How much R-134a should be placed in an ac for a 1988 mercury grand marquis that was converted from R-12?

For a 1988 Mercury Grand Marquis converted from R-12 to R-134a, the typical charge amount is approximately 80% of the original R-12 capacity. Since the original R-12 capacity is around 3.0 to 3.5 pounds, you should aim to add about 2.4 to 2.8 pounds of R-134a. It's essential to check the specific system requirements and any updates from the manufacturer for the most accurate charge. Always ensure the system is properly evacuated and leak-tested before recharging.