cooling fan 1997 smiley face

[Diddymus]

I wonder if anyone can suggest a solution to my issue. I have recently purchase a 1997 transit van campervan Devon discovery. I'm going through it slowly as there are a number of faults that i am rectifying. The most baffling one is the cooling fan doesn't appear to run when the engine gets hot. I think that a previous owner has taken the thermostat out as the engine runs cold and did so from picking it up and traveling over 80 miles, there was just a hint of warmth coming from the vent and as I say the engine didn't get much off the cold mark. When stationary for a good 10 mins it does start to warm up and the indicator starts to rise, if i leave it long enough it eventually overheats but I stop it shortly before any danger to the engine. If I turn the blower motor on it does seem to control the engine temp fairly well. So thats one of the reason I think the thermostat is either missing of faulty and also the engine radiator fan doesn't come on when reaching critical temp so that may be faulty .
I am struggling to get any info on this 2LTR DOHC engine and van so was wondering what tests I can do to rule out the fault on the various sensors/fan etc I could do.
Really would appreciate some guidance on this issue. I'm retire electrician and can use a multimeter and fairly competent diy mechanic.
Thanks
David

[MinorMatt]

doesn't the 2L petrol have an electric fan? Its been a while since I have looked at one

[Diddymus]

Yes it is an electric fan , am going to check if it works first by disconnecting it from the loom and apply power to the motor and then work back ,however I dont have any schematics for the electrical system that controls the fan motor, are there any relays that the temp sensor feeds into , I'm really stumpt without any info so its going to be a ling slog with out any input from people like you.

[dumper]

Not had a 2.0 L twin cam in a transit but I did have one in a Sierra xr 4x4 and had a problem with the fan not cutting in I think it had a thermostat switch on the radiator and it had dirty contacts think it had two pins so you link them together to test the fan motor.
But I’d definitely have the thermostat out to check it .
Mine did blow the head gasket I was plotting the route of a road rally with it ticking over and didn’t realise it was over heating till it was to late now Ford say that the head cannot be skimmed but it is possible a head specialist was able to do it probably nowadays you can get a thicker head gasket but I don’t know.

[MinorMatt]

Yes it is an electric fan , am going to check if it works first by disconnecting it from the loom and apply power to the motor and then work back ,however I dont have any schematics for the electrical system that controls the fan motor, are there any relays that the temp sensor feeds into , I'm really stumpt without any info so its going to be a ling slog with out any input from people like you.

There wern't *that* many 2.0DOHCs made. So most don't have them or have a lot of knowledge.

On the cooling circuit somewhere there will be a temperature switch - its most likely to be on/near the thermostat housing. That would be the first place I would look - remove the connector and bridge the wires in it (ign on) and see if the fan starts up. If it does, the switch has failed. Thats one of the more common, generic, reasons why fans don't work.

Any fuses and relays etc for the engine will likely be in an auxillary fuse box in the engine bay - it will be about 4" wide, 6" long and 4" deep with a flip up top. It would also be worth having a look at them.

I *probably* have the wiring diagram for the DOHC. Its not here so it may be a few days. I will see if I can dig it out.

You could always fit an aftermarket (in top hose) type thermostatic switch and disconnect the fan from the factory wiring entirely?

[Diddymus]

I'd like to thank you all for the advice and expertise you are sharing with me , I am just waiting for a nice sunny(ish) day then I will start to do some of the things you have suggested,

A wiring diagram would be great if you find one. Please keep your comments and advice coming in.

So far I have managed to find the fault on the intermittent wiper (on all the time when switched to intermittent on the stalk switch (was a bad relay module that I managed to buy for £20.00 , the heater motor only worked on full speed position 3 on the switch( found the resistor module £10.00 and replaced it ) job done.

If I bypass the wiring loom and fit a an after market thermostat switch will it affect the ecu ? Will this cold running affect the fuel measurement /delivery at the petrol injectors ?

The temp sender switch works and the gauge does work in the cab does this also send info to the ECU which then adjust the amount of fuel injected to cylinders ( ie cold engine then more fuel injected (richer mixture ?) Not quite sure if fuel injection works with similar principles to carburation)

I know I'm asking a lot of you all but I really need your collective help with this given I have no manuals etc ...sob sob sob lol
Thanks again
Didymus

[MinorMatt]

That depends if the fan is controlled by the ECU or not.

There is either:

1) a temp sensor, which sends the temperature to the ECU, which then sends a signal when to turn the fan on,
or
2) a simple thermostatic switch which bypasses the relay.

If its 2 - then there won't be any issues at all with aftermaket control
if its 1 - It depends whats failed. If the sensor (or wiring between it and the ECU) has failed, the ECU won't know what the temperature is and will likely be running rich the whole time. In which case you should replace/fix it. Any other failure mode, and aftermarket control will make no odds.

The temperature sensor for the gauge is a seperate part to the one for the ECU on most Fords

[Diddymus]

Does anyone know what this actually does, looking at the radiator front of my campervan this device is on the top right fixed in to the radiator cowling.
It is marked with 2.3 ohms and part number I think is
91AB9A 819AC
Or these are the numbers on the part, it connects in to the wiring loom at the cooling fan motor with the leads being red and black , the fan motor leads are green see pics.

20250224_150746.jpg

20250224_151331.jpg

20250227_103640.jpg

[MinorMatt]

Its obviously a resistor for a high load application. Entirely possible its fan related.

Have you got aircon? Almost every reference says scorpio or escort fan resistor for aircon?

[Diddymus]

There is no air conditioning in the van, looking at where it connect in the loom the black and red leads connect into the green leads feeding the cooling motor wires I think. Going to do some of the tests suggested in post and will check continuity of the wires connectors etc

20250227_103817.jpg

20250227_103640.jpg

[MinorMatt]

It may be used for a 2 speed cooling fan. The windings are certainly large enough to cope with the engine fan. A lot of electric fans have a resistor

You can always test if its the problem by bridging the 2 terminals with a suitably thick wire/piece of metal

[Diddymus]

Good afternoon , further developments to report. so near I discovered two sensors at the back of the thermostat housing, one controls the temp indicator ( i let the engine idle till the indicator started rising then disconnected it and the needle went back to below cold on the gauge) so I assumed the other sensor was the control for the cooling fan.
When I disconnected the other plug from the sensor, with in about 5 seconds the cooling fan started running ? I bridged the sensor plug with a wire expecting it to turn the cooling fan off but it didn't? but as soon as I reconnected the plug back to the sensor body the fan stopped, I repeated this procedure several times with the same result. Just wondering why when I bridged the connecter the fan would not stop or why when plugging the connecter back in it did stop the fan? I'm missing something here ? any ideas.
Thanks

[MinorMatt]

I've found a diagram...

[MinorMatt]

And the alternative one

[Diddymus]

Thanks for taking the time to upload the wiring diagram
I have ordered a new coolant temp/fan switch just hope it works, still wondering why when the engine runs and I disconnect the switch from the connector in the loom the the fan starts ( warming up) and when I plug it back in the the switch it stops. When I bridge the pins on the connector the fan continued to run but as soon as I removed the bridge and plugged the connector back in to the switch the fan stopped. When I run the engine up to temp and beyond the fan still doesn't start until I removed the connector from the switch ?? I'm guessing there is some sort of variable resistor or thermistor in this switch and not an open or closed switch?
Any Ideas pls would be helpful.
Anyway new switch ordered and I'll see if it works.
Thanks again
David