its the builtin issue in almost all every 660cc Japaneses car, i also faced it in my Mitsubishi EK wagon, and my friend's Japanese alto has a same problem, its not due to breaking it is mainly due to low RPM, since 660cc cars are under power cars therefore the compressor of these cars have been designed in such a way, which automatically turned off below certain RPM. during the time i have EK wagon i tried each n every thing but the problem remained unsolved, unless i had to sale it.