Leaderboard

On the C3 96°C was the start at low speed and high speed would start above this but it never got that high. The temperature was read using a code reader with live data. The thermostat extra sensor is probably another temperature sensor http://www.ebay.co.uk/itm/Citroen-Genuine-Thermostat-and-Housing-with-Sensor-and-1336Z2-C1-C2-C3-/282308298972?_trksid=p2141725.m3641.l6368 Our 2003 C3 1.4 petrol had 2 temperature sensors - one was for the temperature gauge and the other (one wire) gave the high temperature warning at 118°C and put on the engine fan if it was not already on from the gauge sensor. It is the ecu that starts the fan and since you have found it runs ok from the air con and also manually then there may be a problem with the ecu or its connections. I would be tempted to go to a dealer to sort this if you can not find anything obvious.

Haynes do a workshop manual for the C2, as an example on ebay http://www.ebay.co.uk/itm/5635-Haynes-Citroen-C2-2003-2010-53-to-60-Service-Manual-/122270478392?_trksid=p2141725.m3641.l6368 There is also the Citroen service box which can be obtained through ebay. Does the radiator fan run when the air con is switched on - if not the air con will not work ? From the service box procedures, there should be a high temperature warning at 118°C, the thermostat should start to open at 89°C and be full open by 101°C. I could not find the fan settings but on our C3 it would start at 96°C and cut out at 94°C. I do not know what the thermostat wire is for, maybe there is a second temp sensor - if you have a part number for the thermostat it could be looked up.