AC is for providing a regulated temperature, not just keeping the coach cool. In summers, people take AC to avoid the hot weather outside and in winter they take AC to avoid the extreme cold weather outside (Just look at people doing overnight travel in SL coaches in winter!! ). AC coach patronage is not seasonal and they enjoy good patronage throughout the year. Besides 3A demand has increased now with more people preferring the comfort as they are able to afford it more easily. But one thing is that most of these trains are not 24 coachers. Instead of replacing the SL, 3A could have been added to the consist.