Intermittent Radiator fan

Hi All,

I have a 2002 c3 1.4 sx with aircon. The radiator/cooling fan seems to be intermittent. I have done a little investigation into this and have the standard 2 wires ( LIve/Earth ) which are both reading properly and then I have the three thinner wires from the ECU, now these are the ones of interest. The first wire is violet when it goes in the connector and green when it exits and this one , when the fan is working and also when it is not working ( but should be ) reads 11-12v. Now the next two wires are Blue in/grey out . white in/ yellow out,and both of these when the fan is working read under 1v, whereas when the fan is not working ( and should be ) they both read between 11 and 12 v , as if they were shorting out to live. Any ideas??

Oh I have replace the sensor on the top of the head to the right of the engine ( when looking in from the front )

Hope all that makes sense!

Cheers
Kieron

Hi Kieron

From the Diagram I have for petrol with A/C the Engine bay fuse box and the engine ECU have a hand in controlling the fan which widens your search for problems.

The colours don't match yours unfortunately, but there are 3 control wires. One from the engine bay fuse box (BSM) and two that go to the engine ECU.

A quick check and clean of the connectors to engine ecu and BSM would be a good start.

Cheers for the reply...will look into that once the wind and rain have dropped here! Tke it it would have a realy some where as well ( on the bsm ) if so is it changeable....also what might be causing the change from very low voltage when working to 11-12v when not working?

Cheers
Kieron

Tke it it would have a realy some where as well ( on the bsm ) if so is it changeable....

Yes, there is a relay in the BSM, but as for it being changeable, I don't know. Some of the BSMs open up easily and others are sealed.

There have been attempts at replacing a relay in the BSM, but it turned out it was more than just the relay busted and a second hand BSM was fitted in the end. The post about a relay replacement by bill sutton is here.




https://citroenc3owners.com/citroen-c3-t ... s-t36.html