I own a Fabia 2016 1.2tsi petrol and recently the radiator fans kicks in for about 10-20 seconds then stops, Before kicking back in.  the temp gauge doesn't go above 90°c. 

 

I've included a clip I recorded of the fan on. 

Does it not happen if you switch off the air conditioning?

4 minutes ago, Breezy_Pete said:

Does it not happen if you switch off the air conditioning?

Just tried it and doesn't happen with the air conditioning off. 

I think your radiator fan has a broken low speed. I can take you through a test using a wire link, once I've finished my sausages and mash. 

Are you sure about that, I/ve not checked, but I thought that the fan is only run at high speed when the AC is turned on, the low/high speed is used to control the engine coolant only.

Edited 1 August, 20232 yr by rum4mo
removed an "only" - one is enough.

First thing to do is to check the fuse for the low speed fan function. I don't seem to have mk3 Fabia circuit info, but the owners handbook mentions two engine-bay fuses relating to radiator fan, one large one, #1 and a smaller one, #18. the latter would be my best guess at the relevant fuse, but it seems to do other things as well, so I doubt it's blown.

 

If that is OK, you could double-check the low-speed fan function by shorting pins of the radiator thermoswitch loom connector which is usually a few centimetres above the lower radiator hose connection on the rad. 

I would imagine the pinout is the same as on earlier generations of Fabia, in which case this diagram will tell you what to do:

 

 

Check that the wire going to pin 1 is brown, before proceeding to link 1 & 2, which should bring on the fan at low speed, if working.

 

There is a slight possibility that the fan control unit is to blame, rather than the fan itself, but I think it's very unlikely.

 

It's not only the temperature of the engine coolant that can trigger fan activity, the pressure level of the A/C refrigerant is also monitored whenever it's switched on. Generally, unless ambient temps are extremely high, running the A/C will bring the fan on at low speed only, but if that fails, the pressure will continue to rise until the threshold for full speed fan activity is breached. That's what I think you are currently experiencing.

 

 

 

 

 

 

Edited 1 August, 20232 yr by Breezy_Pete

And down comes the high side pressure so the fan cuts out, pressure rises again fan cuts back in, rinse and repeat...................

 

Good diagnosis Pete 👍

Always easier when it's happened to oneself.

There is a repair option with an external resistor and no need to replace the fan, if it does turn out to be the fan itself, not everyone's cup of tea though.

See: https://www.briskoda.net/forums/topic/404143-radiator-fan-repair-courtesy-of-vortex-here-and-uk-mkiv-forum/