When using a passive system-dependent recovery process, when should both the high and low sides be accessed for refrigerant recovery?

In a passive system-dependent recovery process, accessing both the high and low sides is essential when the compressor is not running to ensure efficient refrigerant recovery. This approach allows for the collection of refrigerant from both the low-pressure side and the high-pressure side of the system.

When the compressor is off, the refrigerant pressure can equalize throughout the system, enabling more complete recovery as it allows refrigerant from the low-pressure side to flow into the recovery device. If the compressor is running, accessing both sides may not yield effective recovery, as the compressor might create suction that draws in refrigerant from only one side. When the system is leaking, it would be impractical and inefficient to attempt recovery from both sides, as the loss of refrigerant can complicate the process and result in uncertainty about how much refrigerant is still in the system.

Thus, accessing both high and low sides when the compressor does not run maximizes the chances to recover the remaining refrigerant effectively and safely.