This is my first post so hello to everyone.  I have a 1.4 2006 Fabia and both cooling fans run permanently, even with ignition off, when its stone cold and AC off or on.

 

Since both fans are running, is it most likely to be the thermostat? Or investigate the control unit first?

 

If thermostat, just to check thats the right one in the photo. Its on a plastic housing when the radiator hose joins the engine, facing to the front?

 

Presumably I could pull the electrical connector off - if that stops the fan then it would confirm it as a faulty thermostat?

 

Many thanks

 

 

 

 

 

 

350D4670-AA60-4B5B-A491-7250B5CF8E39.heic

It won't be anything to do with the thermostat, I don't think.

Probably a stuck relay within the fan control module, which hangs off a bracket on nearside chassis leg near bottom hose radiator connection.

 

Edit: looks like this

 

Edited 5 December, 20241 yr by Breezy_Pete

Many thanks Breezy Pete.  So need to get access from above to get to the where the unit connects to the carrier? The 30a and b pins are presumably the battery side for the two fan circuits so i'm looking for continuity between either of those and either of the 1 or 2 pins on the 4 pin side for stuck on?

Access from below may be easier, not sure.

 

Yes, 30a to 2 or 30b to 1 will be shorted, I think.  May find that hitting the outside of the module unsticks it. 

 

On this scribbly circuit of the internals of the FCM, the connections on the right of the sketch are 30b, 1, 30a and 2 reading from top to bottom, I think, looking at the terminal sizes on the side of the relay module.

 

Edited 5 December, 20241 yr by Breezy_Pete

Thanks.  I've pulled the cables on the 4 pin side from below and checked for continuity - doesn't seem to be an issue. No continuity between any of the pins. Any thoughts? Thanks again for your help - very useful!

Only other scenario I can see resulting in fans on with ignition off is a short to earth on one or other of the wires connected to terminals MOT1 or K1, causing stage 1 relay to be energised when it shouldn't be. 

Was the 6-way connector plugged in, or not, when you were testing pin-to-pin of the 4-way plug on the FCM?

Could be the radiator thermoswitch stuck on? That pulls connection MOT1 down to earth I think. Could unplug the thermoswitch connector at the radiator and re-try.

Would be unusual I think, because in cars with A/C that thermoswitch is only carrying relay coil currents, not the full fan power.

Thanks.  I left the 6 pin connector in when I tested the 4 pin side. Presumably i can reconnect 4 pin, pull 6 pin and reconnect battery and see what happens. 

 

 

Thanks. So thats the thermoswitch in the hosing where top rad hose joins engine? If so, I think you're correct, the wires dont look like theyll be carrying much current.

If the 6 pin connector was in, then if there was a trigger for the stage 1 relay, you should have measured the resulting short between 30b and 1, I would have thought.

 

Yes, try 4-pin connector in, 6 pin out and see what happens.

 

86a is a fused permanent supply from one of the blade fuses in the battery fuseholder, 86b should only be 12V when ignition is on, MOT1 & 2 are from thermoswitch, K1 &2 from the HVAC control module in the cabin.

 

1 minute ago, GKP001 said:

Thanks. So thats the thermoswitch in the hosing where top rad hose joins engine? If so, I think you're correct, the wires dont look like theyll be carrying much current.

No, thermoswitch is radiator mounted, 10-15cm above bottom hose connection.

That schematic ^ doesn't include the 12V conns of the 6-way or the K1/K2 ones, let me find a page showing those, for completeness.

pulled 6 pin side, reconnected 4 pin side. No fan with or without ignition on.

Good progress, try thermoswitch 3-pin connector out next, then reconnect 6-way.

OK, some progress.... with 6 pin and battery connected i could find continuity across the two small pins on the 4 pin side. I had a good pull and poke at the thermoswitch but i cant get my hand in a good enough position to get the connector released. But, then I went back and rechecked and the continuity across the two small pins has gone...... So fan is off now with or without ignition.  Feels like progress - looks like there is something up with the thermoswitch connection. I'll take it for a run later and see if i can get fans to come on! Many thanks again

Might be wires shorting at the cable entry of the thermoswitch connector, rather than one of  the switches being welded shut.

Which you've now disturbed and cleared the short? 

It is a horrible spot for access, and the connector latch is probably facing in an unhelpful direction.   

 

Last time I was in that area on a 9N3 Polo I used to own, the wiring just outside the thermoswitch connector was a right mess.