Hi there, I am having a nightmare with my dads octavia. Its a 1.6 avu engine, 2000 model. Basically the fans come on as soon as you turn the ignition on and you have to disconnect the battery in order to stop them. Now this started when he overheated last week, which was put down to the elecrothermostat, changed that, seems to open and close fine, but I was told this would also cure the fans, but alas no. Now im also told there is a fan run on relay, which may well be knackered, but Im buggered if I can find it, on a golf its number 181 in location 13, but im well and truly stuck, any advice would be great. Cheers.

i expect the fan switch has shorted out.

The one on the rad? I thought that would not work if the ignition was off?

i cant think of a good way of explaining this.........

they dont normally...... but it does work for a set period of about 10mins after the engine has been switched off.

try unplugging the the fan switch then turning on the ignition to see if the fan still come on or not

Right o, im off to do that now. Cheers.

One more thing, any ideas where the relays are? Ive got a couple under a black cover in the engine compartment, 4 or 5 under the steerring column, any more anywhere else?

Tried unplugging the fan switch and it doesnt change anything, fans come on and carry on regarddless!!!

It can be,

Faulty fans (my educated guess)

Fan relay unit (under n/s chassis leg under battery (gets water in it)

An air con fault (maybe excess pressure)

Any fault codes you know of?