Polo 1.4 thermostat - 2001 Volkswagen Golf

Question edited for clarity.
Question moved to model category.

Need year as well ideally

https://www.google.com/search?q=vw+polo+playa+fuel+pump+relay+location

Volkswagen Polo 3 Classic fuse and relay

FuseAndRelay.com https://fuseandrelay.com > volkswagen > polo-3-classic

It is located under the dashboard on the driver's side and is covered by a protective cover. Block location. Type 1.

Volkswagen Polo (mk6; 2018-2022) fuses and relays

Fuse Box Diagrams https://fuse-box.info > volkswagen > volkswagen-polo...

Here you will find fuse box diagrams of Volkswagen Polo 2018, 2029, 2020, 2021, and 2022 get information about the location of the fuse panels inside the car, ...

Volkswagen Polo (9N; 2002-2009) fuses and relays

Fuse Box Diagrams https://fuse-box.info > volkswagen > volkswagen-polo...

Here you will find fuse box diagrams of Volkswagen Polo 2002, 2003, 2004, 2005, 2006, 2007, 2008, and 2009, get information about the location of the fuse ...

Question edited for clarity.
Question move to Polo Category.

Fuse Box Diagram Volkswagen Polo (6r/mk5; 2009-2017)

https://fuse-box.info > volkswagen > volkswagen-polo-...

The fuse box is located behind the cover below the steering wheel. The location of the fuses in the passenger compartment: Volkswagen Polo (2009-2017. The ...

Volkswagen Polo 5 / 6 - fuse and relay

https://fuseandrelay.com > volkswagen > polo-sedan

Complete information on all fuse and relay boxes in the Volkswagen Polo mk5 mk6. Locations, photographs and box diagrams with the designation of elements.
5: 5A Power package control unit
2: 30A Cooling fan motor control unit, cooling f...
1: 25A ABS control unit
3: 5A Cooling fan motor control unit

follow the top radiator hose back to the engine,the thermostat is in that housing unbolt the 2 bolts and take it out

Everything makes sens 1..2..3... what is done is OK.When is cold take a cap off the radiator and start engine run until it overflows then put back the cap?see what happened.

Check fan relay or temp sensor.

Replace the Thermostat.
Make sure your Belts are not loose or worn and therefore slipping.
Check your Radiator Fluid Level.
Check for Coolant Leaks.
Check Water Pump.
Let me know if this helps, or if you have any additional information or questions. Feel free to contact me FixYa.com!

this sounds like a thermostat fault, but also could be the sensor switch to the radiator but is more likely the thermostat, it should be located at the front top of engine, follow the top water hose to the engine and you will find the thermostat housing, also just a heads up, these had a problem when first made, according to the known fixes and problems with VW's the hoses corroded inside and started loosing water, this could be wise to get the system presure checked to...hope this helps

sounds like the plastic impeller has broke on the water pump.

The heater control valve is on the rear bulkhead, it may be that the control cable has seized or the valve is faulty, cheap and easy to replace

Try moving the fan blades by hand to see if the fan spins freely to see if the problem is frozen bearings in the fan motor. Replace the fan motor if it doesn't turn. If it spins freely disconnect the wires and hook the fan directly to the battery using a jumper. If it runs the problem is most likely the thermostatic switch. If it doesn't the fan motor is bad.