2004 1.6 Engine cooling fan not working

I did a bit of rummaging around and found this thread:
questions-about-a-petrol-powered-citroe ... -t400.html
Of interest is a post by C3Driver52 who probed the wires in the 3 pin connector.
He found the white wire had 12V (wire 3 on my diagram below). This would be the relay power and "fail safe". If power was removed from this the fan would come on. To test my theory, if you removed this connector the fan should come on?
"Yellow didn't read anything". This would be ground reference for the PWM (wire 4 on my diagram).
He said "the pinky purple one (fed from the Engine ECU) measured 8v (to battery earth) which decreased as the fan slowed down.". This wire is mauve and would be the PWM wire and is wire No5 on my diagram. If read on a DC meter the PWM RMS value would fall as the pulses diminished. My guess is they are 12V PWM pulses.
FYI: wire 1 is permanent battery ground. Wire 2 (I think) is permanent fused battery positive.

Thank you very much! what a detailed answer!

I'll try tomorrow to attach the oscilloscope to the pwm lines and see if I am able to discover the thing (I'm not very experienced with the oscilloscope). Today I had an appointment with my mechanic for another car and he also told me that usually the fan is the culprit so I'm confident that changing it will solve the problem. I found one in my local craiglists for 20€ which I think it can be worth to test and if doesn't work I'll buy the amazon one (now out of stock).

Again thank you very much Ozvtr for your help!

Hi there again!

Quite a bit time has passed and I still have issues with my fan I did some trial/error and have good and bad news:

- First thing I went with my old promax oscilloscope to the car and tried to find the PWM signal. I were not able to find anything in the three pin connector, but it was not the optimal conditions so I don't know that if it was my fault.

- I ordered a new fan from Amazon. It was a very good deal (100€) but it was out of stock. After almost one month I cancelled the order and ordered from autodoc at more or less the same price but worse conditions if I want return it.

- I tested the new fan and got exactly the same results as before. The fan works in the full speed test but not in the low speed test it wasn't. So the same as my old fan.

After this I found other similar thread here and checked for pin corrosion in the motor fusebox, ecu and inside fusebox but everything was clear. I also applied contact cleaner but it didn't solve the problem.

The only good thing is that after I read the other thread I tested the fan with a coolant temperature of 96ºC (I started the motor and leave it running for quite a bit) and the fan started in full speed. So I guess that I'm safe from overheating the motor.

I found this


youtube video in which they fix a c2 with the same fan as mine by upgrading/reprogramming the ECU with Lexia. He has different symptoms but I don't think that reprogramming the ECU is something very recommendable so I don't know if I should try it.

Any advise is very welcomed because I'm quite lost here.

Thank you!!!

I'm sorry but I don't see your issue.
If the fan starts up at about 96'C and cuts out at about 95'C then there doesn't seem to be a problem (with the engine cooling system).
Can you out line what your concern is? Are we now talking about the aircon not working properly?
You said that the aircon compressor kicks in. Is that right?
The engine ECU runs the fan proportional to the high pressure side of the aircon system. The higher the pressure the faster the fan runs. The pressure is proportional to the amount of "work" the system has to do, or is asked to do. If the compressor kicks in but the fan doesn't run and you don't get cool air, you are probably low on gas in the aircon system. There is enough gas that the engine ECU will engage the compressor clutch but not enough to cool the system and not enough for the "high side" of the system to engage the fan.
If this is the case then you will need to get the aircon inspected.

Thank you again Ozvtr for your reply!

Now my main concern is why the fan does not work on the lexia's "low speed fan" actuator test and if that can be affecting the A/C or be the reason for not working. Yesterday I also checked the gas pressure in the Schrader valves as you outlined previously and it seems that is not a low gas pressure problem. The compressor is also fine (checked by the car shop guy in the last maintenance).

Thank you!

In the YouTube video, above, he couldn't get the fan test to work and postulated that it might be because it's a variable speed fan. I agree but I will try to test it on my car tonight.
The test might not be valid, my car and the car in the video are 1.4L with Sagem ECU's. Yours is a 1.6L, probably with a Bosch ECU. So the results might not be the same.
Another thing is; that car's fan was not working AT ALL! The car was over heating. You have confirmed that your fan runs and your engine DOES NOT over heat. Is that right?

Does the aircon get cold at all? Even if the fan is not working correctly, if you drive the car over 50Kmh/30Mph the aircon should get cold as there is air flow over the condenser and the compressor is at speed. Can you try that for me?
Just because there is gas in the system doesn't mean there is enough to get the system cold.
If the system does get cold, it could be the pressure transducer in the high side of the aircon system. However if that wasn't working the compressor might not engage.

I am trying to eliminate the aircon from the equation. I will try the low speed fan test tonight with the LEXIA and see if it works. I will also see if there is a speed change with the green thermo sensor. Unfortunately my aircon is not working at the moment as I have only just repaired it and have only partially re-gassed it to see if it leaks. Also it's winter here and I don't need it.

