Viscous fan fault

[tasobb]

Hi all , searched around but couldn’t find anything, trusty old D3 2006, started to switch viscous fan on and off, mainly in arvo and usually it just stays on in late arvo. Touring around Aust and towing a caravan. I have had the cooling system pressure tested, car serviced and washed out radiator etc. is there a seperate coolant temp sensor for the ecu/viscous fan?
the eng temp seems normal on the gauge.
Appreciate any feedback.
Tasobb

[matti4556]

Does the auto tranny circulate fluid through the radiator for cooling?
It may be the tranny fluid is hot so its telling the fan to help out.
Not sure of this theory though but a read of the manual might talk about this - I think I saw it just the other week when I was reading the manual about towing?? - Matti

[BobD]

The temperature gauge does not move until well after the fan is full on. On mine the gauge moves nearly to the top at 108 degrees and the fan starts increasing speed from about 100 degrees or a bit less. You need a GAP 11D to monitor the actual temperatures to see what is happening. It also tells you the fan speed which you can see starts to increase as the temperature rises.

You don't hear the gradual increase in fan speed and only really hear it when it is fully locked on, which means that the coolant (and transmission) temperatures are pretty high so you need to back off and preferably change down to get the fan revs up. If it keeps rising after the fan is locked on the temp gauge will go the top in two steps. It stays on normal until then.