Refrigerant Evacuation for Air Conditioners

Evacuation of refrigerant in air conditioner has three benefits. These are,

  • preparing the air conditioning system for total repair, e.g. compressor replacement,

  • making sure that refrigerant that is originally contained within the system, is not released into the atmosphere

  • charging a non azeotrope (400 series, except for R-410) refrigerant

This type of air conditioning maintenance is performed by an external compressor, attached to the system through the service valve.

How to perform refrigerant evacuation:

How evacuating refrigerant differs from pump down?

Good question. I wish I know the answer.

Air conditioning system pump down,

  • in a system without a receiver, will only permit maintenance from the condenser’s outlet, to suction of the compressor

  • in a system with a receiver, will permit maintenance on all air conditioning part, except for the receiver

On the other hand, evacuating refrigerant permits maintenance on all part of the system. The process utilises an external fluid mover, and an external refrigerant cylinder.

The steps for evacuating refrigerant are,

  1. shut down the air conditioning unit,

  2. attaching pressure gauge set tightly to the service valves.

    Plain gauge set to be connected to the liquid line service valve, and compound gauge to be connected to the vapour line service valve.

    NOTE: Make sure that the regulators on the gauge set are in closed position

  3. connect a vacuum pump to the centre manifold of the gauge set.

    It is preferable that the vacuum set comes together with a dryer, so that moisture can be removed from the evacuated refrigerant.

    A cylinder to store the refrigerant is a MUST, and it should pass the regulations by EPA (Environmental Protection Agency)

  4. open the regulator of the compound gauge side,

  5. operate the vacuum pump to draw the refrigerant out of the air conditioning system.

  6. wait until the pressure within the system reaches 0.

    Stop the pump and close the regulator

  7. observe for pressure rise.

    • if the pressure rises rapidly until atmospheric pressure, then the connections might be loose. Tighten the connections and redo steps (4) to (6), and observe.

    • if the pressure rises rapidly at this point, then there is a leak within the system.

      Leak detection, repair and recharge is inevitable.

    • if the pressure rises slowly, then there is either moisture or remaining refrigerant in the system.

      Open the compound gauge regulator and resume evacuating

  8. hold the pressure at 0 for a few hours or half a day (depending on the size of the ac system),

  9. isolate the gauge set’s regulator and remove the gauge set,

  10. do necessary repairs or parts replacement after the evacuation,

  11. perform leak test after the repair or replacement,

  12. evacuate refrigerant once more after the leak test.

    Start from steps (2) to (9),

  13. recharge the refrigerant using the previous refrigerant, or a new one

Air conditioning evacuation setup. Air conditioning evacuation is also known as refrigerant evacuation
Courtesy for condenser picture: Bryant Air Conditioners

Evacuation. The governing law:

Recovered refrigerant shall never be sold or used for other air conditioners, unless if it is re-processed by EPA approved facilities.

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