I know the first thing to think about is that the fan switch is locked, but I tested 3 new fan switches, and all of them do the same.
The fan switch temp operating is 72-82. When the car reaches the temp, the fan starts, but when the temp goes down the fan don´t stop. testing the temp with a laser temp gun, it checks that the radiator is 55 degrees, but the fans dont stop. The next thing is the fuse, you may think it is locked, but it is not.
Checking the fuse, it works well.
If you disconnect the fan switch, the fan stops, if you disconnect the fuse, the fan stops, what means that the fan switch and fuse work well.
The car does not have thermostat, as I have fitted on top radiator hose a sensor to read the water temp.
The water hoses are new, the alloy radiator is new, the water tank and swirl pot are new. Everything is new.
Im really lost, Any one can help me with this problem???
THanks

 

must be the switches your trying are knackered!

ps why are you running WITHOUT a stat?

 

have you tested the fan relay??

 

yes, the relay is ok.
I wrote on the post fuse, but I meant relay. Sorry.
And the fan swith is ok, well I tested 3 fan switches and I dont think all of them are broken. I bough them new.
if they are broken, what can be the cause that causes that they are broke?

 

The mere FACT that the fan does NOT come on until it is UP to temperature, tells you it is NOT the fan switches sticking on.
Where are you measuring the HEAT at with your IR gun ?
The fans DO take a long time to go off once on if it is a very warm day, (not a problem in the uk!!).
Why not connect up a light so you know when the fans are actually on, the fan switches do go duff sometimes but very unlikely to be three in a row.
I think your heat gun(IR) is out also, so is misleading you, I bet if you leave it long enough it will turn the fans off.
tabetha

 

Hi Tabetha.
I have already a light fitted on the dash to see when the fan is on or off, even I have a switch to turn on and off manually the fan.
With the car stopped just idling, the fan starst when the temp goes up, but then it never stops.
I did a test yesterday and I waited about 20 minutes and the fan did not stop.
I changed the battery of the IR gun and I think it works well, as I aim to my hand and it shows 35 degrees.c . so it makes me think it works.
I take the temp very close of the fan swith, even on the own swith and while the fan is on, the temp goes down but the fan dont stop.
Now in Spain, summer is almost over, this week we are at 22 degrees and today we are 20 and it is raining. So it seems UK weather.
As you can se it is not easy to find a solution.
The radiator is new but, can it be operating bad?

 

are you using a genuine ford fan switch or a pattern one?
it sounds as though the switch is sticking open as soon as it gets to temperature & not shutting down again. what does the dash board temp guage read? does this go down when the fans come on?
other possibility is an airlock. try running the car with the header tank cap off for a while to get rid of any airlocks.
also what make is the rad? there have been a few cases of poor quallity rads not flowing properly

 

The fan swith is not genuine ford, the brand is FAE, but long ago I dont have a genuine fan swith.
When the fans are on, it seems that the original temp gauge dont move, the needle is always in the middle.
Tha radiator is an alloy one , is brand new a and is XS.
I have fitted a swirl pot.

 

try a genuine fan switch first from ford.
if not change the rad back to your standard one, xs power aren't the best

 

But ford have changed the shape of the fan swith conector and to fit it I have to cut the original one, and I dont like this idea.

Whe I unbolted the fan swicth, inmediatly came off a lot of water, so I assume that the water is in contact with the fan switch.

 

but xs power rads are crap & flow worse than standard
there may be water there but it doesn't mean it's flowing

 

Try disconnecting the overide switch and see what happens as it takes so little current to keep a coil winding(RELAY) energised, that the switch could easily be doing it, ie leaking enough current to keep contacts closed and fan on.
I would also first try another relay if the contacts(inside) are too close or the return spring is weak inside, the coil winding contacts have a NATURAL tendency to remain closed, called unintentional latching, very common on some relays.
tabetha

 

Sorry Tabetha but I dont understand what you mean on the above paragraph

 

I must explain one thing I have just rememberd.
two months ago both alternator belts broke ( they were bad quality ) and of course the water pump stoped and the temp went high.
I stoped the car inmediately and open the water tank cap to let the pressure go out. The water temp came down but I dont Know if that caused any problem related with the one I have now

 

I doubt that it did any damage if it happened two months ago.
Whenever a relay is energised, ie contacts are closed there is a degree however minute of arcing occuring between the contacts, this causes a furry edge to be made on the contact, the trouble is they need a nice clean surface for make/break operations.
To put it simpler they can get a bit dodgy over time, and some especially cheap ones can stick once energised(closed) they do not always open again to break the circuit, reffered to as latching.
It would be easy just to try another relay to elimnate this, doe not have to be a ford one so long as contacts are in the same position.
Some switches which again if not good quality can leak enough current through anti corrosion pastes used in them on the contacts to keep a winding energised in the relay.
Let it get to temp then pull out relay so fans stop then put back relay and see if they are still running, if now stopped you know it is a dodgy relay, unusual but certainly not unheard of.
tabetha

 

Thanks Tabetha. I will try and I will let you Know.
Do you think it can be the water tank cap??

 

Hi I still have the problem. I did what you told me, and when I put back the relay the fan keeps running.
I swap the relay and it did the same.
I dont know what to do.
The electrian says its a water circulating problem, and the mechanic says is an electrical problem. I´m in between and dont know what to do.

 

HI IAN I will undestand that if the temp went high and did not decrease, but the problem is that the temp decreases to much and the fan don´t stop.

 

dodgy wiring then. time to completely rewire your fans, think there is a tech article in here somewhere & in the last issue of fast ford

 

what a f.....n mess

 

Here I am again.
I swappped the fan switch. The one was fitted was 82-72 degrees, now I have fitted the original temp 88-77.
of course the temp goes higher, the fan stars and when the temp goes down it stops.
What it seems to me, is the first fan switch has a lower temp to stop the fan (72 degrees) and for any reason the water dont come so low.
The new one stops at 77 degrees, and seems that the water comes down more than that temp and stops, but the water is not able to go a lower temp.
Maybe the radiator I have (XS ALLOY ) dont do the job, or maybe I have a poor waterflow problem.
As I had a problem with the water pump belt, which I broke, and the temp went high for a very short time, I´m afraid of having a headgasket problem, but the fact is that the engine dont overheats.
I think maybe it can be the water tank cap.
I´m still lost

 

don't worry about it, cossies genrally run about the 80 degree mark. there is no way it will maintain 72 degrees esp when stationary.
my car has a new engine, new water pump, 60mm thick race spec rad & a pro alloy turbo cooler, my normall operating temp at cruise is 76-78 degrees thats in this country which is a little cooler than yours.
all sounds fine now

 

Thanks Ian.
Now I should fit the thermostat, but as I have a racetech water temp gauge with the sender fitted on the top hose, if I do it, the sender goes crazy.