In response to the questions about how many cans of Freon. In the past you would just view the sight glass and watch the bubbles. When the bubbles went away, it had a sufficient charge of Freon. If you suspected the Freon was low, you just looked at the sight glass.

Has it changed now for the older cars with Freon? My 81SD has a sight glass and still runs Freon and feels like a meat locker.