A4 1.9 TDi 130 - normal operation for radiator fan

[Dram300]

Is it normal for the radiator fan to be running on start-up when the engine is cold, the outside temp is 10degC and the car hasn't been started for more than 24 hrs.

Temp indicator never goes above the mid point on the gauge. Never has.

More importantly, would the fan running be noisy as the car moves faster?

A4 (B6) Avant 1.9 TDi SE 95k miles

[nickynibbles]

Its not normal on any car for this to happen! There's just no need for the fan to be on at cold start up. Suggest a vagcom scan, you've probably got a coolant temp sensor fault triggering the fan to come on.

[Lex Luthor]

Is it normal for the radiator fan to be running on start-up when the engine is cold, the outside temp is 10degC and the car hasn't been started for more than 24 hrs.

Temp indicator never goes above the mid point on the gauge. Never has.

More importantly, would the fan running be noisy as the car moves faster?

A4 (B6) Avant 1.9 TDi SE 95k miles

The electric fan runs at low speed anytime the climate is on.

[nickynibbles]

The electric fan runs at low speed anytime the climate is on.

It shouldnt be running when the outside air temp is only 10c, the aircon condensor wont need the airflow to disperse the heat.

[Dram300]

Begging my ignorance, but is the radiator fan not belt driven off the engine? An auxilliary fan might be electric?

[nickynibbles]

Begging my ignorance, but is the radiator fan not belt driven off the engine? An auxilliary fan might be electric?

No, radiator fans are electric.

[Dram300]

Am I looking at the wrong thing? At your right hand as you look into the engine bay, about 10" diameter. Seemed to have a belt coming up from base of the engine - could have been an electric drive.

I had a look in the fuse box and there was a Radiator Fan Fuse indicated (Slot 9, 15A) but no fuse in the slot ...

[nickynibbles]

Not so sure on the Tdi what the layout is, drive a 3.0 V6 petrol myself! Certainly my radiator fan is a lot bigger than 10" in diameter, more like 24", and its got a bif electric motor in the centre of it! Either way, the radiator fan is pretty self evident as it attached to the back of the radiator. Is this the same thing your looking at?

[Dram300]

I'll check later, but I'm pretty sure it was belt driven.

[Dram300]

OK, fan checked, electric drive. It was dark last night, and there is a lot of belts around about it !!! Easy mistake to make :Blush2:

Anyhow, I had a look at my fathers TDi golf, similar engine - fan does not start on engine start. Also, on my way home from work, the engine temp started falling at 20-25 mph in traffic (fell from 90degC to around 80ish). Quick to rise back to 90 when the traffic sped up again.

So I can only conclude that a faulty switch or sensor is telling the fan to stay on.

Question remains (relating to my other post) - would the fan spinning make a speed dependent howling noise at 70mph ... plot thickens

[nickynibbles]

OK, fan checked, electric drive. It was dark last night, and there is a lot of belts around about it !!! Easy mistake to make :Blush2:

Anyhow, I had a look at my fathers TDi golf, similar engine - fan does not start on engine start. Also, on my way home from work, the engine temp started falling at 20-25 mph in traffic (fell from 90degC to around 80ish). Quick to rise back to 90 when the traffic sped up again.

So I can only conclude that a faulty switch or sensor is telling the fan to stay on.

Question remains (relating to my other post) - would the fan spinning make a speed dependent howling noise at 70mph ... plot thickens

Its possible it is causing the noise, a spinning fan being forced through the air will make noise. The temp sensor will be pretty obvious to spot, look for a cable plugging into something attached to one of the edges of the radiator, probably on the back so its easily accessed from the engine bay. Disconnect the plug & see if the fan stops. If it does, put a piece of wire into the plugs 2 contacts to bridge the circuit & the fan should start up again. If it behaves exactly like this then it'll definately be the temp sensor.

[Dram300]

Right, found two connectors (yellow) at either side of the radiator - is this what I'm looking for.

I've attached an assortment of piccies which show two fans side by side, a close up of the drive mechanism for the questionable fan, and the yellow connector for reference.

Are we sure the questionable fan has an electric drive?