My setup for the "injection" has the fan as a variable speed (chopper) type.
When I activate the actuator button, the fan starts off slow and speeds up to top speed. Your engine is a 1.6l but I'm sure the setup should be the same for any variable speed fan assembly.
There is only one option for the variable fan test, NOT high and low speed. Has your ECU been configured incorrectly? Are you game to reconfigure the fan? Go into injection, configuration, highlight the fan option, Validate, select variable speed (chopper), validate and save the settings (bottom left hand button). Good luck.

When my engine gets to 96'C the fan runs at about half speed. If I disconnect the green temp sender connector while the fan is running, within about 20 seconds the fan ramps up to full speed. I think when the aircon is on the fan will spin slowly then ramp up as the demand gets greater. Otherwise the fan test is the only time the fan seems to vary in speed.

Does your aircon get cold when you drive around?

Hi there again! Thank you for your effort Ozvtr

Fortunately the fan does work when motor hits 96ºC so there is no overheating problem so I'm back to square one where only the AC doesn't work (but doing some test today I had a misfire cylinder error code that seems to disappeared later, bad signal...).

Today I drove the car for some kilometers and the AC does not seem to work also if the car is in movement. If the car is stopped the air is very hot but in movement the air is more or less at the same temperature as the outside. I also checked the configuration of the ECU and the fan is set as variable speed (chopper) unit, so that is also ok. I will check the pressure of the AC system and report back.

My ECU is a bosh ME744, you are right, but lexia shows high speed fan and low speed fan options. But as you described, with high speed option the fan start in slow mode and the speed increases over time. Maybe is an error and should be only one test.

Thank you again!

krasny wrote: ↑Mon Aug 31, 2020 2:50 pm but doing some test today I had a misfire cylinder error code that seems to disappeared later, bad signal.

"Misfires" can be anything, bad fuel, bad coil pack, bad injectors, bad crank angle sensor...anything! As long as you didn't feel it and it remains "temporary" I wouldn't worry about it. Until you can see or feel something wrong there is nothing you can do about it anyway.

krasny wrote: ↑Mon Aug 31, 2020 2:50 pm Today I drove the car for some kilometers and the AC does not seem to work also if the car is in movement. If the car is stopped the air is very hot but in movement the air is more or less at the same temperature as the outside.

Thought so. My guess is low refrigerant if the compressor still kicks in. Inspect all the air con components in the engine bay for oil leaks or weeping. You will need to take it to an aircon place to get re-gassed anyway. I found the Schrader valves in the aluminium lines near the front shock mounts are of poor quality and tend to leak. Get the aircon people to replace them. If they know what they are doing they would probably replace them anyway. Again, if they know what they are doing they might take your front grill off and have a look at the condenser on the front of the car. So it might get expensive if they are thorough. I don't know if you have read this:
tips-for-any-citroen-c3-f8/fault-findin ... t3928.html
It's a VERY BASIC look at problems I had with the air con on my car.

krasny wrote: ↑Mon Aug 31, 2020 2:50 pm as you described, with high speed option the fan start in slow mode and the speed increases over time. Maybe is an error and should be only one test.

If the fan ramps up from low speed to full speed then the fan speed controller is working OK. That's the whole point of the test. I wouldn't worry about the low speed fan option. Just a mistake or double up in the LEXIA program. the fact that your options and mine are different would be down to the fact that they are different engine ECU's and how they have written the LEXIA program.

Ozvtr wrote: ↑Mon Aug 31, 2020 10:04 pm "Misfires" can be anything, bad fuel, bad coil pack, bad injectors, bad crank angle sensor...anything! As long as you didn't feel it and it remains "temporary" I wouldn't worry about it. Until you can see or feel something wrong there is nothing you can do about it anyway.

After so long with almost no movement that was my thought, I deleted the error and after restarting the motor everything seems normal.

Ozvtr wrote: ↑Mon Aug 31, 2020 10:04 pm My guess is low refrigerant if the compressor still kicks in. Inspect all the air con components in the engine bay for oil leaks or weeping.

Indeed there are some weeping in the lower part of the motor. I got it checked two times by mechanics and they replaced the oil pan gasket and at first it seemed to improve but after some time it was more or less the same. I'll bring it again to see if there is some solution to that, and after to an AC specialist.

Ozvtr wrote: ↑Mon Aug 31, 2020 10:04 pm If the fan ramps up from low speed to full speed then the fan speed controller is working OK. That's the whole point of the test. I wouldn't worry about the low speed fan option. Just a mistake or double up in the LEXIA program. the fact that your options and mine are different would be down to the fact that they are different engine ECU's and how they have written the LEXIA program.

Good, I'll return the new fan and consider the fan as non-fault. thank you for everything!