5.3 liter h3a how much freon?

 

based on available information,,a wild guess is; enuf to get the compressor to stay kicked in and you get cold air.
just add some

 

Yeah, but too much and it won't cool efficiently and too little may freeze the evaporator. You can look at the high/low pressures. They will be dependant on outside air temp. Your best bet is to take it in and spend ~$100 and have the line evacuated, have a vacuum held on it to check for leaks, then have the freon added back in measure in weight instead of pressures. Much easier that way.