my car is an optra, year 2005.
recently im having overheating issues with it.

i was told that the radiator fan is working on 2 speeds, low and high.
after it reaches a certain temp, the radiator fan should switch from low to high speed.
unfortunately, my radiator fan is not.

the bigger problem here is that i brought it already to a nearby casa.
they cant fix it because they can not find any error everytime they run the diagnostic test.
the sensor is reading the temperature correctly.

any advice folks? TIA