Hi pradoartz,
I see you are from India. Care to tell us which part and put it next to 'Location' on your user page so that it shows in the window at the left of your posts.
I have some sympathy with you about your fan failing. I had the same thing on my automobile when 200 miles away from home. Cost me a small fortune to have the automobile towed back home. The problem turned out to be a faulty fan motor and a sticky relay.
I suspect that there will be a relay from the ECU that turns the fan motor on and off.
Can you check:
(1) The relay for correct operation
(2) The wiring for corrosion breaks
(3) The connectors for tight fit and corrosion.
Failing that, a simple circuit will bypass the ECU as the other members have already stated.
spec
By the way nice informative opening post- wish we had more like that.