Pumping Down an AC or Refrigeration System
To remove refrigerant from an air conditioning system, a technician has to perform a recovery and pump down procedure. This document will ensure that you have a basic understanding of the important concepts and basic steps involved with recovery and pump down.
Pumping down an AC or Refrigeration system is both important and a legal requirement. With recent refrigerant prices increasing, recovering the refrigerant to reuse is just common sense. It is illegal to release into the environment and can result in fines in New Zealand.
The best way to handle the refrigerant is by utilising a recovery unit or recovery machine that is connected to a storage cylinder. It’s important that all technicians know how to pump down an air conditioning or refrigeration system. Some air conditioning systems have built in receiver (storage) for convenient pumping down, however a similar process still must be followed.
You will need specialised refrigeration tools for completing the pump down correctly, including a recovery machine, manifold gauges, and a torque wrench set.
There are many different steps in the recovery and pump down operation depending on the unit and set up. A technician should have previous experience or specialised training before attempting a recovery and pump down process by themselves. This document will ensure that you have a basic understanding of the important concepts and items associated with recovery and pump down.
Outline of steps for pumping down an air conditioning and refrigeration unit:
- Switch off the air conditioning unit
- Connect the manifold to the low pressure service valve
- Using your refrigeration service tools, release the nut on the service valve, to a mid-way position between fully opened and fully closed. You should see that that the pressure gauge reading will increase on the manifold gauge.
- Operate the air conditioning unit for 3 to 5 minutes,
- Isolate the liquid line by closing off the liquid line service valve. You should start to see the reducing pressure reading on the manifold gauge.
- Once the pressure reads zero, isolate the vapour line service valve by closing the service valve off,
- Evacuate the system after the repair and maintenance work by using a high performance Javac Vacuum Pump to 25 microns or less. This step is very important otherwise your system will not operate correctly. This is to remove the moisture and oxygen.
- Next open the service valves and wait for 5 minutes for the refrigerant to disperse.
- You may now turn of the air conditioning or refrigeration unit.
- It is suggested that you use a Hand Held Leak Detector to check for any leaks around any new joins or changes to the refrigerant piping.
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