To reclaim refrigerant from an air conditioning system using a recovery unit, attach a set of HVAC gauges to the components, connecting the red hose to the high side of the system, the blue hose to the low side, and the yellow to the suction line of the recovery machine marked "in." Connect a hose from the "out" port of the recovery machine to a recovery tank, purge air from the lines, and then turn on the recovery unit.
To purge air from the lines prior to recovery, open all the valves from the unit to the tank. Unscrew the hose slightly at the tank until air escapes. Wait one second, and then reconnect the hose to the tank.
After turning on the recovery machine, the pressure on the gauges drops as the refrigerant enters the recovery tank. Place the recovery on a scale to measure the amount of refrigerant removed from the system. Only fill a tank to 80 percent of its capacity. When the recovery machine reaches zero psi, shut it off, and close all the valves, especially those on the recovery tank..
U.S. regulations prohibit anyone who is not certified by the Environmental Protection Agency to buy or work with any type of refrigerant.