Hello PW! I want to add update to this thread. I had weak compressor in my santro as i mentioned before.
Today i went to Coolsun car A/C and they told that they will fit Toyota Duet compressor in it. They said original one is costly and made in china.
So, I installed the Duet compressor. It was bolt on fitting with alteration in piping only. After installation two things i noticed very good in car.
Absolutely no or very minimal load on engine. Car runs on A/C as running with A/C off.
Cooling is awesome and no noise of on/off of compressor.
I will update how the A/C works in next coming days as it is first day.