Question 101Refrigeration & AC - Assistant Engineer

You are correct, the answer A) suction service valve as a vapor is the correct answer. To add small amounts of refrigerant to the low side of an air conditioning system, the refrigerant should be introduced through the suction service valve in a vapor state. This allows the refrigerant to properly mix with the low-pressure refrigerant in the suction line and get drawn into the compressor. Adding liquid refrigerant directly to the low side could damage the compressor. The other options, such as using the discharge service valve or adding liquid refrigerant, are incorrect as they would not properly integrate the new refrigerant into the system.