AYates

Hello everyone, Having an issue with overheating on my 2014 A3 2.0TDI. Every now and then It'll over heat but if i turn the blowers on hot and full it runs at normal temp. Coolant hoses to the radiator feel cold as well even after a long journey. I believe this is the thermostat does anyone know the location of the thermostat and if it is fairly pain free to tackle on your own? Thanks in advance