Engine Cooling Fan not working (red engine temperature)

Hi,

New to the site and this probably has been covered before but here we go anyway.... Was driving the wifes C3 1.4 SXi ( 52 Plate, aircon but NOT climate control ) the other day and got stuck in a little traffic. Didn't immediately notice but the engine temperature had risen to the red ( no beeping ), put the heaters on, got into clear air ( within 5 minutes ) and it quickly dropped down from the red straight to the 3rd bar. Hadn't had time until today to look into this and after a 10 mile run, left the car idling to see if the fan cut in. Well the temp guage went straight from 3 bars , up to the red ( again no beeping ) , but the fan also didn't cut in. My question is where do I go from here, as from a little research I see the fan is controlled by the ECU, but I also wonder is it getting up to fan temperature, seeing as its jumping from 3 lights skipping very quickly through the 4th yellow, the orange and then onto the red light within a second! Is this the fan, or is it the temp sender...which wires would i need to poke with a multimeter to check volatge ( on the fan )when the engine is warm??

Cheers in advance for the help

Kieron

Hello ronniecabers

If you can find the plugs on the fan unit itself, you can check there.

2 plugs, one with 2 wires and one with 3 wires should attach to the fan unit. These bring power and the control signal from the engine ECU that you mentioned. The 2 wire plug has 12v and earth for fan power, the 3 pin plug has the control signals

As for temperature sensors, you should have two! One for the in car temperature gauge and the other provides data to the engine ECU, among other things, to engage the cooling fan.

This may explain why the in car displayed hot, but the fan didn't run. Either sensor being faulty can give the same symptoms


Other strange temperature faults may indicate a faulty thermostat.

The C3 cooling system uses this special coolant.

The 2 fan connectors seen on some Citroen C3 models with variable speed fans.

Hi
Thanks for the reply.

If i disconnect both plugs for the fan, can I check if the fan actually works by connecting a 12v feed and an earth, i take it i would need a power signal down the ECU (, can I replicatethat in any way? )

Also regarding the temp sensors, is there any way of testing ( the resistance possibly ) to tell if one is faulty?

Cheers
Kieron

There are 3 coolant temperature sensors listed for the 1.4i C3 2002, there is the Green 2 wire temperature sensor,

the Blue 3 wire temperature sensor

and the Green 2 wire 25.5mm temperature

The 2 wire ones look like standard thermistor, but I don't know how the 3 wire one works . You can measure the resistance of the sensor at different engine temperatures to see if the resistance is ok, but without knowing what is to be expected how do you know what's right and what's wrong. Just changing them is a quick way to prove or disprove them.

2 wire sensor:

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click here for the sensor on ECP


Sometimes its a problem with the connector or wiring, so its worth removing the plug and spraying the plug and socket with some contact cleaner before getting too stuck into testing and changing stuff that is not really faulty. There are other problems with the C3 that turn out to be a bad connection on the plug and socket, so don't get caught out by a poor connection at the plug.

I don't know how to 'fake' the signal from the engine ecu to fool the fan unit. A simple check would be to check there is 12v and an earth for the fan at least when it should be running. That takes care of the power side and you may not even need to get stuck into the control side.

Hi

Thanks for the reply.

I have checked the 2 wire feed to the fan and that does have 12v, the only problem now is how do i actually tell if a/ a feed is being sent to the fan, and b/ if the fan motor even works?

Cheers
Kieron

Hi Kieron

I did a few tests on the control signal for the fan unit on a Diesel C3. lexia (available here) gave me the option to test the fan which powers up the fan then changes the control signal to slow the fan speed down until it stops. (There is a topic here that has information about using lexia that is well worth a read) then reports that the fan worked as expected.

During the test I managed to stick some meter probes into the control wires on the plug on the fan. The wire colours are going to be different to the petrol version, but hopefully the control system will be similar.

The diesel has a 3 pin plug. One wire (white) always read 12v to battery earth (its fed from the BSI), Yellow didn't read anything (fed from the Engine ECU) and the pinky purple one (fed from the Engine ECU) measured 8v (to battery earth) which decreased as the fan slowed down. Its highly possible the pinky purple was more than 8v before I managed to look at the meter, so Its probably 12V for full fan speed.

My guess is the yellow is the 'low fan speed' option that the diagnostics offered, but didn't seem to respond, so I guess its not fitted to that particular model.

Hi ,

Just a quick update for those interested! Finally had time to look into whetehr I was getting power to the fan via the ecu. Left the car running to get hot, sat there waiting , hit the third bar, and I'm thinking its going to hit the red in a sec, but 10 mins later no moment to the red . Checked the engine bay and the blinking fans now working , and all i did was unplug the connections and plug it back in! Ilike cheap fixes

Cheers for all the guidance , but appears to have been a bad connection!

Cheers
Kieron

Hi All,

Sorry to drag this one up again , but the problem has reared its head again. The car is getting hot and appears no longer to just be a lose wire , unfortunatley! I have changed the 2 pin green plug sesnor on the thermostat housing, but the other plug , the blue one, is only 1 pin, whereas the only ones I can find online are all 3 pin plugs. I only have one wire going to this blue plugged sensor, and this wire connects into the same wires as the green plug ( so same point in ECU ) , so guessing this must be the source of the problem......BUT why can't Ifind this sensor anywhere online???

Cheers
Kieron

ronniecabers wrote:Hi All,
BUT why can't Ifind this sensor anywhere online???

What engine do you have (8v or 16v) petrol 1.4 or 1.1

You can add your car info to your posts automatically by following the link in my signature (below).

If its a UK registered car, you can PM me your registration number and VIN and I can look it up for you.