Cooling fan

[mark0]

Hi lads. Just changed the coolant on avensis d4d bleed the system heat coming in to cabin temp gauge stays just under half way cooling fan won’t kick in when I put ac on fans come on but when I turn ac off fans don’t come on left car running for an hour driven for 4 hours no fan coming on I drive a taxi around city and remember before feeling and hearing the fans kick in  is it that diesel fan take longer to come on could there be a sensor problem 

[Duggerz]

It has to be a very hot day in traffic before mine will cut in, diesel cars are more thermally efficient than petrol so they don't require as much cooling capacity for similar horsepower. If the temp is staying in the middle of the gauge then you're fine, or though unlikely, you have a faulty gauge. You can test the sensor work an ohmmeter if you want to be certain, but normally they fail open circuit and you'd get no reading at the dash. Ian

[mark0]

Cheers just wanted to check when I disconnect coolant temp sensor fans kick in and temp gauge in dash doesn’t goes to cold when I reconnect fans stop and gauge in car goes back to half way mark just wanted to see if this was normal 

[Duggerz]

I suggest checking the resistance of the sensor when cold and hot and making sure there's a difference. This may help though it doesn't cover the 1ad engine, I think the testing will be the same. Ianhttp://cloud.tapatalk.com/s/5afff2ad24ef8/COOLING%20SYSTEM.pdf

[mark0]

Cheers pal I will check it out 

[mark0]

Didn’t check resistance yet have to get a new multimeter will have an update when I do does any one know does the 1 sensor do 2 jobs the temp sensor gauge and the fan sensor switch is it done by the one sensor or is there a separate sensor for the fan and one for the coolant temp gauge on the T 25 d4d avensis 

[mark0]

Just to update on the topic fan finally kicked in by itself just as the gauge was under half way checked sensor all good it’s seemed to be a while before the engine really heats up to trip the fan on cheers