Engine radiator cooling fan won't stop running

[2002V70XC]

I'm trying to diagnose the issue with my car's radiator fan. It wouldn't stop running!
It happened on a super HOT summer day in Australia. The engine cooling fan decided to keep on running after the engine has been shutdown and it wouldn't stop. I decided to disconnect the fan after letting it run for a few hours. Just to be clear, I disconnected the connector at the top of the fan shroud next to the radiator to make the fan stop running. Now, it would start running (at high speed) every time I reconnect the connector.
My temperature gauge is working properly so I don't think its the Coolant Temperature Sensor at the thermostat. I have no check engine light so it can't be the thermostat?
I've scanned for codes with Vida/Dice but didn't find anything related. I've read through threads about this issue but haven't found a clear answer.
Does anyone know of a way to diagnose it so that we can define if the fault is at the fan controller?

The one on my car looks like this one:



Cheers
KN

[Aussie70]

G'day,
have you tried disconnecting the battery for a while, maybe a reboot would help?

[AKAMick]

Fan relay could be the problem

[Aussie70]

yep, see here
http://www.volvoxc.com/forums/showth...ommon-problem-!)

[2002V70XC]

yep, see here
http://www.volvoxc.com/forums/showth...ommon-problem-!)

Great thread! Thanks
I'll do the "purple connector" test today and see. The last time I did the test I think I did try and remove the purple connector before connecting the power connector but the fan still started running. I'll test it again to make sure!
My guess is that the controller is faulty so I might have to have an expensive Xmas

[jaip]

my fan used to be on more than I felt it should be, since changing the thermostat It now seems to be on lots less

[2002V70XC]

my fan used to be on more than I felt it should be, since changing the thermostat It now seems to be on lots less

According to many threads that i've read about thermostat/ ECT sensor, I think the thermostats on these P2 would throw a CODE/CEL when they fail.
My thermostat is still alright and I can't afford to buy the whole thermostat unit after spending $440USD on the engine radiator cooling fan. Plus I don't want to touch the coolant system (if I don't have to) since I just did a full D&F not long ago after replacing the expansion tank.
This Volvo Engine cooling fan design is not good for us - the DIY people. I wish that the controller unit could be repaired/replaced.

[monochamus]

My car (2006 xc70 2,5T,83k miles) now have the same issue.
After hit the gas pedal, the fan stays on at high speed and never stops.
So, In this Events order, I scanned the car with vida and throw a fan module error code, missing/ no signal . I went to dismantler and get one from an earlier S80; the fan has the same shape but different bosch part number. I Installed it. So I plugged VIDA and erased the codes. The fan return to work properly. By maintenance, changed thermostat housing and changed Coolant volvo original. I took the car to a volvo mechanic and he replaced timing belt and all related, new brake and steering fluids. And when returned to home, I hitted the gas pedal at 90mph, so when arrived to Home, the fan was working at high speed again. What a PITA. Where do you recommend to follow? I am clueless....
Many thanks in advance

[monochamus]

For further info, my A/C is not working properly. I refilled it on january, this year, and was empty on march. Could it be related? I scanned it with vida, and it throw an error code related to gas refrigerant sensor