So I just went for a 15-20 min drive mainly 30 mph roads... pulled up, reversed a couple of times into a tight space and idled for maybe 30 seconds before getting out and noticed the radiator fan was on. Thought it was a bit odd at first as its like 8 degrees out but then realised the ac was on. Turned it off to check and off went the fan. Oil was at 87 and coolant steady 90 like always.

 

This normal? Sorry if its a dumb question, it's been a long time since I've had air con. AC compressor was just changed under warranty.

Yes, very likely to be normal.

Radiator fan action is triggered by refrigerant pressure (which is related to engine bay temperature, ambient temperature, airflow through condenser and how hard the A/C is working) as well as any coolant temperature requirements.

Edited 20 October, 20196 yr by Wino

I don't believe this is normal. I have my aircon on 24/7 and rarely notice the engine fan running. It needs investigating.

@TerFar  Does it happen occasionally that your fan is running and you do notice it doing so?

Rarely noticing something and it not happening are not the same, it just means you might not be aware some of the time it does happen.

In the OP'S case when driving around in these temperatures the fan probably wasn't on, but the combination of slow speed manoeuvres then sitting idling was probably enough for heat to soak forwards out of the coolant radiator into the A/C condenser. This will raise the refrigerant pressure and trigger the fan.

3 hours ago, Roottootemoot said:

@TerFar  Does it happen occasionally that your fan is running and you do notice it doing so?

Rarely noticing something and it not happening are not the same, it just means you might not be aware some of the time it does happen.

Possibly true. But I feel sure that the fan is sufficiently noisy to hear. I did notice it a few times back in the summer heatwaves when temperatures were well over 30 degC, but that wasn't unexpected. 

(This was in a 1.2Tsi/110 DSG with water temp at 90 and oil temp 100, normal on a good run most of the year). 

So gave it a test on the way home. After about 5-10 mins driving with cc on auto, fan wasn't on and took 2-3 mins idling to kick in... 5 mins later was at the shop and it was off. Drove home when it was fully up to temp, couple of slow resi streets and reversed parked. Idled it for about 30 seconds and the fan came on. 

 

From @Wino s explanation all seems pretty normal. I will say in the car with radio on low and windows up I couldn't really hear it. Outside front of the drivers door it was fairly obvious. So unless you get out the car a lot with it running its easy to not notice.

 

Does the fan have multiple speeds? Sure it was a bit louder in the summer 🤔

8 minutes ago, Confused_Cheese said:

Does the fan have multiple speeds?

 

I don't have wiring diagrams for Mk3 Fabia so can't easily check, but I'd be quite surprised if cost-cutting had gone to the extreme of reverting to a single speed fan. Probably either dual speed relay controlled or continuously variable speed solid-state controlled.

On 21/10/2019 at 18:08, Wino said:

Probably either dual speed relay controlled or continuously variable speed solid-state controlled.

Having acquired one of the new-fangled fan speed controllers part number 5J0 919 506 I can confirm that it is nearly identical in function and contents to its predecessor 1J0 919 506M as fitted to earlier Fabias. Just packaged differently with a single connector now. Two relays inside, one for low speed, one for high.

 

 

Seems a bit random when it comes on now tbh, but the fact its not either constantly on and does actually come on sometimes I'm going to take as a good sign and that all is normal and self regulating 😎