Air Conditioning System Pump Down

There will come a time, when you have to pump down your air conditioning unit for repairs on the air conditioner.

This air conditioning maintenance activity has a purpose, and that purpose is, to…

accumulate refrigerant in the condenser, or receiver of the air conditioner.

System pump down will also save the time required to contain all refrigerant within the system, while repair works are being carried out.

Releasing the gas into the atmosphere into the atmosphere is out of question.

Method for air conditioner system pump down:

The beauty of this method is that, you wouldn’t need additional pump to perform the pump down action. Compressor of your air conditioner is sufficient to do the job.


  1. switch off the air conditioning unit, then,

  2. attach the compound pressure gauge to the vapour line service valve

  3. turn the knob on the service valve, to position it in between fully opened, and fully closed.

    You will notice that the pressure gauge reading will increase

  4. next, operate the air conditioning unit for 3 to 5 minutes,

  5. isolate the liquid line by closing the liquid line service valve.

    You will start to notice the reducing pressure reading on the compound gauge

  6. isolate the vapour line service valve by closing it, once the pressure reading 0.

    Refrigerant within the low pressure side should be very minimal at this point. So, you can do necessary repair work, or parts replacement work on the unit.

    Please note that you can do major maintenance on all air conditioner parts, except for the condenser and compressor,

    IF you don’t have use a receiver.

    Some air conditioning units have built-in receiver, and therefore, maintenance on ALL parts can be carried out, except for the receiver.

    UNLESS, if you use a separate cylinder as a receiver, then you can do maintenance on all air conditioning parts. But then, it won’t be under this topic, it will be under evacuation instead.

  7. evacuate the system after the repair and replacement works.

    This step is super vital to remove the moisture

  8. open the service valves, and wait for 3-5 minutes,

  9. you may operate the air conditioning unit now

Additional steps worth considering after a pump down, are superheat and subcooling check.

Never forget one thing though. Safety first. Wear gloves, and evacuate the area if there is a major leak.

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