An R-12 to R-134a conversion procedure requires that Technician A says to leak-test the system and conduct a performance test prior to removing the R-12. Technician B says to leak-test the system and conduct a performance test after charging the system with R-134a. Who is correct?

The correct answer is that both technicians are correct in their procedures when it comes to converting an R-12 system to R-134a.

Technician A's procedure of conducting a leak test and performance test prior to removing the R-12 is important because it ensures that any existing leaks are identified and addressed before the refrigerant is removed. This helps in maintaining the integrity of the system and prevents any environmental release of refrigerants, which is regulated due to their ozone-depleting potential.

Technician B's recommendation to conduct a leak test and performance test after charging the system with R-134a is also valid. Once the new refrigerant is in place, it is crucial to verify that the system is operating correctly and that there are no leaks with the new refrigerant type. This helps to ensure that the system is functioning efficiently in its new configuration and that the conversion was successful.

Both steps are critical in ensuring the integrity and efficiency of the air conditioning system throughout the transition from R-12 to R-134a. Thus, it is accurate to say that both technicians' approaches contribute to a proper and safe conversion process.