i think there is a soft foam substance like seal all around condenser. So when he removed it and washed it with pressure water from service station that layer got removed. And i am sure he never put any sealing substance back on condenser lining.
Either that or he messes up with firewall while taking out condenser and its pipes and doesn't put it back properly
I got it checked from aqash and abu-bakar's big brother mohal car ac i-10 but both were not bothered by it much. One sprayed some wd40 on fresh/recirculation vane and the other said motor is weak so door is not closing fully but it was fully closing when i saw and felt with hand my self.
3s seems the only option. On a side note, i have felt that 3s people do not take old cars seriously now. I have always been going to them for the past 10 years for all sort of work but now their quality of work has reduced. Their high cost of labor is not justified any more.