Abnormal racing fan when you stop after a drive

[MelbMan]

My wifes Series 5 1.6 litre has always "sighed: be it a hot or cold day when you come home and park it in the garage. This is the electric fan running. Normally it's just a faint hum.

Lately it's really racing and much louder. There's two fans between the engine and the radiator. The racing one seems to be the larger one on the passengers side of the car.

The local VW specialist has not struck this before... nor has the local dealer.
THe specialist is talking about replacing the fan (the regulator on these apparently is part of the fan) but that is about $500 for just the parts.
He can't be absolutely sure this will fix the problem. So I've asked the original selling dealers service manager if they have diagnostic gear to check this. THis is the grey area..."book it in for a service and we will look at this"

Has anyone here had a similar problem? This car has done 65k, no other problem and not driven hard. At the moment the weather is cool in Melbourne and between 10 and 15. THe car is not showing as overheating on the temp guage which is sitting normally at 90 deg C.

Thanks
John

[gregozedobe]

I have heard of this being caused by a faulty relay in the fan controller (most common cause) or corrosion in the fuse box (less often). It is also possible it could be linked to a faulty temp sensor or something to do with the air-con.

[MelbMan]

Thanks for your May 2009 reply... at the moment we're just living with what seems like the bigger of the 2 fans operating.... which is noisy.

Just wondering if anyone has any update or clarification on whether a faulty relay in the fan controller could cause this and whether the relay is available as a new spare part?

Thanks
John

[Umai Naa!!]

There have been a few cases of corrosion in the electrical connector that joins the fan wiring into the main wiring harness. Your VW specialist should disconnect it, and check for corrosion on the terminals. He may even find some melted plastic in there due to the heat from the extra resistance the corrosion causes. In this case, the connector plugs would be replaced.

[HiTorque]

My wifes Series 5 1.6 litre has always "sighed: be it a hot or cold day when you come home and park it in the garage. This is the electric fan running. Normally it's just a faint hum.

Lately it's really racing and much louder. There's two fans between the engine and the radiator. The racing one seems to be the larger one on the passengers side of the car.

The local VW specialist has not struck this before... nor has the local dealer.
THe specialist is talking about replacing the fan (the regulator on these apparently is part of the fan) but that is about $500 for just the parts.
He can't be absolutely sure this will fix the problem. So I've asked the original selling dealers service manager if they have diagnostic gear to check this. THis is the grey area..."book it in for a service and we will look at this"

Has anyone here had a similar problem? This car has done 65k, no other problem and not driven hard. At the moment the weather is cool in Melbourne and between 10 and 15. THe car is not showing as overheating on the temp guage which is sitting normally at 90 deg C.

Thanks
John

The fans would have two speed settings - slow when a/c is on and fast - when the engine temp reached a threshold. Start the car with a/c on and fan should start slow perhaps in 30sec. If they run fast immediately - yes, it's either a speed controller or temperature sensor fault. The temp sensor is on the driver side of the radiator, you can disconnect (though not easy to get your hand there) - 3-wire connector and clean it with electrical contact cleaner - both sides, let it dry and then reconnect. I've done all that, but it didn't help until I disconnected the battery and 10sec later connect it again, it's the way to reset the car computer. It doesn't do it any more.

[POLARBEAR666]

You can reduce your radiator temp quite significantly by sealing the gap between the intercooler/radiator assembly and the nose of the car. Air is just rushing in and then blowing over the top of the radiator instead of going through it. If you combine this with foam sealing the gaps to the side and a tray out of plastic or aluminium that stops air rushing underneath the radiator assembly you should see greatly reduced temps.

[HiTorque]

The fans would have two speed settings - slow when a/c is on and fast - when the engine temp reached a threshold. Start the car with a/c on and fan should start slow perhaps in 30sec. If they run fast immediately - yes, it's either a speed controller or temperature sensor fault. The temp sensor is on the driver side of the radiator, you can disconnect (though not easy to get your hand there) - 3-wire connector and clean it with electrical contact cleaner - both sides, let it dry and then reconnect. I've done all that, but it didn't help until I disconnected the battery and 10sec later connect it again, it's the way to reset the car computer. It doesn't do it any more.

Fans started running earlier again and time for 75K km service was due, so the diagnostics revealed faulty small fan with built-in thermostat not switching - at $600+ installed