2005 XC70 - Radiator cooling fan spinning out of control

skuliaxe · Post by **skuliaxe** » 26 Sep 2019, 09:25

I was driving around town a few days ago and suddenly I hear a noise from the engine bay. I opened the hood and the radiator cooling fan is blowing what it seems at maximum speed (like a leaf blower).

First I thought it was an heat issue, but that is not the case. Every time I turn on the car (even in the mornings) the fan goes full speed after about 5 seconds and stays like that until the car is shut off. I'm trying to not drive it in this state but it is the only car in the family and local dealers have a 2 week waiting period.

Does anyone here have any experience with this sort of issue? Searching online did not help and was mostly about the fan not spinning or spinning to slow.

jking4020 · Post by **jking4020** » 08 Oct 2019, 08:50

Sounds like the fan control regulator unit is bad. When they go bad the fan continuously runs. It happened on my car so I wired up a switch to the dashboard. You can buy a new fan somewhere with the new regulator module. something I will do in the future I'm sure. But using the switch is a cheap and quick fix. Just be sure it's at least a 40 amp connection and a high amp switch.

Post by **jimmy57** » 08 Oct 2019, 15:47

In a north American market vehicle the check engine light (maybe Lambda lamp for you) should be on for a faulty coolant sensor. The coolant temp sensor having a fault will cause ECM to run fan at higher speed and continously since the true temp can't be sensed to avoid overheat.

Post by **precopster** » 08 Oct 2019, 17:01

On earlier P2 cars when fan goes full speed on earlier cars you can pull the purple wire from its connector to see if the fan continues to spin as this is the fan command wire from the ECM.

On our 2002 XC70 the fan continues to spin when the purple wire is disconnected so the fan controller is definitley toast.

On later cars the purple wire is integrated into the power connector making it harder unless you break the wire and resolder it.

OnTrack · Post by **OnTrack** » 31 Dec 2020, 03:23

Hi Guys... 2 years ago, my waterpump gave up on one of my 3 XC70. Some cheap workshop had a waterpump with plastic showelwheel moundet.
Broke in to at least 10 pieces. Car had been sitting for 2 years until last week. Put a new waterpump in and filled the engine up to level and had it run and run. Have my own workshop and have lots of other things to do with my cars. 3 XC70 1 XC90 T6 with all the goodies you could get + a Corvette.
The second evening I should start up the mentioned XC70 for a warmup... the battery was drained. Changed it and started the car. Took a 20 minute warmup and test. When back doing other stuff... the fan started running like hell itself. And this was exactly 20 minutes after I shut it off. Restarted the engine and the fan did not come off. No key and it run. Disconnected the battery a while and hooked it up again. Fan run like crazy.
So no wonder the battery was drained the other night. Guess that the fan started running after I left the workshop.
I also have a 4:th XC70 as a donator. Took the radiator fan assembly out of it and swaped it. Now it is back to normal.
As others writers mentions... It is the fan controller that is toast. It looks like a PC harddisk and is mounted on the fan shroud.
Forget trying to repair it. Go to a junkyard and pull out the entire assembly.
It took me some 90 minutes to do the job - out with the kaputt fan and in with the other.
And there is NO relay involved in this fan routing. If it runs like crazy... fan got it´s juice.

Post by **oragex** » 31 Dec 2020, 08:52

On those early years the controller is mounted indeed on the fan assembly. You can also just chop off the two red controller power cables, swap it, and weld the new wires in place (I used soldering iron).