yes
check the condenser name plate. it will tell you the type of refrigerant.
yes, older units could take between 9 and 15 lbs of freon most take about 12
overcharging a central air unit system with refrigerant(freon) will cause the head pressure to be?
low on freon
If you are talking about the old R12 freon, you can't legally buy it. The only people who are allowed to buy it are certified air conditioning repair technicians. The government regulates R12 because it is highly toxic to the environment.
I just had 2 pounds of Freon added to my central A/C and was charged $30 a pound.
Actually no technical skills needed to check the Freon level. Home central air conditioners have a Freon scale on it. One just need to read the scale and determine whether the level of Freon is sufficient.
brazing
actually this is a pet project of mine to produce a Freon-less A/C unit
Learn how to spell
Yes.