855 t5 Manual Overheats No Fan!!

[merc85]

Hi there was sitting in Traffic and my fan didnt cut in! car overheated!

Got the car home changed the fan cooling relay but still no fan?

Connected fan up to 12v live from the Battery and it kicks in?

Relay is Good, Fan Motor is good,

Although the temp sender in the stat housing was reading correct could this be somehow faulty? does it tell the fan when to kick in?

As i have a good spare one was thinking of fitting it?

Any helps really apreciated

[nobananas]

I'm not 100 percent sure here but does the fan not have it's own dedicated switch screwed into the radiator ?. Think the temperature sender you are looking at will just be for the ecu.

[merc85]

Really appreciate you reply but there isn't a sensor in the rad, Wish there was, cant belive i didnt spot the gauge kreeping up untill it was too late, drove the car back home 100 miles!! and she didnt use any water finger's crossed the head gasket is ok.

Really need this fan working as i've got to go and see my boy at Gt ormand street hospital tomorrow.

[nobananas]

Scratch that, just looked at the wiring diagram for the engine management and it shows the engine coolant blower motor relay as being switched by the ecu. Could be a stuck thermostat (check that the radiator, hoses etc is getting warm as the vehicle comes up to temperature). Could be a dead ECT sensor, if it's giving a low reading on the gauge it will do the same with the ecu. Can you measure the temperature using a IR thermometer or similar ? There is always the possibility of a blown head gasket but worry about that if all else fails !

[nobananas]

Really appreciate you reply but there isn't a sensor in the rad, Wish there was, cant belive i didnt spot the gauge kreeping up untill it was too late, drove the car back home 100 miles!! and she didnt use any water finger's crossed the head gasket is ok.

Really need this fan working as i've got to go and see my boy at Gt ormand street hospital tomorrow.

How high up the gauge did it get ?

[merc85]

way to high, but she hasnt used any water, on way home. just need that fan working

[nobananas]

Just thought (should have mentioned this earlier !) you have checked the main fuse for the rad fan ?

[merc85]

Just thought (should have mentioned this earlier !) you have checked the main fuse for the rad fan ?

Not sure where this is, Dont think it has one? it's just controled by the relay?

[nobananas]

Another thing, if you have air con and it actually works, turning it on will automatically cycle the rad fan to cool down the condenser. If it works with the a/c then you know all the wiring etc is ok and you could at a push run it in an emergency if the car overheats to (hopefully) bring the temp down.

[nobananas]

Not sure where this is, Dont think it has one? it's just controled by the relay?

No mate, one side of the relay will be switched by the ecu the other side connects power to the fan. There will definately be a fuse supplying the main live to the fan. You should have a 12v supply to one of the thicker cables going to the relay. Can't find where the fuse is at the moment but it will be large ampage fuse.

[nobananas]

Not sure if this helps.
http://www.volvoclub.org.uk/tech/ser...ngDiagrams.pdf

Page 9 shows a fuseable link supplying the fan relay. This may not be in the fue box but something in-line with the supply wiring. First I would see if you have a live on that circuit.

[AndysR]

Got to be something to do with the way the fan is switched on. I am pretty sure it even has a fail safe function of some description. Yours is an M reg isn't? The earlier 850's have a resistor pack on the rad fan itself, maybe the resistor pack itself has failed? As FB has said if you have air con and it works switch it on, once the condensor system gets up to a certain pressure/temperature the cooling fan will come on to control the temperature of the system and that will obviously help by cooling the coolant rad as well..

I'd say that your fault lies with either the resistor pack, if it has one, or the control relay.

[t5 stealth]

there should be a fuse for it,
alternativly..........just wire up the fan to the battery or ignition or on a switch as a temp fix to get you to your boy in hospital,
then sort it when your able to,

[merc85]

Have changed the temp sensor in the stat housing, now the bloody car doesnt seem to get hot enough just ticking over probably cus its now cool outside. will av ago tomorrow morning. I can power the fan up by putting a 12v to the plug, so dont think the fans at fault. Just need to find that fused link.

Thanks for the replys

[merc85]

As above i've changed Fan relay, stat housing sensor, checked all fuses in fuse box all ok.

But funny thing is the rear window wiper doesnt work now it always did do even after the cooling fan rely didnt cut in.

I've obviously disturb somthing.

Still looking for this fuseble link cant see one anywhere?

[merc85]

As above main feed to the Cooling relay had broken, Now New line put in She's good as new. Fingers crossed Head Gasket ok.

Thanks for the diagrams and everyones help,

Also My Son is Doing well in Great Ormond Street since his op

[nobananas]

As above main feed to the Cooling relay had broken, Now New line put in She's good as new. Fingers crossed Head Gasket ok.

Thanks for the diagrams and everyones help,

Also My Son is Doing well in Great Ormond Street since his op

Glad to hear you got it sorted mate and glad to hear your boys doing well.