Turtles, you use a recovery/charging system. Connects to the system and evacuates the freon into a tank. The system also removes the oil from the system. It will tell you how much freon and oil was removed. When the work is done on the a/c unit, you use the same system to recharge it. By law you are not allowed to vent freon to the atmosphere.
97 Sahara, 74 Renegade, 72 CJ5, 55 Willy's (the Beast) Boss 302, 6:34 gearing, Bose 901 speakers.
God I miss that Jeep. Forgot the kinda Jeep, 80 SX4.