Cooling fan issue Audi cabriolet 2.8

[quattrostyle]

Well the fan on my cabriolet doesn't work for a long time now. Have had the wiring to the sender checked and it's fine. When I bridge the pins in the connector the fans work perfectly but it doesn't work from the sensor. Fitted a new one last summer and another second hand original one now but it makes no difference.

What could be the problem and the cure for this?

[quattrostyle]

boing, anyone got a clue?

[Tonks4x4]

If you bridge out the wire on the sensor and it turns on the fans everything is ok.

It can only be either the new switch is faulty or there is no flow of coolant. is the thermostat ok?

[quattrostyle]

tried 3 sensors in total, should they all be faulty? I believe the thermostat is ok, temperature is good but runs up as the fans are not working. Coolant is flowing into the reservoir bottle trough the small pipe so that should be ok aswell?

When the fans are running constantly on normal speed the engine temp on the highway is about 80 degrees and 90 degrees when the fans are switched off. Without the fans running the temperature reaches 100 degrees easily in city traffic.

[Tonks4x4]

Do the fans not come on if you let it get above 100°C at all?

Other things to check....
If you have fitted plasma dials or replaced the gauge faces the needle may not be in the exact same position so could be showing hotter than it is.

If you have replaced the MFTS then this could be reading a false figure.

And when you replaced the fan switch in the bottom of the radiator I am guessing the water flowed out easily and there is no obstruction inside the rad?

[quattrostyle]

no they don't kick in at all, don't want it to get above 100 degrees anyway, it's still a weak V6

Never replaced the faces nor fitted plasma dials, never changed the MFTS on this car either.

Fluid came out easily enough when I took the sender out, although now I think of it maybe not as easy as on my 5-pot cars.