Lumina 2010 LTZ Overheating Problem

My Lumina 2010 LTZ (LY7 v6 Engine) starts overheating while idling at red light or at low speed in traffic jams. Been having this issue for 6 months and everytime I get it fixed and it keeps coming back.
First time it happened, I went to a mechanic and same time the battery died.
Replacing the battery fixed the heating problem, [as explained by mechanic probably the second fan runs at low speed using the battery (and it wasn't since the battery was about to die) and when the engine heats up it starts on high speed with engine power. Didn't see the overheating issue for next two months after which he suggested to drain the radiator and refill with a new coolant. Fixed the issue for 3 months.
Now the overheating start again and this time, its summer here ( earlier it was winter) . The issues seems more alarming this time as earlier everytime it used to overheat, I used to switch off the AC and just keep the blower(fan) ON and somehow it would keep the temperature controlled while I'm at signal or traffic and gave me time to reach a parking where I could wait to get it cooled off. This time even the blower seemed to affecting it and even after I switched it off, it almost reached 90% ( previously it would only be at about 75% and stay constant )
When I look under the hood, the engine seems to be cold, and the fans are still running. I turn off the car, wait 5 minutes and turn it on again, and its back to 50% and I drive back home.

I am suspecting either the fans are working intermittently  or is this a sensor issue ? Any guidance please.