Fiesta mk7 1.4 TDCI Radiator Fan Activates on 2nd Gear at 0°C & 80°C Engine Temp - Sensor Replaced

Hello. I have a problem with the radiator fan in the Fiesta mk7 1.4 TDCI.
After warming up and 10 minutes faster, the fan switches on to 2nd gear although outside the temperature is about 0 degrees and the engine is about 80 degrees (all the time off). When I stop and I turn off the car, I work for about 1 minute. Driving a city around the fan does not turn on. Temperature sensor replaced, dpf checked, the computer does not show any errors. Does anyone have an idea of what else can turn on the fan?

I do not know the temperature of the engine like that, and the AC factor. Is it possible to replace the AC sensor without draining the refrigerant?

You can use the Schrader valve under the sensor.

Is it sometimes not working because the filter firing started?

The filter was on the site after connecting the computer. It seems to me that the air conditioning is behind it, I just do not know what exactly.

I have new facts, maybe someone will come up with something. So you can definitely exclude: relay, air conditioning, temperature sensor. The fan does not turn on when stationary, even if it warms up to 86 degrees. The fan switches on when driving after a while, after reaching the temperature of 70 degrees. Simply, the computer gets a signal to turn on the fan at full speed. There are no errors. My question is what else controls the radiator fan in addition to the temperature sensor?

I do not know exactly Fiesta tdci, but Ford TDI have a two-band CHT engine temperature sensor in the head. It is a thermistor sensor, powered by two different voltages, suitable for each range, unfortunately relatively unreliable. Very often, the sensor in the lower range (from -40 ° C to approx. +78 ° C) works correctly, after switching to the upper range (from 62 ° C to 214 ° C) it transfers completely wrong data to the PCM. And for example, in Mondeo and Transit tdci in the softa, the engine overheating protection mode is implemented (so probably in Fiesta too), the following functions are realized:
- it is switched on to the full radiator fan,
- the injection dose is limited (something like in emergency mode, but the "spring" light does not burn),
- the air conditioner is turned off (it can not be turned on).

So maybe check if it is in this car.

On the other hand, if the thermistor circuit is interrupted in the higher range, the radiator fans are switched on permanently (while the motor turns off at short-circuit or can not be started - then the PCM adopts a temperature of 132 ° C).

In my opinion, the CHT sensor is most likely to bruise.

Problem solved . After my own observations I found out that it was something with the DPF (clogged). DPF has been removed and the problem resolved ?. The fan does not turn on. There were a few things on dpf:
- the exchange of oil changed twice a month.
- when replacing the oil from the previous owner, it turned out that it is much too much (ON in oil).
- during firing on the computers each time the process did not reach 100%.

In addition, the car works twice better and has more power.
Thank you for helping everyone