Advice on radiotor fan constantly on.

[maddar88]

Thanks for taking the time to read this.

I have an Astra J that today started to have its radiator fan constantly on when the engine is running. I see no coolant leak, no dreaded oil mixing. Ran OBD scanner with no codes thrown. The fan switches off as normal when the engine shuts.

Can anyone lead me to a possible fault?

[njw1]

Silly question but is the AC switched on?

[maddar88]

njw1 said:

Silly question but is the AC switched on?

Thanks for the reply, it isnt. I had the car bonnet up while the engine was running and can see the fan.

[cknotty]

Is the fan running at high speed? A faulty thermostat is pretty common on these (at least on the petrols). This would also trigger the orange spanner light or Service Vehicle Soon message, but these fault codes don't come up on basic OBD code readers.

[stevieturbo]

maddar88 said:

Thanks for taking the time to read this.

I have an Astra J that today started to have its radiator fan constantly on when the engine is running. I see no coolant leak, no dreaded oil mixing. Ran OBD scanner with no codes thrown. The fan switches off as normal when the engine shuts.

Can anyone lead me to a possible fault?

What coolant temperature are you seeing on the scan tool ?

If it's a generic OBD code reader, bin it and get a proper one you can see live data etc

[maddar88]

stevieturbo said:

What coolant temperature are you seeing on the scan tool ?

If it's a generic OBD code reader, bin it and get a proper one you can see live data etc

Anywhere from 50 to 70 degrees, its not touching the middle 90 where it usually is when running fine. Mine has is small OBD scanner but shows no codes .

[maddar88]

cknotty said:

Is the fan running at high speed? A faulty thermostat is pretty common on these (at least on the petrols). This would also trigger the orange spanner light or Service Vehicle Soon message, but these fault codes don't come up on basic OBD code readers.

I was expecting as such or a message on the dash, but nothing at all.

[E-bmw]

Fan switch on the radiator goosed or wiring fault on the switch wiring (obviously assuming it is switched on by switch) would be my first thing to look at.

If it is not then the wiring diagram would need to be consulted and (likely) the ECU output checked.