I 'm charging the system in a Ideal 55 and the tag Say's .42 lb of R12  . Am I correct in putting in 6.7 oz ? or is it 5.0 oz ? This machine has three cooling tubes on each side and one across the bottom, It has a long tube that is soldered to the last cooling tube to the compressor for the thermostat. When I charged this it runs for about five min and then shuts down the thermostat. My guess is that the frost made it back to the long tube and shut it down. Is my math wrong on the charge amount and the system is over charged and causing the problem or what. Thanks