bro...first of all im not an expert...
in Pakistan, santro launched without RPM guage, wat abt ur santro? does it have RPM? or r u using aftermkt one? or any scanner to accuratly set RPM?
if its a air bypass screw on the throttle body, then u can increase idle rpm by opening it and reduce by closing it.
first u must ensure that all other settings are according to factory spec, then moniter rpm on a warmed up engine, if different from factory specifications both with n without ac, u can adjust by opening or closing that screw...
then disconnect battery for 10 15 mins reconnect n check again