After leak testing with nitrogen and R22, what should be the next step?

The most appropriate next step after conducting leak testing with nitrogen and R22 is to vacuum the system. During leak testing, nitrogen is utilized to pressurize the system and check for leaks, and R22 is likely the refrigerant being used in the system.

Vacuuming the system is crucial because it removes any moisture and non-condensables from the refrigerant lines before the system is charged with refrigerant. Moisture can lead to acid formation in the refrigerant, which can cause serious damage to the system components. By establishing a vacuum, you ensure that the system is clean and ready for refrigerant, which promotes optimal performance and longevity of the HVAC or refrigeration system.

Sealing the system and conducting a pressure test is a valid maintenance step but typically follows vacuuming to ensure there are no leaks under operating conditions. Venting refrigerant and nitrogen to the open air is unsafe and not environmentally responsible, while charging the system immediately without proper vacuuming could lead to contamination and operational issues.