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cooling fan not working.


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basically the cooling fan doesnt come on at temperature. ive shorted out across the temp sensor and the fan came on. so that points to a faulty sensor. changed it but still have the same problem. this is the third sensor now. the car has air con so i thought id see if it works when the air con is switched and it does.


when i short out and bypass the sensor i notice that theres a relay behind the battery that clicks. it doesnt stay on just stops and starts as i short out the sensor. im guessing that the sensor get up to temperature and sets the relay on to start the fan as it run off of bigger cables than what is plugged into the sensor. the a/c must also link onto the relay to operate the fan when you turn the a/c on.


so if this is a brand new sensor that is apparently working why isnt the fans coming on? i tested the old sensor by putting it in some water about 99degress c and tested across all the terminals but there was no contunuity anywhere. i havent tested the new sensor though as im not too sure if you have to test for contunuity or a certain resistance.


alslo i checked that there wasnt an air block behind the sensor by squeezing the pipe which forces all the air and fluid back into the tank. plus when i changed the sensor fluid went everywhere twice so its obviously working.



any help is appreciaited as i cant really drive it. unless i turn on the a/c for every journey or when its up to temp. lol.



cheers :cheers:

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You could have a crack with an infrared thermometer.. but not really easily.


If the pipe gets hot.. then I think you should test the sensor in the same way you tested the other one. Boiling water and a meter across the terminals set to continuity (or resistance).. it'll either beep when it switches or the resistance will go from nothing to zero (yes, nothing and zero are different ;))

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well this is the third sensor and its the same problem so im not too sure. ill try the thermostat anyway because thats letting the hot water into the rad and to be perfectly honest if that pipe was 60degrees you wouldnt want to hold it let alone it being at 90. where are you in essex stu? is it colchester?
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It's my co.


I used to live in Upminster..



were straying from the subject of cooling fans now. i looked into ox technology once. was thinking about doing an apprenticeship with then but instead became a sparky. if im still having trouble after i change the stat tomorrow i might let you have a look at it.

the ecu doesnt control the fan does it? its all run off that temp switch?

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Yes it's all from the fan switch... if you have a/c then there is an additional circuit to switch the fan on half speed..



yeah thats working. it must latch the realy on and the fan switch circuit must also latch the relay. seems strange but ill try the stat and post again soon.




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still dont bloody work.


changed the stat and the fan temp switch. i tested them too. put a saucepan of water on the hob and put a thermometer in it. it went from 60 to 99oc and im not too sure if it was worth trying lol. the fan temp switch didnt get a connection across any terminal and the stat didnt seem to move but i put it on the car and run it up to temperature and it opens cos the pipe gets f##king hot.


might try the relay that sits behind the battery and maybe another new fan temp switch but im not sure



once again,,,,,,help

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