Leak Check and Evacuation) Evacuation Procedure

 

1. Preparatory Steps Before Evacuation

• Recover Refrigerant:
  • Ensure all refrigerant is recovered from the system.
• Release Nitrogen:
  • If you performed a pressure test, release the nitrogen to ensure the system is at 0 PSIG.
  • Warning: Failing to release nitrogen can blow oil out of the vacuum pump, causing a mess and potential damage.

2. Initial Vacuum Test on Gauge Set

• Purpose: Verifies that hoses, micron gauge, and vacuum pump are functioning properly.
• Steps:
  • Pull a vacuum on the gauge set to 500 microns.
  • Check for leaks, ensure micron gauge accuracy, and confirm the pump's performance.

3. Address Common Issues

• Micron Gauge:
  • If not working properly, clean the thermistor with isopropyl alcohol.
• Vacuum Pump:
  • If oil is dirty or contains moisture, change it to fresh oil to achieve a deep vacuum.

4. Evacuation Procedure: Step-by-Step

• Initial Setup:

  • Connect the high and low side hoses to the system.
  • Attach the charging hose to the vacuum pump from the middle port of the manifold.

• Pull Initial Vacuum on Gauge Set:

  • Close manifold and service valves.
  • Start the vacuum pump and pull down the vacuum on the manifold and hoses to 500 microns.
  • Ensure there are no leaks and everything is functioning properly.

• Evacuate the System:

  • Open suction service valve and discharge service valve.
  • Start the vacuum pump and pull a deep vacuum.
  • Continuously monitor the micron gauge.

• Check for Holding Vacuum:

  • Once 500 microns is reached, valve off the vacuum pump.
  • Observe the micron gauge for 5 minutes to ensure it holds the vacuum.
  • Some increase in micron level is normal; ensure it stabilizes below 1000 microns.

5. Practical Considerations During Evacuation

• Patience and Persistence:

  • The process can take time, especially if moisture is present.
  • Be prepared to continue vacuuming and waiting until a stable vacuum is achieved.

• Moisture Removal:

  • If micron levels rise to 1500-50,000 and stabilize, it indicates moisture boiling off.
  • Continue vacuuming until moisture is removed and a deep vacuum is held.

6. Final Steps: Preparing for Charging

• Confirm System Integrity:

  • Ensure the system holds a deep vacuum below 1000 microns.
  • Validate there are no leaks and the system is moisture-free.

• Ready for Charging:

  • Once the system holds the vacuum, it is ready for refrigerant charging.