Get Sanden. if ur budget allows u Denso is the best.
and yes A/c does work in a mehran wid CNG, (no wonder Paksuzuki is offering it as Factory Fitted) so obviusly it works.
800cc People around Pakistan use Ravi's and Bolan's for loading purposes. so if ur car is mechanicaly fit engine is fit A.c shud work properly. Altho after that u wont be getting a top performance out of it.
But jitny garmi hogae hai i guess one can afford driving at 60 km/h with a.c rather then driving at 100 km.h all the time.