At Godrej, we do not permit such direct replacement of refrigerant; especially when the original compressor/refrigeration system was designed for R-12 and a technician would want to charge R-134a into it. Instead, refer to Godrej Training Manual TM-1005 wherein retrofitting is explained. The process is expensive and calls for extra care.
We do not permit it as it needs a change of lubricating oil from mineral oil to Poly-ol Ester oil. The residuals of mineral oil may contaminate the system, which at a later date can damage the compressor. The capillary tube and even the condenser may need a change. Over & above cleanliness is of utmost importance while working with POE oils & R-134a refrigerant.