Peugeot Partner 2.0 Hdi Cooling fan not working

[Element]

2.0 Hdi DW10 engine, 2004 vintage.
My cooling fan doesn’t come on when the engine temperature gets hot enough for it. The previous owner had the same problem and put in a by-pass switch in the cabin to manually switch on & off the fan wired direct. I bought the car in winter and thought nothing of it at the time, but now we have summer temps, the car definitely gets hot in traffic jams and the switch in the cabin worked but then it melted and stopped working altogether. I imagine it wasn’t capable of handling high amps.
I would like to fix the original problem instead of using the by-pass switch. Looking online I have found this cooling resistor relay:
https://www.ebay.co.uk/itm/Citroen-Berl ... Sw6CJbFTdE

I once had a Berlingo heater fan stop working & changed a similar looking part resistor to fix it; is it likely to be this or should I be looking at something else too?
I see that this fan resistor is sited in front of the radiator and requires the bumper to be removed to access it…

Thanks for any advice