I just bought a second hand 2008 octavia. It test drove with no issues. The day after was really hot and the coolant warning light came on, level was fine so seemed to be a temp issue and low and behold there was no sign of the radiator fan coming on at all, the engine did not overheat though according to the gauge it sat comfortably at 90, although the coolant got so hot it ended up damaging the coolant reservoir and put a small hole in it. Since the air temperature is a bit lower today I haven't had any coolant heat issues but still no sign of fan working. 

 

Both radiator pipes are warm so the pump is working, and it appears the thermostat itself is working, as the fan still did not work with the thermostat removed. Any other ideas as to what it could be and how to test them? Thanks in advance

Find someone close with VDCS and they can test the fans for you, look in VDCS Map section.

 

Is your air con working?, if not the fans don't work when the air con is on either.

 

Hope this helps,

 

Trev AKA Aston_Bodger

Coolant warnong light is usually a problem with the level sender, well documented on here, in 14 years of driving a MK1 and MK2 Octavia I have never known the electric fan(s) to cut in for engine cooling, only for the air-con, that wasnt working for a decade on my MK1 as I damaged the pump drive spindle trying to remove the broken E/M clutch and the fan never ran after that, gave me the shock of my life when I finally replaced the air-con pump and got the system working.

 

I think you may be chasing a fault that is not there and overlooking one that is, with VCDS its very easy to test the fan function and see if any relevant coolant temp or level sensors have played up.

6 hours ago, J.R. said:

Coolant warnong light is usually a problem with the level sender, well documented on here, in 14 years of driving a MK1 and MK2 Octavia I have never known the electric fan(s) to cut in for engine cooling,

 

I changed the radiator on my old 1.416v Octavia mkI (which I think is the same engine as the OP's 1.4 as 2008 predates the 1.4tsi in an Octavia) and after purging air from the nice fresh coolant I ran up to full temperature waiting until the fan started to come on (I think it started at slow speed first if I remember correctly). At no time did the temperature gauge go over 90! 

 

Also stuck in lots of lengthy traffic I have detected the fan running on this car.

 

Key question - when this was going on, was the main radiator core hot? If cool/tepid I'd suspect a waterpump impeller or stuck thermostat issue

Edited 21 April, 20197 yr by bigjohn

My comments were regarding diesel engines so should be ignored, every petrol engined vehicle I have had the fans have cut in at one time or another usually at standstill or in crawling traffic in summer.