00 V70 No power to the radiator fan

[tulipandthistle]

Hi there.

I have no DC power going to the radiator fan. Even when I switch the Airco on DC power comes in.

Any ideas what I can check?

[Marmitespreader]

Phase I or II?
There is a temp sensor somewhere in the engine which switches power to the rad fan when at a certain temp.
My rad fan will only come on when engine reaches a certain temp, its never been on since ive had the vehicle, it just doesnt overheat, it doesn't come on when I power up my A/C

[LJD]

Its very rare my fan ever comes on !

[Brendan W]

If you want to check fan function you could leave it idling on a warm day although if you have a diesel it could be a very long wait.
To check fan system on some cars, I pull the temp sensor plug and that usually frightens the daylights out of an ECU and puts the fan on and can be accompanied by various engine management warnings which may self erase or not after a few cycles.
I have not done this on the V70 D5 as the temp guage is well behaved and meddling is risky.

[tulipandthistle]

It only ones overheated in city traffic on a very hot day.

Should it not be running when the aircon is switched on? The Aircon is not working on this car. It gives a low pressure fault, but when I was looking at that I noticed that the fan didn't go on. I measured the thick red wire and this gives no DC.

I have a diesel. I will try the disconnecting the temperature cable. I have a DICE and VIDA so I can erase the codes.

Thanks guys, I will report back.

[Longhouse21]

I think within VIDA you can peform diagnostics to bring the fan on at pre-set / test temperature points. I don't have access at the moment to my installation (2011) but I'm fairly sure that you can "force" the fan in the same way you can "force" items like the EGR, TCV (engine mounts), etc. Steve

[tulipandthistle]

cheers longhouse21, I will see if I can find it.

Yesterday was a very rainy day but today looks a lot better for working on the car!

[mikealder]

An earlier post of mine might be of some help for testing your rad fan, if the decade box is too costly or you don't have access to one a few pence for a couple of resistors from Maplins will be all you need:

Originally Posted by mikealder

If you have access to a decade resistance box this will be easy, otherwise a trip to Maplins to purchase some resistors will be required, they only cost a few pence each.

A 155 Ohm resistor equates to an engine temp of 106 Deg C, connect this in lue of the coolant temp sender unit with the ignition switched on, the radiator fan should run at slow speed.

A 125 Ohm resistor equates to an engine temp of 114 Deg C, connect this in lue of the coolant temp sender unit with the ignition switiched on, the radiator fan should run at high speed.

Obviously with a decade box you can adjust the resistance to suit the above values, if you do take this route avoid going below 105 Ohms otherwise the ECU will record a fault as it sees the coolant temp sender going outside its design parameters - Mike

[Longhouse21]

Location for fan tests in VIDA:

Diagnostics/vehicle communications/ECM/activations/engine coolant fan then check poosible activations.

I think from here you can perforn similar tests to the tests suggsested by mikealder, although the resistor tests represent a true point to point not a software force.

Steve

[tulipandthistle]

Cheers Mike and Steve,

Yep with VIDA I can switch on the fan, no bother.

I noticed that the fault code for low pressure for the aircon is present.

Could it be that the fan for the aircon is shut down because the is too little refrigerant in the system?