When a household refrigerator compressor does not run it is recommended that low and high side access valves be installed when recovering refrigerant from the system because?

The last thing you want to do is tap into a closed system, this is the beginning of the end in most cases. If a unit is damaged, the refrigerant will be gone anyways. A refrigerator holds 4 oz. to 5 oz. refrigerant, it takes a tiny leak to deplete it entirely.

Should you need to pump a system down then you can install a tap temporarily and sil floss in a proper suction line access, the high side is optional.