For the leak test, intubate the nitrogen gas and apply the pressure as described by the manufacturer.
The gas, liquid side and the balance valves must be completely closed. Note that there is a possibility that the nitrogen gas will mix with the outdoor unit cycle. Therefore, tighten the valves again (gas side, liquid side and balance) before applying any pressure.
Never use oxygen, flammable or toxic gas for leak testing.
Gradually apply pressure, according to the steps indicated on the gas, liquid and balance side of each refrigerant system individually.
When pressure is detected in the system, check for leakage at the connection points. Check the leak with your ears, feeling, with foam, etc. and re-weld or tighten the flange if a leak is detected.
