot on around 93 to 95deg rain, hail or shine without any help. Interfering with that might cause you to use extra fuel.

Your problem sounds more like a blocked radiator, internally or externally, or maybe a slow thermostat. Making the car work hard when the fans are off and relying on airflow for cooling any blockage limits the cooling ability.

Temps that rise at low speeds and at idle are typically fans. Temps that rise when the car is moving, moving onto a freeway for instance, is usually a blockage in the radiator.

You recent lists of problems would be frustrating, specially if they happened in a short space. But they are part and parcel of owning an AU. I doubt there would be any AU owners who haven't experienced all of these in the course of ownership. Even back to EF/EL days. I had all those things happen in the ownership history of my EL's back in the day.

I'll admit the blend door is fun. Did a few of those in my time. Hopefully they didn't sting you too much as its not too had a job.

The difficult thing would be sourcing the parts given the age of the these cars now.

[Alan L]

Hi,
To answer a few very relevant questions posed.
# I tested the fuse with a multi meter.
#Yes, the temperature always ran between the N and the O on the gauge.
#The overheating problem came on very suddenly leading me to believe it is not a radiator core problem
#I’m quite sure the high fan is not coming on even when the gauge is reading quite high.
# The problems all started around the time the Speedo drive failed. Of course this caused all sorts of gearbox problems. I even noted the smell of overheated ATF. I will change the transmission fluid ASAP. Not sure if the failure of the cooling fan caused the high ATF temp or whether it was a result of the gearbox not operating correctly.
When both the driven gear and the internal driving gear failed I was hundreds of km from home, ironically both times with the Snowy Mountains to cross.
# I have not checked the thermostat or the water pump. I guess I should include them on my list as both could give symptoms similar to what I’m experiencing. Again to repeat myself, the temp only increases on long hard grades (I have not been in city traffic) and quickly returns to normal on the flat.
# I will hot wire fans just to confirm they are the problem
Again, I’m so appreciative of the help you are offering me. I will solve this and share my experience

[Uncle_Ken]

Thermostat maybe next, not to expensive to replace

[Alan L]

Thank you all for your help,
I have changed all the relays and now the fans are working.
I will keep a close eye on it and as they say in the army, hope for the best and expect the worst.
Regards
Alan

[Uncle_Ken]

That's something the Forum is for.
And Welcome to the AU forum