How can you get the old refrigerant out of a 89 Toyota pickup?

If the AC has not been retrofitted, it will have R12 refrigerant in it, which is illegal to release into the air. Most auto shops used to have a R12 recycling/recovery system, but most will not, because R12 is obsolete and VERY expensive. The shops will remove the freon from the low & high side schrader valves (like tire inflation valves). Once the freon is evacuated, they pull the system down with a vacuum. This makes it easy to introduce the new freon, which is R-134a (self charging lines are widely available for $10 & about $9 a can for freon. each car will have the recommended amount of freon, usually on a sticker on the accumilator.