[minulache]

Hi guys,
Looking for a bit of guidance, where to start. Today I drove the car and no problems, until I left it idle for a longer time and realised at some point the coolant started overflowing, it was boiling. At the same time, I realised the fan was barely working to cool the engine down. From the tester, I tested to see if the fan works properly at full RPM and it did with no problems, so I guess the problem might be coming from the wiring or maybe the relay?
If any of you had the same problem, I'm looking forward to your advice or maybe possible fixes for this. The coolant reservoir, thermostat, coolant pump and radiator have been changed previously, like 2-3 years ago so I kinda doubt the problem is from there but who knows.