Air and moisture in the refrigerant will cause problems in the air conditioning system. Therefore, before charging the refrigerant, be sure to evacuate air and moisture thoroughly from the system.
Connect the gauge manifold:
- High-pressure valve (HI) - Discharge-side.
- Low-pressure valve (LOW) - Suction-side.
- Discharge and recover the refrigerant.
- Connect the center hose of the gauge manifold set to the vacuum pump inlet.
- Operate the vacuum pump, open shutoff valve and then open both hand valves.
- When the low-pressure gauge indicates approximately 750 mmHg (30 inHg), continue the evacuation for 5 minutes or more.
- Close both hand valves and stop the vacuum pump.
Check to ensure that the pressure does not change after 10 minutes or more:
- If the pressure changes, check the system for leaks.
- If leaks occur, retighten the refrigerant line connections and repeat the evacuation steps.
- If no leaks are found, again operate the vacuum pump for 20 minutes or more. After confirming that the gauge manifold pressure is at 750 mmHg (30 inHg), close both hand valves.
Close positive shutoff valve. Stop the vacuum pump and disconnect the center hose from the vacuum pump.