C3 Radiator Fan Stays On

[Guest eimaj12000]

My friend has a 2003 C3 HDi which has developed a fault. Basically as soon as the battery is connected the radiator fan stays on until the battery goes flat. We've tried to check for location of relays etc. but can't find the correct one. One thing we were able to try was locating the temperature switch and disconnecting/reconnecting this as well as bridging wires but to no avail.

 

Another forum mentioned some fan controller module which could cause this ? It does sound like a relay sticking on but where is this located ?

 

Any help would be much appreciated

[paul.h]

Could be the temp sensor is faulty and needs replacing (about £20). How quickly does the temp gauge go up and does it show more than 3 bars lit up, although on our car (1.4 petrol) the fan starts whilst still on 3 bars but if connected to a code reader with live data it starts at 96°C which is correct. If you bridge the sensor connector this is like a very high temperature (and may give an error code for an earth fault) since as the sensor gets warmer, its resistance reduces - it would be better to bridge it with a resistor of a few thousand ohms.

 

Ideally, you need to plug in a code reader with live data and see what the gauge is showing, if 96°C or above the fan will come on until it shows less. Haynes wiring diagram shows fuse 8 (20 amp) in the engine fusebox is for the fan and also shows a relay there but not which one. However, on the section on fan removal it mentions a relay may be located on the fan shroud, so could be there.