Engine fan constantly running

[koosintea]

Hi all!

I've just picked up a nice V70 D5 from eBay. I really should know better...

While I was checking the oil I noticed a disconnected connector...the other end was right next to it so I plugged it back in.

The result was that the engine fan runs constantly, even with the ignition off, and even an hour after the engine has stopped. Guess that explains why it was disconnected!

Has anyone else experienced this? I can only think that the temperature sender is borked...

[Luxobarge]

If the temp sensor was faulty you'd be seeing other symptoms, notably the temperature guage would be reading wrong.

Favourite would be a stuck relay I'd have thought - I think it's in a panel immediately above and behind the radiator - although I don't know the diesel models well, it may be different.

[960kg]

How does it drive????

If the fan runs forever it is usually an indication of a faulty MAF!

Try to get the error codes?

[GEORGEROV]

[QUOTE=koosintea;1544078]Hi all!

While I was checking the oil I noticed a disconnected connector...the other end was right next to it so I plugged it back in.

The result was that the engine fan runs constantly, even with the ignition off, and even an hour after the engine has stopped. Guess that explains why it was disconnected!

Has anyone else experienced this? I can only think that the temperature sender is borked...[/QUOTE

Dont know a lot about this model but on a lot of cars there can be test connector plugs under the dash or in engine bay which are only connected when doing certain tests on components . Is everything else on the car working correctly when this is disconnected ? . If so then that is probably the answer .

[Chris_Rogers]

As it's a D5, maybe better to go to the 2000> forum, once there search for faulty fan controller.

[KBB]

I'm assuming that this is a phase 2 running EDC 15 and will be fitted with a cooling fan control module located on the cooling fan frame. The key clue here is that even with the engine off the fan is running, a key indicator that the control module itself has failed. If the fan were to run at key on with a cold engine then the fault could be with the coolant temp sensor or its associated wiring or the A/C pressure sensor and its associated wiring, both of these possible's can quickly be eliminated with a scan tool and access to live data.

In over view the control module receives a permanent live feed via fuse A8, in side the module is a transistor which is a similar set up to the heater blower fan circuit. The ECU monitors engine coolant and at 100deg will send's a pulse width modulated signal to pin 4 at the cooling fan module this signal controls the base current of the transistor and then switches power to the cooling fan. By using a varying signal this can control the speed of the fan without using traditional relays.

The other control circuit that will force the ECU to command the cooling fan on is the A/C system pressure. When the AC reaches 3100Kpa the ECU will command the cooling fan to cool the A/C condenser. This is where live data is useful if with a cold engine key on engine off and live data showing a ECT over 100deg then test the ECT and also its 5v reference voltage and a ground. Likewise under the same condition if you look at A/C line pressure and its over 3100kpa then test the sensor and also its 5v reference voltage, signal voltage and ground.

In this case I suspect the transistor has blown and is creating a direct feed to the fan motor.

Hope tis is of help!

[960kg]

OK, so i know this is a Diesel motor but it seems to have the symptoms of a petrol motor also!..........so could the problem be an aftermarket MAF affecting other systems???

.......anyway have a read of the following LINK

It is also here if you have forgotten how to work it!

http://www.volvoforums.org.uk/showth...ht=coolant+fan

Read it very carefully word for word and you will see despite what motor he has the fan runs continously after he has switched OFF the engine!!!!

The answer to his problem IS in post Number 8 but especially Number 21 & 28

[Slackey]

Did anyone read the links that Keith posted? He actually may have a point about the MAF. The link he posted shows that it was a tried and tested solution to a fault with what appears to be identical symptoms to the OP.

I for one will be interested to hear what the final outcome of the OPs problem is. If it is the MAF then maybe some people should being helping themselves to a large portion of humble pie

[KBB]

In his defence on the V40 T4 a MAF fault would cause the cooling fan to run for 10 minutes for a cold engine start up both for a signal too high and a signal too low condition DTC.

The second condition for fan run on after a hot shut-down is when the coolant remains above 115 deg and it would run on for 2.5 minutes.

The D5 will not have any cooling fan action for a MAF fault.

[strbryan]

Originally Posted by Slackey

Did anyone read the links that Keith posted? He actually may have a point about the MAF. The link he posted shows that it was a tried and tested solution to a fault with what appears to be identical symptoms to the OP.

I for one will be interested to hear what the final outcome of the OPs problem is. If it is the MAF then maybe some people should being helping themselves to a large portion of humble pie

The link 960kg provided was with reference to a petrol 1998 Volvo V40 Turbo So unless the p2 D5 has the same running characteristics as the early petrol Volvo's I doubt anyone will be eating any humble pie..