Hi I have a 03 mk1 octavia tdi estate and the cooling fans dont seem to be coming on. The larger fan has been replaced as the motor was knackered.

Both fuses are good.

Both fans come on with the air con.

I tried testing them manually by shorting the wires at the temp switch in the rad but nothing. I tested voltage of the feed (plain red) but nothing. So does anyone know where the feed (the plain red cable )to the temp switch comes from. .

I tried a cable from the battery to the phase 1 fan cable (red/white stripe) in this block and the fans worked.

I suspect there isa poor connection somewhere in the feed or is there another fuse to look at?

Any ideas, or help welcomed

Cheers

It's probably a faulty fan controller which is located under battery tray - just follow the fan cables back.

Hi thanks for repling so quickly.

Is there any way of checking/testing for a faulty control unit?

I've followed the suspect wire back as far as the loom which goes behind the battery plate in the opposite direction to the control unit.

Should there be a voltage at the temp switch?

I've checked continuity at the control and there are 3 feeds leading back the battery fuse block all with good voltages.

Cheers

Simon

For the stage 2 fans, if at the controller the red/yellow wire goes high it should turn on the stage 2 fans (thick red/black wire).

Chased the feed for the temp switch back to its join to the feed cable from the battery. It is joined to the fused solid red cable whi h also feedz the control unit and the join/splice is in the loom under the battery plate. And this is where I cound the fault. All working now.