I didnt judge - I provided my working experience - so hold your horses..
the sentence of "800cc car mein ac nahi chalta" - was coined by used car salesmen and morons with tools selling "thandi AC service"
It was done to offload responsibility from themselves, The equipment (A/C) is capable of cooling down the cabin provided that the manifacturer recommendation are followed.
you can give those morons with tools any car - and they will automatically say.
kompressur khatam hai, fel system hai, komnee faalt hai iss me, ye sanden lagalein, poori service ke saath 50K ka kharcha hoga, 3 season nikaal lega.
yes, they will say 3 seasons, while any random car in the world (outside of Pakistan) has working A/C for decades without such morons touching it.