My Octavia VRS Mk3 petrol had overheated without any warning.

Refilled reservoir - now shows oil at 105C dropping slowly down to 98C when free wheeling.

Fan not running after stopping from oil at 105C

Suspect that the fan is not running as it should and cooling is by ram induced air flow only.

BUT CANNOT FIND where is the relay ? ?.

I read it is actually a combined controller and relay in a plastic box

BUT WHERE IS IT ?

and any data about it ?

I found service manual for TDi but not for VRS TSi ? ?

Any help with this problem will be VERY much appreciated.

Thanks

Yep agreed with others that the dash temp only ever shows 90C - so no warning of impending overheat until coolant level is way down -

By which time it is boiling NOT CLEVER to use a gauge with markings to NOT show actual temp !!

With the engine switched off, check the fan at least spins by hand. Check the fuse shown above.

Then its a case of making sure the thermostat is operating correctly too.

OK Thanks for response.

That fuse was checked OK - but I think it only supplies power to the control unit (and other units which still run OK) to switch the coil of the fan relay which is somewhere else and may also have a fan current fuse..

The only info I can find is what is shown on Ebay as replacements which look like a small longish plastic box/housing - but nothing about where it is located.

Basics question - is there a separate relay?

Quite often on modern cars the power is switched by a semiconductor in the module - the cue will be the rating of the fuse that supplies the module, a small rating probably means it powers on ly the module but a higher rating means it powers the load (in this case the fan) as well.

Sounds like you need a wiring diagram - which someone here might have and can share?

If you switch on the AC, does the fan come on?

Maybe coolant temp not high enough.

Hi, many thanks for responses.

Will try AC switch on - is it that it is known that the AC overides the temp controller and the fan should come on regardless of water temp ? and only when engine running ? or is it that the additional heat / temp in the adjacent A/C radiator should trigger the fan to run more often ?

It boiled out of reservor so water temp must have been too high - but useless water temp meter still said 90C - next job will be to convert to a proper mater so water temp can be monitored !.

Note oil temp varied according to engine power demanded (up) and air speed (down) which 99% meant the fan was not ever running and it was just ram effect air flow cooling the radiators

The fuse F4 at 5A I don't think would be enough to power the other items listed and also the fan.

So yes agreed it could be a semiconductor in "the module" rather than a relay but anyway the module is not part of the fuse panel - it is somewhere all I can find is a reference that it is on the passenger side towards the back - but I cannot find anything - would expect the actual fan fuse to be accessable and way more maybe 20A - 30A ? ?.

Please see ebay -

"skoda octavia radiator fan module"

Yes a wiring diagram would be gratefully copied.

I would espect all 1.9/2L petrol would have the same - as I said I could only find for TDi which does not give any help.

Thanks for support.

A/C mediated fan action tends to be triggered by refrigerant pressure levels, not engine coolant temperature.

I suspect your fan control module may be built into the radiator fan. Let me know the VIN if you'd like me to investigate.

Hi Breezy_Pete,

Thanks for response.

Maybe that is why I cannot find it ?

To be at/within fan It would require (minimum) 3 wires control/0/12(from fuse somewhere) but I think it is only 2 - not easy to check as very tight around there.

VIN TMBK E9NE 2F01 4195 5

Type OCT.COM RS FS16/2.0M6F

Deliv 2015-01-05

Any help much appreciated.

Circuit diagram source anyone ?

F4 at 5A I don't think is near enough for controls AND fan motor - anyway it is OK.

Thanks

That VIN gives the part number(s) shown in this ebay listing for your fan. I've highlighted the four-way connection block. Two high current wires, two slim ones. Look for this arrangement on your car to confirm. Circuit shows J293 radiator fan control unit, and radiator fan V7 as a single schematic block. Optionally with a second 'daughter' fan powered from it too.

Fuses involved are a 50 Amp fuse in fuseholder A position 5, the rightmost fuse with wire coming off it, front of engine bay fusebox (permanent power feed for fan) as well as the one you have already identified which is more of a 'wake up we're running' feed.

The other wire on pin 3 of the pictured connector is from engine ECU, the control feed for the fan module.

This ebay listing was just used for a quick screengrab, not as a recommendation of where to buy from.

Hi Breezy_Pete,

Many thanks for this and circuit screen grab.

Away just now but I think this should enable me now to trace, test and fix.

Thanks again