Pete, When we vacuumed the system, we let it sit overnight to check for leaks. Don't know if you did that, but it's not a bad idea.If all else fails, read the instructions :idea::laugh:. According to Vintage Air, it takes just over two cans (28.8 oz) to fill the system. I've got a little less than two cans in right now.
Tools used to fill the system:
Harbor Freight vacuum pump: Vacuum Pump - AC Vacuum Pump w/ R134A & R12 Connectors
Manifold Gauge Set: AC Gauges - Save on this AC Manifold Gauge Set